Periodic+Table

2-3) =**[|Periodic Table]**= __**Period**:__ Are the horizontal lines that tells you the energy level that an element has __** Group: **__ Are the vertical lines that tell you what group an element is in __ ** Molar Mass **: __ The mass of a molecule in grams pr mole, the sum of the componet atomic masses; molecular weight.[|Periodic Table] __**Electronegativity** : __ Containing negative electricity; tending to migrate to the positive pole in electrolysis. assuming negative potential when in contact with a dissimilar substance. [|nonmetallic.] __**Atomic Radius:**__ T﻿﻿he radius of an atom; the distance from the atomic nucleus to the outermost stable electron orbital in a atom at equilibrium; also, one-half the distance between nuclei of atoms of the same element, when the atoms are bound by a single covalent bond or are in a metallic crystal __**Diatomic Molecule**:__ Molecule composed of two atoms joined together, which may be atoms of the same (such as oxygen, O2) or of different elements (such as hydrogen fluoride, HF). __**Avogadro's Number**:__ the number 6.0021367X10^23, which is the number of representative particles in a mole, and can be rounded to three significants digits:6.02X10^23.(CHEMISTRY MATTER AND CHANGE) __** Periodic Law **__ __:__in chemistry, law stating that many of the physical and chemical properties of the elements tend to recur in a systematic manner with increasing atomic number. __**Ionization Energy**:__The term ionization energy (**EI**) of an [|atom] or [|molecule] is the minimum [|energy] required to remove (to infinity) an electron from the [|atom] or [|molecule] isolated in free space and in its ground electronic state. This quantity was formerly called **ionization potential**, and was at one stage measured in volts. The name "ionization energy" is now strongly preferred. In atomic physics the ionization energy is measured using the unit [|"electronvolt" (eV)]. __**Shielding Effect**:__ Electrons in filled sets of S,P orbitals between the nucleus and outer shell electrons shield the outer shell electrons somewhat from the effect of protons in the nucleus; also called screening effect. [|Perodic Table!!]
 * __ Mole: __** Is a unit of measurement for the amount of substance or chemical amount

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= Diatomic Elements =

=== Diatomic elements are considered “pure” in the sense that they can bond with another molecule of the same element; this is called covalent bonding. In covalent bonds both atoms gain electrons by sharing electrons with each other. This forces them to bond. The diatomic elements are Hydrogen, Nitrogen, Oxygen, Bromine, Fluorine, Chlorine, and Iodine. ===

For Imformation Over "how to calculate the molar mass of a given compound" go to: []media type="youtube" key="LDHg7Vgzses?fs=1" height="385" width="640"

= Explain why elements in a group have similar properties. = []
 * Elements** in the same group have similar properties because the elements outer orbital contains the same amount of valence electrons and the amount of valence electrons in the outer orbital determines the elements reactivity.

__** Diatomic Molecules **__
Have you wondered why when oxygen is listed, it is written as O2? Because **oxygen is a diatomic molecule**. //Diatomic molecules are element that are too reactive to be found as a single atom in nature//. Because of that, they form a compund to be more stable. The **diatomic molecules are: Nitrogen (N), fluorine (F), oxygen (O), hydrogen (H), Chlorine (Cl), bromine (Br), and iodine (I).**

So the **diatomic molecules are:** H2, O2, N2, F2, cl2, Br2, and I2!!

=__**Metals, metalloids, and nonmetals**__= How can you tell if an atom is a metal, a nonmetal, or a metalloid? The easy way to find out is that all the elements located to the right of the steps are nonm﻿etals, and to the left are metals. However, if you want to know where metalloids are, they're along the steps. This means that some of the elements to the left of to the right of the steps are metalloids. The elements that are metalloids are: Boron (B), silicon (Si), germanium (Ge), arsenic (As), antimony (Sb), tellurium (Te), and astatine (At). If you want to know what I mean by "steps," there is a bolded zigzag line towards the right of the periodic table.

=__**Properties of Groups:**__= The properties of the [|elements] exhibit trends. These trends can be predicted using the [|periodic table] and can be explained and understood by analyzing the [|electron configurations] of the elements. Elements tend to gain or lose valence electrons to achieve stable octet formation. Stable octets are seen in the inert gases, or noble gases, of Group VIII of the periodic table. In addition to this activity, there are two other important trends. First, electrons are added one at a time moving from left to right across a period. As this happens, the electrons of the outermost shell experience increasingly strong nuclear attraction, so the electrons become closer to the nucleus and more tightly bound to it. Second, moving down a column in the periodic table, the outermost electrons become less tightly bound to the nucleus. This happens because the number of filled principal energy levels (which shield the outermost electrons from attraction to the nucleus) increases downward within each group. These trends explain the periodicity observed in the elemental properties of atomic radius, ionization energy, electron affinity, and [|electronegativity]. [|Periodic Table]

