Covalent+Compounds,+Nomenclature+and+Bonding

How to Name Chemical Compounds
[|http://facstaff.gpc.edu/~pgore/PhysicalScience/Naming-chemical-compounds.html]

How Elements Bond Slideshow
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Why Compounds Bond Music Video
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Nomenclature Diagram(the basic language of Chemistry
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[|polar and non-polar molecules]

//media type="youtube" key="X9FbSsO_beg?fs=1" height="385" width="480"How to Write Covalent Compounds: http://www.youtube.com/watch?v=ZTMHbKtgI-M&feature=BF&list=PL3ABD5DB7B56A641F&index=13 //
[|naming and writing of covalent compounds]

=//Properties of metals//=

Some properties of metals :


 * //metals tend to lose electrons in reactions//
 * //metals are ductile and malleablehttp://www.youtube.com/watch?v=ZTMHbKtgI-M&feature=BF&list=PL3ABD5DB7B56A641F&index=13
 * metals conduct heat and electricity
 * metals have a shiny (lustrous) appearance

A material that possesses toughness will withstand tearing or shearing and may be stretched or otherwise deformed without breaking. Density is the weight of a unit volume of a material. Metals have the ability to be drawn into thin, cohesive strands (wires) Metals can be flattened (hammered or rolled) into thin sheets.
 * Characteristics of Metals**
 * Toughness**
 * Density**
 * Ductility**
 * Malleability**

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 * Fusibility**

=hhChemical Formulas:=

Water- H20 Carbon Monoxide: CO Carbon Dioxide:CO2 Sulfur Dioxide:SO2 Carbon Tetrafluoride: CF4

=//To Determine a molecule's shape using the VSEPR Theory://= //1. Draw the Lewis Dot structure of the molecule.// //2. Use the Valence Shell Electron Pair Repulsion Theory, which says: the electrons that have formed bonds and the lone-pair electrons repel away from each other. // //3. Find the Steric Number(SN): Do this for each atom that has bonded with one or more atoms. // //SN= the number of bonds + the number of lone pairs. // //If the SN is two, then the shape is LINEAR. If the SN is three, then the shape is BENT, this also goes for four. // //The shapes change as the SN rises. //
 * __ AgIO3 __ || __ [|silver iodate] __ ||  ||
 * __ AgMnO4 __ || __ [|silver permanganate] __ ||  ||
 * __ AgN3 __ || __ [|silver azide] __ ||  ||
 * __ AgNO3 __ || __ [|silver nitrate] __ || [] ||

=//The Common Physical Properties of of Covalent Compounds://=

//Solubility: -Insoluble in water//
// -Non-electrolyte (They do not conduct electricity) // // LOW Melting Point // // Conductivity: Non-Polar Covalent Compounds do not conduct electricity. // // -Polar Covalent Compounds conducts a small amount of electricity. // // -Covalent Compounds are hard compounds. //

=//Q- Why atoms form covalent bonds? //=

//﻿A- Atoms form covalent bonds because they are nonmetals.//
//__** A- Atoms form covalent bonds through the sharing of valence electrons. **__//

A- Covalent bond: a chemical bond that involves sharing a pair of electrons between atoms in a molecule
Empirical formula: a chemical formula showing the ratio of elements in a compound rather than the total number of atoms molecular formula: a chemical formula based on analysis and molecular weight polar molecule: in chemistry, polarity refers to a separation of electric charge leading to a molecule having an electric dipole. ..  .  **Q- Explain what happens when a covalent bond forms between two nonmetals** A- Examples of nonmetals: H, C, N, O, F, Si, P, S, Cl, etc... When these elements are bonded together to form compounds, they form covalent bonds - sometimes "polar covalent", but still generally covalent. [|http://www.elmhurst.edu/~chm/vchembook/144Acovalent.html]

A- binary covalent compound is composed of two different nonmetal elements. For example, a molecule of chlorine trifluoride, ClF3 contains 1 atom of chlorine and 3 atoms of fluorine. **Rule 1.** The element with the lower group number is written first in the name; the element with the higher group number is written second in the name **Rule 2.** If both elements are in the same group, the element with the higher period number is written first in the name. **Rule 3.** The second element in the name is named as if it were an anion, i.e., by adding the suffix //-ide// to the name of the element. **Rule 4.** Greek prefixes (see the Table provided at the bottom of this page) are used to indicate the number of atoms of each nonmetal element in the chemical formula for the compound.
 * Q- Name binary covalent compounds**

**Q- Give a compound's molecular formula determine its empirical formula.**
====Ionic Bond-a chemical bond in which one atom loses an electron to form a positive ion and the other atom gains an electron to form a negative ion ==== [|wordnetweb.princeton.edu/perl/webwn]

Q- Draw Lewis Dot Diagrams to show covalent bonding.?
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=**Q: Recognise polar and non-polar molecules?**=

=**A:**more information here=

=Q:Use VSEPR theory to determine a given molecule's shape=

=A:more infornation= __**VESPR Model video**__ [] This video describes how to predict the molecular geometry by describing how electron pairs bond.


