ch 5 & 6: bonding, formulas and naming notes. types of chemical bonds: a. ionic bonding...

Ch 5 & 6: Bonding, Formulas

and Naming

Notes

Types of Chemical Bonds:A. Ionic Bonding

1) Positively charged ions are attracted to negativelynegatively

charged ions, making a neutralneutral compound.2) Properties of Ionic Compounds:

a) high melting poinmelting pointsts. b) dissolve in water to form solutionssolutions that are

good conductorsconductors of electricity (electrolyteelectrolytess).

c) have a large electronegativityelectronegativity difference between elements.

d) usually form between metalsmetals and nonmetalsnonmetals.

3) The Octet Rule:

a) Atoms tend to gain or lose electrons in order to acquire a fullfull set of valencevalence electrons (stablestable octetoctet).

b) Atoms will transfertransfer electrons (e-) to each other in order to have a full set of valencevalence electrons.

c) When electrons are transferred, ionicionic bonds are formed.

Ions• Atoms can form ions by gaining or losing

electrons.– Metals tend to lose one or more electrons to form

positive ions called cations.

– Cations are generally named by using the name of the parent atom.

• Nonmetals tend to gain one or more electrons to form negative ions called anions.

Ions

• Anions are named by using the root of the atom name followed by the suffix –ide.

Ionic Bond Practice Tutorial

4) Types of Compounds:

a) Binary form from monatomic ions – have 1 cation and 1 anion.Ex) Mg+2 O-2

Ca+2 Cl-1MgO

CaCl2

Na +1Na +1

Na +1

O -2

O -2

+ 1 - 2 Not Balanced

2 + (- 2) = 0 Balanced Na2O

2 x +1 = +2 1 x -2 = -2

Al +3

O -2

Al +3

Al +3

O -2 O -2

O -2

+3 -2 Not Balanced

+ 6 + (- 6) = 0 Balanced Al2O3

2 x +3 = +6 3 x -2 = -6

4) Types of Compounds:

b) Tertiary form from polyatomic ions which consists of a group of atoms covalentlycovalently bonded with a singlesingle charge that bond ionically with other ions.Ex.

“ammonium sulfate” ,

NH4+1 SO4

-2

(NH4)2SO

4

Name this compound:

FeO

If that’s correct, name this:Fe2O3

How can we distinguish between these compounds?

What is the charge on the oxygen in each compound? Then what is the charge on the iron in each compound?

Fix the name of the first compound:

Iron oxide Iron (II) oxide

Iron (III) oxide

Fe+2 O-2

Fe+3 O-2

X

Ions

Ion Charges and the Periodic Table

5) Polyvalent Metals:

Some metals including the transitiontransition metals do not follow the octetoctet rule and may form more than 1 kind of cation. These ions are named with romanroman numeralsnumerals to distinguish between them.Ex) Fe+2 iron (II) read “iron two”

Fe+3 iron (III) read “iron three” FeCl2 iron (II) chloride

FeCl3 iron (III) chloride

Copper (I) sulfate Copper (II) phosphate

Cu2SO4

Cu3(PO4)2

6) Lewis Dot Diagrams for elements:

Element# of val. Electrons

Dot Diagram

Li 1 Li

N 5

Be 2

F 7

Ne 8

Au 2

C 4

Electron Dot Diagram for Atoms and Ions

7) Lewis-dot diagram for sodium chloride:

[Na+] [ -]

B. Covalent Bonding

1) Covalent Bonds are formed by sharingsharing pairs of

electrons between 2 atoms. 2) Usually formed between two nonmetalsnonmetals with

a lowlow electronegativity difference.3) Molecules:

a) a group of atoms held together by covalentcovalent

bondsb) molecular substance – contains moleculesmolecules

4) Naming: a) uses prefixes: 1 mono- 4 tetra- 7 hepta- 10

deca- 2 di- 5 penta- 8 octa-

3 tri- 6 hexa- 9 nona-

b) end in “ide”c) More electronegative element is written lastlastd) Only use a prefix on the first element if it is

more than oneone.e) Always use a prefix for the secondsecond elementelement.Ex) water H2O dihydrogen monoxidedihydrogen monoxide

smog NO2 nitrogen dioxidenitrogen dioxide

5) Types of formulas for covalent bondinga) Molecular Formula shows how manymany

atoms make up a compoundcompound.ex. CHCH44 & HH22OO

b) Structural Formula shows how the atoms are bondedbonded to each other.

ex.