=__**Groups**__ (columns in the periodic table) are composed of elements that have the same valence electrons, which means they have the same chemical properties. This means they can replace each other in a compound. The main groups are **Alkali Metals, Alkaline Earth Metals, Transition Metals, Metalloids, Halogens and Noble Gases**.=

The //**Metalloid's**// are located on the **steps** but only seven of the elements located on the steps are metalloid's and they have properties of both non-metals and metals. They are:**Boron (B), Silicon (Si), Germanium (Ge), Arsenic (As), Antimony (Sb), Tellurium (Te), and Astatine (At).** The //**Alkali Metals**// are located in **group 1** They are called alkali metals because group one metals react with water to form alkaline solutions. The //**Alkaline Earth Metals**// are located in group 2 (except for Beryllium Oxide) and are shiny solids that are harder than alkali metals. They are also called "oxides." The //**Transition Metals**// are located from **groups 3-12** in the periodic table and tend to be colored. //**Noble Gases**// are the elements in **group18** that have **8 valence electrons** so they are less likely to form compounds.Have a full outer most shell. They are found as mono-atomic gases. Last but not least, //**Halogens**// are located under **group 17** (also called " salt formers ") contain the most reactive nonmetals.

__**Where Each Type of Element is Located**__ __//Alkali metals//__ are in group 1; Hydrogen (H), Lithium(Li),Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs) and Francium (Fr). __Alkaline earth metals__ are in group 2; Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), and Radium (Ra). __//Transition metals//__ are groups 3-12. Scandium (Sc),Titanium (Ti), Vanadium (V), Chromium (Cr), Manganese (Mn), Iron (Fe), Cobalt (Co), Nickel (Ni), Copper (Cu), Zinc (Zn), Yittrium (Y), Zirconium (Zr), Niobium (Nb), Molybdeum (Mo), Technetium (Tc), Ruthenium (Ru), Rhodium (Rh), Palladium (Pd), Silver (Ag), Cadmium (Cd). There are more transition metals but those are some. __//Halogens//__ are in group 17; Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I), and Astatine (At). __//Noble gases//__ are in group 18; Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rn). and the __//metalloids//__ are located on the "steps (Boron(B), Silicon (S), Germanium (Ge), Arsenic (As), Antimony (Sb), Tellurium (Te), and Astatine (At))." ﻿--Periodic Table __ [] __
 * Source ** **s**- textbook and periodic table.



Nonmetals are located to the right of the stair case but it also includes Hydrogen (H).Metals are located to the left of the stair case but NOT including Hydrogen (H).Metalloid's are located on the stairs (touching) but Does NOT include Aluminium (Al) and Polonium (Po). [|] []

=ALKALI METALS TO THE LEFT= Let's start on the left side of the periodic table. When looking for families, the first one you will find is the **alkali metal** family of elements. They are also known as the alkaline metals. You should remember that there is a separate group called the **alkaline earth metals** in **Group Two**. They are a very different family even though they have a similar name. That far left column is ** Group One (Group I) .** When we talk about the groups of the periodic table, scientists use Roman numerals when they write them out.

=A FAMILY PORTRAIT= Who's in the family? Starting at the top we find hydrogen (H). But wait. That element is NOT in the family. When we told you about families, we said that they were groups of elements that react in similar ways. Hydrogen is a very special element of the periodic table and doesn't belong to any family. While hydrogen sits in Group I, it is NOT an alkali metal.

=FAMILY BONDING= Now that we've covered that exception, the members of the family include: **Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs) and Francium (Fr)**. As with all families, these elements share traits. They are very **reactive**. Why? They all have one electron in their outer shell. That's one electron away from being happy (full shells). When you are that close to having a full shell, you want to bond with other elements and lose that electron. An increased desire to bond means you are more reactive. In fact, when you put some of these pure elements in water, they will cause huge explosions.

The **alkali metals are also metals**. That seems obvious from the name. Often, in chemistry, characteristics are assigned by the way elements look. You will find that the alkali group is shiny and light in weight. Their light weight and physical properties separate them from other metals. Alkali metals are not the type of metals you would use for coins or houses.

=HEADING TO GROUP TWO= So we just covered the alkali metals in Group I. You will find the **alkaline earth metals** right next door in **Group II**. This is the second most **reactive** family of elements in the periodic table. Did you know why they are called alkaline? When these compounds are mixed in solutions, they are likely to form solutions with a pH greater than 7. Those pH levels are defined as 'basic' or 'alkaline' solutions.

=A FAMILY PORTRAIT= Who's in the family? The members of the alkaline earth metals include: beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba) and radium (Ra). As with all families, these elements share traits. While not as reactive as the alkali metals, this family knows how to make bonds very easily. Each of them has two electrons in their outer shells. They are ready to give up those two electrons in **electrovalent bonds**. Sometimes you will see them with two halogen atoms (BeF2) and sometimes they might form a double bond (CaO). It's all about giving up those electrons to have a full outer shell.