 * __Comparision Between Covalent and Ionic Compund Properties__**

Ionic Compounds

 * 1) Crystalline solids (made of ions)
 * 2) High melting and boiling points
 * 3) Conduct electricity when melted
 * 4) Many soluble in water but not in nonpolar liquid**__Covalent Compounds__**
 * 5) ==Covalent Compounds==

> || A binary covalent compound is composed of two different nonmetal elements. For example, a molecule of chlorine trifluoride, ClF3 contains 1 atom of chlorine and 3 atoms of fluorine. || > > > > > **Rule 1.** The element with the lower group number is written first in the name; the element with the higher group number is written second in the name. > > > > > //**Exception: when the compound contains oxygen and a halogen, the name of the halogen is the __first__ word in the name.**// > > > > > **Rule 2.** If both elements are in the same group, the element with the higher period number is written first in the name. > > > > > **Rule 3.** The second element in the name is named as if it were an anion, i.e., by adding the suffix //-ide// to the name of the element. > > > > > **Rule 4.** Greek prefixes (see the Table provided at the bottom of this page) are used to indicate the number of atoms of each nonmetal element in the chemical formula for the compound. > > > > > //**Exception: if the compound contains one atom of the element that is written first in the name, the prefix "mono-" is __not__ used.**// > 2. Why atoms form covalent bonds? > A **covalent bond** is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms, and other covalent bonds. In short, the stable balance of attractive and repulsive forces between atoms when they share electrons is known as covalent bonding. > > > > > []
 * 1) GaGases, liquids, or solids (made of molecules)
 * 2) Low melting and boiling points
 * 3) Poor electrical conductors in all phases
 * 4) Many soluble in nonpolar liquids but not in water
 * 5) []
 * Rules for Naming Binary Covalent Compounds ||

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//SHS9 Update-12-23-10// //A quiz that asks you to name covalent and ionic bonds, very similiar to our previous classwork.// //[]//

=﻿= =Why do atoms form convalent bonds?=

Atoms form covalent bonds through the sharing of valence electrons. As every atom's preference is to have a stable octet (a full valence), nonmetal compounds can share with one another to help achieve this. A covalent bond is an intramolecular force holding atoms in place, caused by this sharing. The fashion in which this is done is actually quite brilliant and simple:

The valence orbital can form hybridized bonds - bonds that are perfectly designed to hold each atom in place. These bonds follow a pattern known as VSEPR (Valence Shell Electron Pair Repulsion) Theory; basically electrons in each orbital will position themselves as far apart from one another as possible, reaching an optimum configuration for stability.

[]


 * A:** []

= ﻿What happens when a convalent bond forms between two nonmetals? =

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= Q:Use the sea of electron model for metallic bonding to explain properties of metals such as conductivity and malleability? =

= A: =

= A:media type="youtube" key="Oh0nv3ErjqU?fs=1" height="385" width="480" =

//__** A: **__// <span style="font-family: arial,verdana,sans-serif; font-size: small; line-height: 16px;">In simple terms metallic bonding is referred to as bonding in metal atoms. It is also defined as interaction between metal nuclei and the delocalized electrons. Delocalized electrons are also called as conduction electrons. Metals nuclei are the positive ions and so Metallic bonding can be imagined as Sea of electrons in which positive metal ions are embedded. Positive metal ions are called as Kernels. Thus metallic bonding can be summarized as: - The force of attraction which binds together the positive metal ions or Kernels with th electrons within its sphere of influence. <span style="font-family: arial,verdana,sans-serif; font-size: small; line-height: 16px;">media type="custom" key="7825897"

=Q:Draw Lewis Dot Diagrams to show covalent bonding.?=

=A:=

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Covalent Compounds, Nomenclature and Bonding A game to help your bonding\naming.

// A: // // Pick a Central Atom //

> //Once you have selected the central atom, write it down and connect the other atoms to it with a single bond. You may change these bonds to become double or triple bonds as you progress.// > > > > > //Once the electrons have been placed, put brackets around the entire structure. If there is a charge on the molecule, write it as a superscript on the upper right, outside of the bracket.//
 * 1) //Start your structure by picking a central atom and writing its [|element symbol]. This atom will be the one with the lowest [|electronegativity]. Sometimes it's difficult to know which atom is the least electronegative, but you can use the [|periodic table trends] to help you out. Electronegativity typically increases as you move from left to right across the periodic table and decreases as you move down the table, from top to bottom. You can consult a table of electronegativities, but be aware different tables may give you slightly different values, since electronegativity is calculated.//
 * 1) //Count ElectronsLewis electron dot structures show the [|valence electrons] for each atom. You don't need to worry about the total number of electrons, only those in the the outer shells. The [|octet rule] states that atoms with 8 electrons in their outer shell are stable. This rule applies well up to period 4, when it takes 18 electrons to fill the outer orbitals. 32 electrons are required to fill the outer orbitals of electrons from period 6. However, most of the time you are asked to draw a Lewis structure, you can stick with the octet rule.//
 * 1) //Place Electrons around AtomsOnce you have determined how many electrons to draw around each atom, start placing them on the structure. Start by placing one pair of dots for each pair of valence electrons. Once the lone pairs are placed, you may find some atoms, particularly the central atom, don't have a complete octet of electrons. This indicates there are double or possibly triple bonds. Remember, it takes a pair of electrons to form a bond.//

=Q: //Give a compound's molecular formula determine its empirical formula://=

=//A:media type="youtube" key="gfBcM3uvWfs?fs=1" height="385" width="640"//=

Describe common physical properties of covalent compounds including solubility, melting point, hardness and conductivity.

For another example watch this video on Youtube

Use the sea of electron model for metallic bonding to explain properties of metals such as conductivity and malleability.

for another example watch this video on youtube.com

Define key terms: Covalent Bond, Empirical Formula, Molecular formula, Polar molecule

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Q: Name binary covalent compounds? A: media type="youtube" key="RzLp8acitf0?fs=1" height="385" width="480"

A: Binary covalent compounds are compounds made up of only two elements, such as carbon dioxide. Prefixes are used in the names of binary compounds to indicate the number of atoms of each nonmetal present.

The following table lists the most common prefixes for binary covalent compounds. Common Prefixes for Binary Covalent Compounds ||~ Number of Atoms ||~ Prefix || In general, the prefixmono-is rarely used. Carbon monoxide is one of the few compounds that uses this prefix. Take a look at the following examples to see how to use the prefixes when naming binary covalent compounds (the prefixes appear in bold). Note that chemists try to avoid putting anaand anotogether with the oxide name, as in decaoxide, so they normally drop theaoff the prefix. carbondioxide: tetraphosphorusdecoxide: sulfurtrioxide: dinitrogentetroxide: This naming system is used only with binary, nonmetal compounds, with one exception. The following compound is commonly called manganese dioxide.
 * 1 || mono- ||
 * 2 || di- ||
 * 3 || tri- ||
 * 4 || tetra- ||
 * 5 || penta- ||
 * 6 || hexa- ||
 * 7 || hepta- ||
 * 8 || octa- ||
 * 9 || nona- ||
 * 10 || deca- ||



<span style="color: #f15bbe; font-family: Georgia,serif;">[]
-**Explain what happens when convalent bond forms between two nonmetals:** Remember that hydrogen's electron is in a 1s orbital - a spherically symmetric region of space surrounding the nucleus where there is some fixed chance (say 95%) of finding the electron. When a covalent bond is formed, the atomic orbitals (the orbitals in the individual atoms) merge to produce a new molecular orbital which contains the electron pair which creates the bond.