As you get to the bottom of the list, you will find the radioactive radium (Ra). While radium is not found around your house anymore, it used to be used in glow-in-the-dark paints. The other elements are found in many items including fireworks, batteries, flashbulbs, and special alloys. The lighter alkaline earth metals such as magnesium and calcium are very important in animal and plant **physiology**. You all know that calcium helps build your bones. =TRANSITIONING= Lets start off by telling you that there are a lot of elements that are considered **transition metals**. Which metals are the transition metals?
 * 21 (Scandium)** through **29 (Copper)**
 * 39 (Yttrium)** through **47 (Silver)**
 * 57 (Lanthanum)** through **79 (Gold)**
 * 89 (Actinium) and all higher numbers.**

=WHAT MAKES THEM SO SPECIAL?= It all has to do with their shells/**orbitals**. In **CHEM4KIDS** we try to stick to the first 18 elements because they are easy to explain. Transition metals are good examples of advanced shell ideas. They have a lot of electrons and distribute them in different ways.

Transition metals are able to put more than eight **electrons** in the shell that is one in from the outermost shell. Think about **Argon (Ar),** it **has 18 electrons** set up **in a 2-8-8 order**. **Scandium** is only 3 spots away with **21 electrons**, but it **has a configuration of 2-8-9-2**. Wow! This is where it starts. This is the point in the periodic table where you can place more than 8 electrons in a shell.

The **transition metals are able to put up to 32 electrons in their second to last shel**l. Something like **Gold (Au) has an organization of 2-8-18-32-18-1**. Of course, there are still some rules. No shell can have more than 32 electrons. It's usually 18 or 32 for the maximum number of electrons.

=ONE MORE THING= Most elements can only use electrons from their outer orbital to bond with other elements. __Transition metals can use the two outermost shells/orbitals to bond with other elements__. It's a chemical trait that allows them to bond with many elements in a variety of shapes. Why can they do that?

As you learn more, you will discover that most transition elements actually have two shells that are not happy. Whenever you have a shell that is not happy, its electrons can bond with other elements. Example: Molybdenum (Mo) with 42 electrons. The configuration is 2-8-18-13-1. The shells with 13 and 1 are not happy. Those two orbitals can use the electrons to bond with other atoms. =HALOGENS ON THE RIGHT= In the second column from the right side of the periodic table, you will find **Group Seventeen (Group XVII)**. This column is the home of the **Halogen** family of elements. Who is in this family? The elements included are **Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I), and Astatine (At).**

=WHAT MAKES THEM SIMILAR?= When you look at our descriptions of the elements fluorine (F) and chlorine (Cl) you will see that they both have seven electrons in their outer shell. That seven-electron idea applies to all of the halogens. They are all just one electron shy of having full shells. Because they are so close to being happy, they have the trait of combining with many different elements. You will often find them bonding with metals and elements from Group One of the periodic table.

We've just told you how **reactive** they are. Not all halogens react with the same intensity. Fluorine is actually the most reactive and combines all of the time. As you move down the column, reactivity decreases. As you learn more about the table, you will find this pattern true for other families.

=THEN WHAT IS A HALIDE?= The elements we are talking about in this section are called halogens. When a halogen combines with another element, the resulting compound is called a **halide**. One of the best examples of a halide is sodium chloride (NaCl). Don't think that the halogens always make ionic compounds. Many halides of the world are made with covalent compounds. =THE NOBLE INERT GASES= We love the inert gases. Some scientists used to call them the **noble gases**. These gases are another family of elements, and all of them are located in the far right column of the periodic table. For all of you budding chemists, the far right is also known as Group Zero (Group 0) or Group Eighteen (Group XVIII). This family has the happiest elements of all.

=WHY ARE THEY HAPPY?= Using the **Bohr** description of electron shells, happy atoms have full shells. All of the inert gases have full outer shells with eight electrons. Oh wait! That's not totally correct. At the top of the inert gases is little helium (He) with a shell that is full with two electrons. The fact that their outer shells are full means they are quite happy not reacting with other elements. In fact, they rarely combine with other elements. That non-reactivity is why they are called inert.

=WHO'S IN THE FAMILY?= All of the elements in Group Zero are **Inert Gases**. The list includes **Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rn).** Don't think that because these elements don't like to react, we don't use them. You will find inert gases all over our world. Neon is used in advertising signs. Argon is used in light bulbs. //Helium is used to cool things and in balloons//. //Xenon is used in headlights for new cars.// When you move down the periodic table, as the atomic numbers increase, the elements become rarer. They are not just rare in nature but rare as useful elements, too.

=BUT WAIT, THEY DO BOND!= Some do. As of about 40 years ago, scientists have been able to make some compounds with inert gases. Some have been used in compounds to make explosives and other just form compounds in a lab. The thing to remember is that they were forced. When going about their natural lives, you will never (never say never because there may be an exception) find the inert gases bonded with other elements.

They are [|semiconductors]. They conduct electricity, but not as well as metals. This property, particularly found in silicon and germanium, is responsible for the remarkable progress in the field of solid-state electronics. Transistors in electronics today are made from semiconductors. They have reduced the size of electronic components to an almost microscopic level--basically a microcircuit printed on a tiny silicon chip.
 * The properties of metalloids are between metals and nonmetals**. Generally, metalloids behave as nonmetals, both chemically and physically. But their electrical conductivity resemble metals.


 * **Seven Diatomic Elements**

H2, O2, N2, F2, Br2, I2, Cl2
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 * You should know that the following elements exist as diatomic molecules. One acronym that is used is like a person’s name… HON F BrICl (With HON being the first name, F being the middle initial, and BrICl being the last name) ||
 * **Hydrogen H2** || [[image:http://www.dce.k12.wi.us/srhigh/teachers/bheeren/Image20.gif width="36" height="15" align="center"]] ||
 * **Oxygen O2** || [[image:http://www.dce.k12.wi.us/srhigh/teachers/bheeren/Image21.gif width="75" height="42" align="center"]] ||
 * **Nitrogen N2** || [[image:http://www.dce.k12.wi.us/srhigh/teachers/bheeren/Image22.gif width="74" height="44" align="center"]] ||
 * **Fluorine F2** || [[image:http://www.dce.k12.wi.us/srhigh/teachers/bheeren/Image23.gif width="64" height="25" align="center"]] ||
 * **Chlorine Cl2** || [[image:http://www.dce.k12.wi.us/srhigh/teachers/bheeren/Image24.gif width="113" height="66" align="center"]] ||
 * **Bromine Br2** || [[image:http://www.dce.k12.wi.us/srhigh/teachers/bheeren/Image25.gif width="98" height="39" align="center"]] ||
 * **Iodine I2** || [[image:http://www.dce.k12.wi.us/srhigh/teachers/bheeren/Image26.gif width="124" height="49" align="center"]] ||
 * Note: The fact that these elements are diatomic only relates to these elements as isolated, neutral atoms. For instance, chlorine when in a compound can be NaCl or CaCl2 or AlCl3. The number of chlorine atoms depends on the charge of the atom with which the chlorine is paired. ||


 * Hydrogen (H2)
 * Nitrogen (N2)
 * Oxygen (O2)
 * Fluorine (F2)
 * Chlorine (Cl2)
 * Iodine (I2)
 * Bromine (Br2)

Read more: []

__** Noble Gases :**__ The noble gases are //located in Group VIII// of the periodic table. Helium and neon are examples of noble gases. These elements are used to make lighted signs, refrigerants, and lasers. The noble gases are not reactive. This is because they have little tendency to gain or lose electrons. __(Group 18)__ [|Periodic table] =**Ionization Energy**=
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 * __ Alkali Metals :__** The alkali metals //are located in Group IA (// first column //) of the periodic table//. Sodium and potassium are examples of these elements. Alkali metals form salts and many other compounds. These elements are less dense than other metals, form ions with a __+1 charge__, and have the largest atom sizes of elements in their periods. The alkali metals are highly reactive. __(__ Group 1 __)__
 * __ Alkaline Earth Metal ____s__:** The //alkaline earths are located in Group IIA (second column) of the periodic table//. Calcium and magnesium are examples of alkaline earths. These metals form many compounds. They have ions with a +2 charge. Their atoms are smaller than those of the alkali metals. __(Group 2)__
 * __ Transition Metals :__** The transition elements //are located in groups IB to VIIIB//. Iron and gold are examples of transition metals. These elements are very hard, with high melting points and boiling points. The transition metals are good electrical conductors and are very malleable. They form __positively charged ions.(3-12)__
 * __ Halogens :__** The halogens are //located in Group VIIA of the periodic table//. Examples of halogens are chlorine and iodine. You find these elements in bleaches, disinfectants, and salts. These nonmetals form ions with a -1 charge. The physical properties of the halogens vary. The halogens are highly reactive__.(Group 17)__
 * __We can see the elements in this Periodic Table!!__**
 * __**Metalloids:**__ They are the elements found along the stair-step line that distinguishes metals from non-metals. This line is drawn from between Boron and Aluminum to the border between Polonium and Astatine. Metalloids have properties of both metals and non-metals.This means that they can carry an electrical charge under special conditions. This property makes metalloids useful in computers and calculators. ||
 * Ionization energy ** is the energy needed to remove an electron from an atom to form an ion. The stronger the attraction between the nucleus and the electron is, the harder it will be to take away an electron. The harder it is to remove an electron, the more energy it requires.