Four molecular orbitals are formed, looking rather like the original sp3 hybrids, but with a hydrogen nucleus embedded in each lobe. Each orbital holds the 2 electrons that we've previously drawn as a dot and a cross. The principles involved - promotion of electrons if necessary, then hybridisation, followed by the formation of molecular orbitals - can be applied to any covalently-bound molecule. The chemical formulas for certain common substances, such as water, carbon monoxide, carbon dioxide, sulfur dioxide, carbon tetrafloride: Water (H2O), Carbon monoxide (CO), Carbon dioxide (**CO2**), sulur dioxide ( SO2), Carbon tetraflouride (CF4)
 * **-Binary covalent compounds:A binary covalent compound is composed of two different elements (usually nonmetals). For example, a molecule of chlorine trifluoride, ClF3 contains 1 atom of chlorine and 3 atoms of fluorine.
 * **-Binary covalent compounds:A binary covalent compound is composed of two different elements (usually nonmetals). For example, a molecule of chlorine trifluoride, ClF3 contains 1 atom of chlorine and 3 atoms of fluorine.
 * **-Common physical properties of convalent compounds including solubility, melting point, hardness and conductivity:
 * **-Common physical properties of convalent compounds including solubility, melting point, hardness and conductivity:

Soft (Compared to Ionic Compounds
<span style="background-color: transparent; color: #000000; display: block; overflow-x: hidden; overflow-y: hidden; text-align: left; text-decoration: none;">**﻿****﻿**- A compound's molecular formula determine its empirical formula: <span style="background-color: transparent; color: #000000; display: block; overflow-x: hidden; overflow-y: hidden; text-align: left; text-decoration: none;">Because an empirical formula is the simplest form of a compound, we know that the molecular formula contains more atoms than it does. Since we are given the molar mass, we can use this formula. <span style="background-color: transparent; color: #000000; display: block; overflow-x: hidden; overflow-y: hidden; text-align: left; text-decoration: none;">x ( MM of empirical formula ) = MM of molecular formula <span style="background-color: transparent; color: #000000; display: block; overflow-x: hidden; overflow-y: hidden; text-align: left; text-decoration: none;">MM of empirical formula = 12(2) + 1(6) + 16 = 46 <span style="background-color: transparent; color: #000000; display: block; overflow-x: hidden; overflow-y: hidden; text-align: left; text-decoration: none;">MM of molecular formula = 138 <span style="background-color: transparent; color: #000000; display: block; overflow-x: hidden; overflow-y: hidden; text-align: left; text-decoration: none;">46x = 138 <span style="background-color: transparent; color: #000000; display: block; overflow-x: hidden; overflow-y: hidden; text-align: left; text-decoration: none;">x= 138 / 46 <span style="background-color: transparent; color: #000000; display: block; overflow-x: hidden; overflow-y: hidden; text-align: left; text-decoration: none;">x=3 <span style="background-color: transparent; color: #000000; display: block; overflow-x: hidden; overflow-y: hidden; text-align: left; text-decoration: none;">Therefore, the molecular formula is 3(C2H6O) that is C6H18O3

<span style="background-color: transparent; color: #000000; display: block; overflow-x: hidden; overflow-y: hidden; text-align: left; text-decoration: none;"><span style="background-color: transparent; color: #000000; display: block; overflow: hidden; text-align: left; text-decoration: none;">- Propeties of matals such as conductivity and malleability: Malleability <span style="background-color: transparent; color: #000000; display: block; font-family: Times New Roman; overflow: hidden; text-align: left; text-decoration: none;">A metal that can be hammered, rolled, or pressed <span style="background-color: transparent; color: #000000; display: block; overflow: hidden; text-align: left; text-decoration: none;"> into various shapes without cracking or breaking or other detrimental effects is said to be malleable. This property is necessary in sheet metal that is to be worked into curved shapes such as cowlings, fairings, and wing tips. Copper is one example of a malleable metal Conductivity <span style="background-color: transparent; color: #000000; display: block; font-family: Times New Roman; overflow: hidden; text-align: left; text-decoration: none;">Conductivity is the property that enables a metal to <span style="background-color: transparent; color: #000000; display: block; overflow: hidden; text-align: left; text-decoration: none;"> carry heat or electricity. The heat conductivity of a metal is especially important in welding, because it governs the amount of heat that will be required for proper fusion. Conductivity of the metal, to a certain extent, determines the type of jig to be used to control expansion and contraction. In aircraft, electrical conductivity must also be considered in conjunction with bonding, which is used to eliminate radio interference. Metals vary in their capacity to conduct heat. Copper, for instance, has a relatively high rate of heat conductivity and is a good electrical conductor - Lewis dot diagram to show convalent bonding: -Use VSEPR theory to determine a given molecule's shape:

Q:Give a compound's molecular formula determine its empirical formula? A:media type="youtube" key="OaV4PSLV0Hs?fs=1" height="385" width="480"