[|Ionization Energy]

5.) Actually, the periodic table was a stunning predictor of properties of elements. When it was first formulated, many of the elements we know of today had not been discovered, and so it contained many blank spots. Interestingly enough, it turns out that the groupings predicted properties of elements in groups. For instance, you could be reasonably certain that if 12 new halogens are found in the future, they will all have similar properties to the halogens that are grouped together today.

How do we know this? How were the elements grouped by properties before we knew what those properties were? Simply put, the periodic table is organized like this:


 * Right to left: number of electrons in the outermost orbital


 * Top to bottom: atomic weight

This is oversimplified, but it works here. Electron configuration in the outer orbital is what determines an element's reactivity, the bulk of its chemical properties. Since there are 8 rows from left to right in the table, elements read from top to bottom all have the same number of electrons in their outer orbitals, so they all have similar properties.

What's important to remember is that much of the periodic table was organized in its modern state BEFORE we knew this. Pretty nifty.

__**Atomic Radius**__ This is how the atomic radius changes: //when it moves across the period (From left to right), it DECREASES//. You may wonder why. You probably might be thinking, "It //decreases//? How can this be?" I'll tell you why. //The reason is that as you move across the period, the protons will of course increase.// "__Since they have opposite charges, the force between the nucleus and the electrons (In energy levels) increases (Glencoe Scirnce Chemistry)." Because of that, the whole valence level is squished closer to the nucleus.__ __[|Atomic Radius]__

Also I'll talk about it vertical wise. If you go from top to bottom (Of a group), the atomic radius will also increase. How come? As you move down a group, a new energy level is added. So, period one has one valence level, period two has two valence levels, etc. Because of that, there is a greater distance between the valence level and the nucleus. _ __[]__

The **ionization potential** (or the **ionization energy**) is the minimum energy required to remove one electron from each atom in a mole of atoms in the gaseous state. The //first ionization energy// is the energy required to remove one, the //nth ionization energy// is the energy required to remove the atom's //n//th electron, after the (//n//−1) electrons before it have been removed. Trend-wise, ionization potentials tend to //**increase**// while one progresses **across** a period because the greater number of protons (higher nuclear charge) attract the orbiting electrons more strongly, thereby increasing the energy required to remove one of the electrons. As one progresses down a group on the periodic table, the ionization energy will likely //decrease//, since the valence electrons are farther away from the nucleus and experience a weaker attraction to the nucleus' positive charge. **There will be an increase of ionization energy from left to right of a given period and a decrease from top to bottom**. As a rule, it requires far less energy to remove an outer-shell electron than an inner-shell electron. As a result the ionization energies for a given element will increase steadily within a given shell, and when starting on the next shell down will show a drastic jump in ionization energy. Simply put, the lower the principal quantum number, the higher the ionization energy for the electrons within that shell. The exceptions are the elements in the boron and oxygen family which require slightly less energy than the general trend.

__The **Shielding Effect** is the effect caused when valence electrons (in the valence level) are "shielded" or guarded from the positive charge of the nucleus by the electrons in the inner energy level.__ __Across the periodic table the shielding effect stays constant because no new energy level are being added with in the same period. On the other hand, going down a group the shielding effect increases because as you move down you are increasing the number of energy levels. This increases the distance between the nucleus and the valence energy level which allows more inner energy levels to "guard" the nucleus.__

=__**Moles**__=

==== A mole is a unit of measurement used to measure the particles of an atom or a molecule. The actual number of a mole is 6.0221415×10²³ of whatever is being measured. It is based off of carbon-12 as that is the number of carbon atoms in 12 grams of carbon-12. The mole is a very impractical unit because the numbers are so big. ==== ==== The actual math involved in calculating moles is mass (grams) divided by relative mass (grams per mole). To calculate the mole of 20 grams of hydrogen one would calculate 20 grams divided by 1 gram to equal twenty. Hydrogen equals 20 moles. To find volume calculate concentration (mol/dm3) divided by volume (dm3). ==== ====[|Moles]==== How to calute Moles!! [|Moles Caculations]

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__**Why do elements in a group have similar property? **__ As you pass from left to right and from one line to the next line below it, you are increasing the atomic number of each element, one proton at a time. As the protons increase, so do the electrons and they fill up shells and start new shells. Chemical properties depend mainly on the number of electrons in the outermost shell (for transition state elements it doesn't work exactly by shells, since in the heavier elements it is possible for an electron in an inner shell to nonetheless be farther from the nucleus than some electrons in the outer shell, but that is an added complication). So, elements in the same group have the same number of outer, or valance electrons as they are known. Elements in the same group have similar properties because they have the same number of electrons in their outermost shell. Those with 3 or fewer electrons in that shell tend to be metals and those with 4 or more non metals. Metals lose their outer electron(s) when they react and non metals gain (or share) electrons when they react. The fewer electrons that need to be lost or gained the more reactive the element. So groups 1 and 7 are the most reactive. With metals the reactivity increases as you go down the group whereas with non metals the most reactive are towards the top of the group. The noble gases have complete outer electron shells and so are unreactive. __**Electronegativity **__

**Electronegativity** is the ability of an atom to attract electrons in a chemical bond. Electronegativity generally increases  when you go from left to right (across a period) . How come? When atoms are closer to having a full valence shell (8 valence electrons), the more able it is to attract electrons from other periods; except for group one because it only needs two to be full.



//When you go down a group, electronegativity decreases//. How come? Every new period means a new energy level to the atom. So, //the positive charge of the nucleus is further away from the valence level. This means that it is harder to attract new electrons// (Periodic trends foldable).

Calculating the molar mass of most atoms is very easy; it is just their atomic masses. There are a few exceptions to this such as diatomic elements.
The molar mass of NaCl is calculated like this: (1atom x the atomic mass of Na)+(1 atom x the atomic mass of Cl)=the molar mass of NaCl. So: (1 atom x 23 grams/mole)+(1 atom x 35.5 grams/mole)= 58.5 grams/mole The molar mass of NaCl is 58.5 grams/mole.

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__**CALCULATING THE MOLAR** **MASS OF CARBON (C):**__
The molar mass of elements is found by looking at the atomic mass of the element on the periodic table. For example, if you want to find the molar mass of carbon, you would find the atomic mass of carbon on the periodic table, and this is equal to the molar mass in grams per mole. So, in our example, carbon has a molar mass of 12.01 grams per mole.

**﻿**
The molar mass of an element is found by looking at the atomic mass of an element on the periodic table. For example, if you want to find the molar mass of hydrogen, you would find the atomic mass of hydrogen on the periodic table, and this equals to the molar mass in gram per mole. So, in my example hydrogen has a molar mass of 1.00 grams per mole.

__**CALCULATING THE MOLAR MASS OF POTASSIUM:**__
The molar mass of an element is found by looking at the atomic mass of an element of the periodic table. For example, if you want to find the molar mass of potassium, you would find the atomic mass of potassium on the periodic table, and this equals to the molar mass in grams per mole. So, in my example potassium has a molar mass of 39.09 grams per mole.

__**Ionization Energy**__
How does ionization energy change? It's the same as electronegativity. If you go from left to right, it increases. How come? Because the closer an atom is to having full valence level (eight electrons), then the harder it'll be to take away an electron, like Chlorine (Cl). When you go down a group, ionization energy decreases. Why, you may ask? The reason is that when you go down a group every element adds a new energy level. So, the valence electrons are farther away from the nucleus. This larger difference makes the attraction less, so it is easier to remove electrons from an atom. So, if there is less energy required, then it is easier (Periodic Trends Foldable).

__Shielding Effect __
When you go down a group, the shielding effect //increases//. You may be thinking, "Increases? How can this be?" I'll tell you why. When you go down a group, you're adding new energy levels. That increaes the distance between the valence electrons and the nucleus. This lets more inner energy levels to "protect" the nucleus. When you go across from left to right and vice versa, the shielding effect (Get ready for this) stays the same. You might think, "That's crazy!" But it's not. How? Simply, no new energy levels are being added within the same period (Periodic trends fordable). **﻿**

__﻿ __** __SEVEN DIATOMIC ELEMENTS__: **
 * Hydrogen, Nitrogen, Oxygen, Bromine, Iodine, Fluorine, and Chlorine**

Some mnemonic devices I found to remember are...
 * <span style="color: #ff0200; font-family: Verdana,Geneva,sans-serif;">I <span style="color: #000bff; font-family: Verdana,Geneva,sans-serif;">﻿ B **<span style="font-family: Verdana,Geneva,sans-serif;">ring **<span style="color: #800080; font-family: Verdana,Geneva,sans-serif;">C **<span style="font-family: Verdana,Geneva,sans-serif;">lay **<span style="color: #ffff00; font-family: Verdana,Geneva,sans-serif;">F **<span style="font-family: Verdana,Geneva,sans-serif;">﻿or **<span style="color: #ff00ff; font-family: Verdana,Geneva,sans-serif;">O **<span style="font-family: Verdana,Geneva,sans-serif;">ur **<span style="color: #008000; font-family: Verdana,Geneva,sans-serif;">N﻿﻿﻿ **<span style="font-family: Verdana,Geneva,sans-serif;">ew **<span style="color: #000000; font-family: Verdana,Geneva,sans-serif;">H **<span style="font-family: Verdana,Geneva,sans-serif;">﻿ome **

//AND//


 * **<span style="font-family: Verdana,Geneva,sans-serif;">BrINClHOF ** (like a last name)

=** Shielding Effect **=

The shielding effect is caused when the valance electrons (Ve-) are shielded from the positive (+) charge of the nucleus by the electrons in the inner energy levels. Basically those inner energy levels are insulating the ve- from the nucleus' positive charge. Across the period the shielding effect will stay the same because no new energy levels are being added. Down a group the shielding effect will increase because the number of inner energy levels are increasing.