Diagram || # of Lone Pairs Around Central Atom || # of Bonding Electron Groups Around Central Atom || Name of Shape || *Shape Diagram and Bond Dipoles || Polar || planar || || no || (bent) || || yes || [] ** *NOTE: **
 * STEREOCHEMISTRY OF SOME COMMON MOLECULES ||
 * Compound || Lewis
 * C2H2 || **H : C ::: C : H** || 0 || 2 || linear || [[image:http://users.stlcc.edu/gkrishnan/ethynedip.gif width="139" height="139" align="center"]] || no ||
 * C2H4 || [[image:http://users.stlcc.edu/gkrishnan/ethene2dot.gif width="121" height="121" align="center"]] || 0 || 3 || trigonal
 * CH4 || [[image:http://users.stlcc.edu/gkrishnan/methane2dot.gif width="115" height="115" align="center"]] || 0 || 4 || tetrahedral || [[image:http://users.stlcc.edu/gkrishnan/mthane2dip.gif width="130" height="134" align="center"]] || no ||
 * NH3 || [[image:http://users.stlcc.edu/gkrishnan/ammonia2dot.gif width="111" height="111" align="center"]] || 1 || 3 || pyramidal || [[image:http://users.stlcc.edu/gkrishnan/ammonia2dip.gif width="117" height="123" align="center"]] || yes ||
 * H2O || [[image:http://users.stlcc.edu/gkrishnan/water2dot.gif width="120" height="120" align="center"]] || 2 || 2 || v-shaped

A: **Examples of Empirical and Molecular Formula**

If carbon and hydrogen are present in a compound in a ratio of 1:2, the empirical formula for the compound is CH2. The empirical formula mass of this compound is: 12.0 + (2 x 1.0) = 14.0 g/mol If we know the molecular mass of the compound is 28.0 g/mol then we can find the molecular formula for the compound. MM = n x empirical formula mass 28.0 = n x 14.0 n = 2 So the molecular formula for the compound is 2 x empirical formula, ie, 2 x (CH2) which is C2H4 There are many compounds that can have the empirical formula CH2. These include:
 * C2H4(ethene or ethylene) molecular mass=28.0g/mol and n=2
 * C3H6(propene or propylene) molecular mass=42.0g/mol and n=3
 * C3H6(cyclopropane) molecular mass=42.0g/mol and n=3
 * C4H8(butene or butylene) molecular mass=56.0g/mol and n=4
 * C4H8(cyclobutane) molecular mass=56.0g/mol and n=4

Example 1
A compound is found to contain 47.25% copper and 52.75% chlorine. Find the empirical formula for this compound.


 * ~ element ||~ Cu ||~ Cl ||
 * ~ mass in grams || 47.25 || 52.75 ||
 * ~ r.a.m || 63.6 || 35.5 ||
 * ~ moles = mass ÷ r.a.m || 47.25 ÷ 63.6 = 0.74 || 52.75 ÷ 35.5 = 1.49 ||
 * ~ divide throughout by lowest number || 0.74 ÷ 0.74 = 1 || 1.49 ÷ 0.74 = 2.01 = 2 ||

Empirical formula for this compound is CuCl2

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=Q: Why atoms form covalent bonds?=

Rules for Naming Binary Covalent Compounds
A binary covalent compound is composed of two different elements (usually nonmetals). For example, a molecule of chlorine trifluoride, ClF3 contains 1 atom of chlorine and 3 atoms of fluorine.

**Rule 1.** The element with the lower group number is written first in the name; the element with the higher group number is written second in the name.**//Exception: when the compound contains oxygen and a halogen, the name of the halogen is the __first__ word in the name.//**

**Rule 2.** If both elements are in the same group, the element with the higher period number is written first in the name.

**Rule 3.** The second element in the name is named as if it were an anion, i.e., by adding the suffix //-ide// to the root of the element name (e.g., **fluor**ine = F, "**fluor**ide" = F-; **sulf**ur = S, "**sulf**ide" = S2-).

**Rule 4.** Greek prefixes are used to indicate the number of atoms of each element in the chemical formula for the compound. **//Exception: if the compound contains one atom of the element that is written first in the name, the prefix "mono-" is __not__ used.//**

//Note: when the addition of the Greek prefix places two vowels adjacent to one another, the "a" (or the "o") at the end of the Greek prefix is usually dropped; for example, "**nona**oxide" would be written as "**non**oxide", and "**mono**oxide" would be written as "**mon**oxide". The "i" at the end of the prefixes "di-" and "tri-" are never dropped.// []

A: is based upon electron-pair sharing and is the attraction between two atoms that share electrons. A single covalent bond is a bond in which two atoms are held together by sharing two electrons. <span style="display: block; font-family: Arial; font-size: medium; line-height: normal; text-align: justify;">Each positive nucleus is attracted toward the region of high electron density between them:



<span style="display: block; font-family: Arial; font-size: medium; line-height: normal; text-align: center;">1//s//2 2//s//2 2//p//6 3//s//2 3//p//2 3//p//2 3//p//1 3//p//1 3//p//2 3//p//2 3//s//2 2//p//6 2//s//2 1//s//2 <span style="display: block; font-family: Arial; font-size: medium; line-height: normal; text-align: justify;">The bonded atoms come close enough together for their electron clouds to overlap. <span style="display: block; font-family: Arial; font-size: medium; line-height: normal; text-align: justify;">Covalent bonds form between atoms when ionic or metallic bonding is unlikely because the gain or loss of electrons requires large amounts of energy. <span style="display: block; font-family: Arial; font-size: medium; line-height: normal; text-align: justify;">The most obvious example is the bonding of nonmetal atoms with themselves (as in Cl2, H2, O2) and with each other (as in HCl, H2O, BrF3). <span style="display: block; font-family: Arial; font-size: medium; line-height: normal; text-align: justify;">In bond formation, the semiconducting elements tend to behave like the nonmetals, forming covalent bonds in many compounds with nonmetals (eg. BCl3, SiF4). <span style="display: block; font-family: Arial; font-size: medium; line-height: normal; text-align: justify;">The number of valence electrons and the octet rule govern the formation of many covalent compounds. For second-period elements (Li to F), which have only //s// and //p//orbitals available, 8 is the maximum number of valence electrons that can be accommodated. <span style="display: block; font-family: Arial; font-size: medium; line-height: normal; text-align: justify;">Many stable compounds also exist in which the central atom is not surrounded by 8 electrons. Most of these fall into three categories; <span style="display: block; font-family: Arial; font-size: medium; line-height: normal; text-align: justify;">1. //Certain molecular compounds of beryllium, boron, or aluminium//. Be has two valence electrons (2//s//2) while B (2//s//22//p//1) and Al (3//s//23//p//1) have three. Therefore, these elements can form compounds with two or three covalent bonds, respectively, with no remaining unshared electron pairs. <span style="display: block; font-family: Arial; font-size: medium; line-height: normal; text-align: justify;">**Example:**

<span style="display: block; font-family: Arial; font-size: medium; line-height: normal; text-align: justify;">2. //Certain molecular compounds of phosphorus, sulfur, chlorine, or other elements from the third period and beyond//. In atoms with //n// = 3 or more, //d// orbitals are available. For elements of the 3rd to 6th periods, the outermost //d// subshells are empty. Therefore, these elements can accommodate more than 8 valence electrons if some of them utilise vacant outermost //d// subshells.

<span style="display: block; font-family: Arial; font-size: medium; line-height: normal; text-align: justify;">**Example:**



<span style="display: block; font-family: Arial; font-size: medium; line-height: normal; text-align: justify;">3. //Compounds with unpaired electrons//. Some compounds exist in which one or more electrons remain unpaired. In such cases the total of the valence electrons of the central atom and the atoms bonded to it is an odd number. Chlorine dioxide, for example, has a total of 19 valence electrons (6 from each of the two oxygen atoms and 7 from the chlorine atom). <span style="display: block; font-family: Arial; font-size: medium; line-height: normal; text-align: justify;">A reasonable Lewis structure would be;

<span style="display: block; font-family: arial,helvetica,sans-serif; font-size: 13px; line-height: 19px; text-align: justify;">[|http://www.cartage.org.lb/en/themes/sciences/chemistry/inorganicchemistry/informationbonding/covalentbond/covalentbond.htm]

<span style="display: block; font-family: arial,helvetica,sans-serif; font-size: 13px; line-height: 19px; text-align: justify;">Q: Use VSEPR theory to determine a given molecule's shape?
=<span style="display: block; font-family: arial,helvetica,sans-serif; font-size: 13px; line-height: 19px; text-align: justify;">A:media type="youtube" key="0Mn_CXvXElM" height="390" width="480" =

__//A://__

** First, you must draw the Lewis dot structure of the molecule **. If you don't know how, look at the Related Questions link to the left of this answer for step-by-step instructions on how to do that. Once you have a completed structure, you are ready to continue!