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__**How to calculate the mass of a Chemical Reaction**:__
[|Calculate mass]

**(1 atom x 23 grams/mole Na) + (1 atom x 35.5 grams/mole Cl) = 58.5 grams/mole NaCl**
 * 1.) Molar masses of chemical compounds are equal to the sums of the molar masses of all the atoms in one molecule of that compound. ** If we have a chemical compound like NaCl, the molar mass will be equal to the molar mass of one atom of sodium plus the molar mass of one atom of chlorine. If we write this as a calculation, it looks like this:

For other compounds, this might get a little bit more complicated. For example, take the example of **Zinc Nitrate, or Zn( NO3)2**. In this compound, we have one atom of Zinc, two atoms of Nitrogen (one atom inside the brackets multiplied by the subscript two) and six atoms of Oxygen (three atoms in the brackets multiplied by the subscript two). The molar mass of Zinc Nitrate will be equal to __//(1 atom x 65 grams/mole of zinc) + (two atoms x 14 grams/mole of nitrogen) + (six atoms x 16 grams/mole of oxygen) = 189 grams/mole of zinc nitrate.//__ For all other compounds, the general idea is the same. Basically, you should know how to find the molar masses of any chemical compound now. In the next and final section, I'll give you some practice problems, followed by a solution key...[|calculating mass] Calculating the Molar Mass of magnesium phosphate
 * 2.) If you have a subscript in a chemical formula, then you multiply the number of atoms of anything next to that subscript by the number of the subscript. ** For most compounds, this is easy. For example, in **Iron (II) Chloride, or FeCl2**, you have one atom of iron and two atoms of cChlorine. The molar mass will be equal to __//(1 atom x 56 grams/mole Fe) + (2 atoms x 35.5 grams/mole of chlorine) = 127 grams/mole of iron (II) chloride.//__

In Magnesium Phosphate, there are three atoms of Magnesium, two atoms of Phosphorus, and eight atoms of Oxygen. (__The formula is Mg3( PO4)2__). The molar mass is then (__3 x 24 grams) + (2 x 31 grams) + (8 x 16 grams) = 262 grams/mole of Magnesium Phosphate__ []

Why Elements in a Group Have Similar Properties
So, why do elements in the same group have similar properties? It all has to do on what type of element an element is. **Group 1 elements are Alkali metals**. Alkali metals can __bond with group 17 elements to make a salt__. They are rarely in their own pure form because they're so reactive. They be cut with a butter knife (Yep, they're that soft). They must be stored with oil because if they react with O2...KABOOM!!!!!!Group 2 elements are alkaline earth metals. They're shiny solids and are harder than alkali metals. They don't easily dissolve in water. **Group 17 elements are Halogens**. It's the only group that elements from all three states of matter at room temperature (Fr and Cl are gases, Br is a liquid, and I and At are solids). They're the most reactive nonmetals and are always found combined in nature. They are also called salt formers. **Group 18 elements are Noble gases**. Because they already have __8 valence electrons (A full valence shell)__, they are less likely to form compounds. however, they can form compounds with elements of that same group. They are all mono atomic gases (Gases with one atom). **Groups 3-12 are Transition metals**. These elements are pretty colorful. Nickel is green, copper is blue, iron is red, orange, or brown, they're more colors for different transition metals. They're mush harder than group 1 or 2 elements. They usually have high melting or boiling points. They also can have many oxidation states. **Lanthanoids are Inner Transition metals**. They are silvery metals with high boiling points and can be radioactive. **Actinides are also Inner Transition metals**. All of them are radioactive. Only 3 are found in nature.

**<span style="color: blue; font-family: 'Arial','sans-serif'; font-size: 12pt;">[] **
<span style="-moz-background-clip: border; -moz-background-inline-policy: continuous; -moz-background-origin: padding; background: white none repeat scroll 0% 0%; line-height: normal; margin: 0in 0in 0pt;">**<span style="color: #333333; font-family: 'Verdana','sans-serif'; font-size: 12pt;">A mole is simply a unit of measurement. Units are invented when existing units are inadequate. Chemical reactions often take place at levels where using grams wouldn't make sense, yet using absolute numbers of atoms/molecules/ions would be confusing, too. ** <span style="-moz-background-clip: border; -moz-background-inline-policy: continuous; -moz-background-origin: padding; background: white none repeat scroll 0% 0%; line-height: normal; margin: 0.25in 0in 10pt;">**<span style="color: #333333; font-family: 'Verdana','sans-serif'; font-size: 12pt;">Like all units, a mole has to be based on something reproducible. A mole is the quantity of anything that has the same number of particles found in 12.000 grams of carbon-12. That number of particles is Avogadro's Number, which is roughly 6.02x1023. **