To determine the shape of a molecule, or its geometry, we use something called ** VSEPR ** Theory, which is short for Valence Shell Electron Pair Repulsion Theory. It's actually pretty simple! In short, it says that the electrons in bonds and lone-pairs around an atom will stay as far away from each other as possible! That's it! OK-- but how do we use it?

The first thing you have to figure out is something called the ** steric number **, which I'll abbreviate SN. We are going to do this for each atom that has more than one atom bonded to it. To do this, we look at our Lewis dot structure and use this formula:

** Steric number = SN = the number of bonds + the number of lone pairs ** NOTE: the number of bonds just counts each bond once, even if it is a double or triple bond. Don't worry about those yet... we'll get to that later!

Now, the steric number (or SN) will tell us the geometry of the molecule. I'm going to make a distinction between what I call the "geometry" and what I call the "shape." You'll see what I mean, but not all teachers will do this. The geometry is determined by how many things are attached to the atom, including both bonded atom, and lone pairs. The geometry determines the angles between the bonded atoms and the lone pairs. However, the shape is different. When you look at a molecule, you see where the atoms are, not the lone pairs. So the shape is given by where the atoms are located. But the lone pairs often determine where the atoms are located, so first we have to find the geometry, and then we use that to get the shape! Don't worry... I'll explain this more.

As I said, the steric number (or SN) determines the geometry of the molecule. So, here they are (if something has SN = 1, it's easy! It has to be linear!):

SN = 2 ---> geometry is linear (with an angle of 180°)

SN = 3 ---> geometry is trigonal planar (with all angles equal to 120°)

SN = 4 ---> geometry is tetrahedral (with all angles equal to 109.5°)

SN = 5 ---> geometry is trigonal bipyramidal (angles of 90° and 120°)

SN = 6 ---> geometry is octahedral (all angles equal 90°)

OK, now we'll use the geometry to determine the shape. It gets a bit tricker now. We now have to count how many bonds and how many lone pairs there are around each atom (again double and triple bonds only count as one bond). For each value of SN above, the can be several possibilities. I will go through them one by one.

** To help you, look at the Web Links to the left of this answer for pictures. **

The table at the bottom of the linked Wikipedia page will be especially useful here. Notice the steric number is listed on the left. They use the same idea of geometry versus shape, but the name of the shape is listed directly under each molecule in the chart.

The Ausetute page is also good, except note that they don't call the steric number the "Total number of electron pairs," and they call the geometry the "Arrangement of electron pairs."

** SN = 2 ** -- 1 bond, 1 lone pair: The shape is ** linear **! There is only one thing attached! -- 2 bonds: The shape is ** linear **. There is one atom in the middle, with two atoms on either side, all in a straight line. The angle formed is 180°.

** SN = 3 ** -- 2 bonds, 1 lone pair: The shape is ** bent **. There is one atom with two atoms attached to it, coming out in a V-shape. The angles formed are approximately 120° and 240° -- 3 bonds: The shape is ** trigonal planar **. There is one atom with three atoms around it, all in the same plane. The angle between each atom is 120°.

** SN = 4 ** -- 2 bonds, 2 lone pairs: The shape is ** bent **. There is one atom with two atoms attached to it, coming out in a V-shape. The angles formed are approximately 109° and 251° -- 3 bonds, 1 lone pair: The shape is ** trigonal pyramidal **. There is one atom with three atoms bonded to it, but they are all lower than it (like a camera on a tripod), and there is a lone pair sticking straight up. The angles between the bonded atoms are all approximately 109° -- 4 bonds: The shape is ** tetrahedral **. There is one atom in the middle, with four atoms around it. The angles between each atom is 109.5°

SN = 5

There are many possibilities here, but I will only do one:

-- 5 bonds: The shape is ** trigonal bipyramidal **. Other shapes possible for SN=5 are ** T-shaped, see-saw, linear, and bent. **

SN = 6 Again, there are many possibilities here, but these two are most common: -- 4 bonds and 2 lone pairs: The shape is ** square planar **, with 90° and 180° angles between each of the bonded atoms, all in the same plane -- 6 bonds: The shape is ** octahedral **, with 90° between all bonds. You can also have these shapes for SN = 6: ** square pyramidal, T-shape, and linear. **

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vsper theory