= Periodic Law =

==The periodic law states that elements are arranged in increasing atomic number and that their chemical and physical properties repeat in a regular pattern. An example is Hydrogen (H), Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), and Francium (Fr). How so They are all alkali metals and when you get back to group one, their properties repeat again. If you recall, alkali metals are good conductors of electricity.==

<span style="color: #000bff; font-family: 'Arial Black',Gadget,sans-serif; font-size: 130%;">HOW TO CALCULATE MOLES TO MASS AND MASS TO MOLES:


 * Well first off, one mole of a pure substance has a mass equal to its molecular mass. Therefore 2 moles would have a mass of 2** x **MM, 3 moles would have a mass of 3** x **MM, and so on and so on.**


 * Now on to the formula-**
 * Mass = n** x **MM**


 * n = moles of pure substance**
 * MM = molecular mass of a pure substance**


 * Other formulas that you can do are-**
 * n = mass** ÷ **MM**
 * MM = mass** ÷ **n**


 * <span style="color: #fa178d; font-family: 'Arial Black',Gadget,sans-serif; font-size: 120%;">EXPLAIN WHY ELEMENTS IN THE SAME GROUP HAVE SIMILAR PROPERTIES: **

_
 * <span style="color: #000000; font-family: Arial,Helvetica,sans-serif;">Chemically they are mostly similar because there valence electron structure is the same, they also have the same number of valence electrons. Since they have the same number of valence electrons they would also have similar chemical reactions/bonds with other elements. **

Describe how atomic radius changes from left to right across a period and from top to bottom within a group.

The atomic radius changes because it has to do with the number of energy shells increase and are increasing by the number of increasing number electrons.What leads to the increase of atomic radius are where the shells are located and how far away they are from the nucleus.


 * Why do Chemists use the mole as a way of counting atoms and molecules?**

Moles look complicated, but it is useful. How come? Scientists need a way of counting atoms and molecules accuratley. However, it is impossible to do that because they're tiny and there are so many of them. So, they created a method to make it easier. (Glencoe Science textbook)

___

Explain why elements in a group have similar properties.
Elements in the same group have similar properties because of a couple of things but there is one that plays a major role. The main reason/major role of one of those things is that elements in the same group have the same number of valence electrons (same number of electrons in the outermost shell).

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Ions are atoms which have gained or lost electrons. The ionization energy is the amount of energy it takes to detach one electron from a neutral atom. Some elements actually have several ionization energies. When this is the case, we refer to them as the "first ionization energy" or 'I', "second ionization energy" or 'I2', and so on. Notice that the energy variable follows I//i// where //i// is the orbital from which the electron is lost. Ionization is endothermic meaning that the atom or molecule increases its internal energy (takes energy from an outside source). The equation for the first ionization energy is shown below:
 * Ionization Energy **

The equation for the second ionization energy is: Ionization energy values are typically very high and follow trends throughout the periodic table. The IE increase from bottom to top and left to right in the periodic table. Read More: []
 * Na --> Na+ + //e//-**
 * Na+ --> Na2+ + //e//-**

** Definition Of Periodic Law: **


 * || **<span style="color: #00b050; font-family: 'Times New Roman','serif'; font-size: 22pt;">When arranged according to atomic number, elements show repeating, or periodic trends in their chemical and physical properties. ** ||
 * || **<span style="color: #00b050; font-family: 'Times New Roman','serif'; font-size: 22pt;">When arranged according to atomic number, elements show repeating, or periodic trends in their chemical and physical properties. ** ||

Read More: []

=** Shielding Effects: **= <span style="background-color: transparent; border: medium none; color: #000000; display: block; overflow: hidden; text-align: left; text-decoration: none;">The screening effect, or shielding effect, is how electrons in the same atom interact with each other. In a single-electron atom (in isolation), the electron is only interacting with the proton; in a multielectron atom, the electrons are both interacting with the proton(s), but also with each other. While electrons are attracted to the protons in the nucleus, they are repelled by the other electrons. This electron-electron repulsion decreases the attractive force of the protons on the electrons.

<span style="background-color: transparent; border: medium none; color: #000000; display: block; overflow: hidden; text-align: left; text-decoration: none;"> The shielding effect changes the effective nuclear charge -- effectively decreasing the true nuclear charge. This effect causes atoms to get smaller as you across a period (row) of the periodic table, as well as many other periodic trends observed in the periodic table.

<span style="background-color: transparent; border: medium none; color: #000000; display: block; overflow: hidden; text-align: left; text-decoration: none;"> Read more: []



The legend above shows group 1- Alkali Metals, group 2-Alkali Earth metals, group 3-12 are Transition metals, running along the "steps" are non-metals and other metals, group 17 is halogens, and group 18 is Inert Metals. Below in the f-block are the inner transition metals.