1. Uses 2 dotsdots to show an unshared pair of

electronselectrons.2. Uses dashesdashes to represent covalent bonds (a

shared pair of electrons) in a structural formula.3. The octetoctet rule should be satisfied for each

element in the compound.c) Empirical Formula is the lowestlowest whole

number ratioratio of all the elements in the compound.

Ex) C6H6= CH

C6H12O6= CH2O

6) Multiple Bonds – can be used to satisfy the octet rule

Single Bonds – Share 11 pair of electrons.

Ex) methane or phosphorous trichloride

Double Bonds – Share 22 pairs of electrons.

Ex) formaldehyde, CH2O

Triple Bonds – Share 33 pairs of electrons (strongeststrongest bond).Ex) ethyne, C2H2

8) Properties of Covalent Bondsa) Low meltingmelting points, brittlebrittle, strong odorodor,

poor conductorsconductors of electricity.b) Polar Bonds – form between elements with

largelarge differences in electronegativity. These have an unevenuneven sharing of electrons.

Ex) water

partial negative side

partial positive side

c) Nonpolar bonds – exert equalequal pullpull on the electrons.

Ex) O2

9) Electronegativity Chart is used to determine bond type

non polar covalent polar covalent ionic bonds

0 0.4 1.9 4.0

even sharing - no charge

Ex) OO22

uneven sharing – slight charge on molecule

Ex) HH22OO

electrons transferred – forms ions

Ex) NaClNaCl

Types of BondsTypes of Bonds

C. Ionic & Covalent Bonds Summary:

Ionic Bonding Covalent Bondingmetal-nonmetal nonmetal-nonmetal

e- transferred e- shared

large electronegativity difference (>1.9)

electronegativity difference (0 1.9)

ions formed no ions

written cation (+) anion (-)more electronegative element written last

name cation - name anion use # prefixes/ends in ide

forms ionic compound (formula unit) in a crystal lattice

forms molecules

Written with a chemical or empirical formula

Written with a molecular or structural formula

NaCl – sodium chloride CCl4 – carbon tetrachloride

[Na+] [ -]

How Atoms Bond Video Clip

carbon tetrachloride

D. Acids:1) A molecular compound that

dissolves in water to produce H H ionsions and a characteristic anionanion.

2) In water, acids behave like ionicionic compounds.

3) Most acid formulas begin with HH. (Except organic acids) “ COOHCOOH”

4) The number of hydrogens in the formula depends upon the chargecharge of the anion.

5)Types of Acids

a.) Organic Acids contain the carboxyliccarboxylic group,

-COOH or

Ex) CHCH33COOH acetic acid COOH acetic acid (vinegar)(vinegar)

(or HC(or HC22HH33OO22))

b.) Binary Acids contain hydrogenhydrogen and 1 type of anionanion.A two-word name is used for binary acids.

1st word: prefix is “hydro”root is formed from the anionanion suffix “ide” is changed to “ic”

2nd word: is “acid”

Ex) HCl anion is chloride hydrochloric acidPrefix root suffix

HBr anion is bromide hydrobromic acidhydrobromic acid H3P anion phosphide hydrophosphoric hydrophosphoric

acidacid

c.) Oxo (Tertiary) Acids: contain oxygenoxygen within a polyatomic ion.A two-word name is used for oxo acids.

H2SO4 sulfate sulfuric acid

H2SO3 sulfite sulfurous acid

sulfur or phosphor (to sound better) 2nd word is “acid”If you “ate” something you don’t like, you

say “ic”“ite-ous”

HNO3 anion is nitrate nitric acid

root suffix

H3PO3 anion is phosphite phosphorous acid

Nitrous acid, anion is nitrite formula is: HNO2

Phosphoric acid, anion is phosphate

formula is: H3PO4

E. Hydrates:1.) Ionic compounds that absorb H2O into their

solid structures.Ex) magnesium sulfate heptahydratemagnesium sulfate heptahydrate (epsom

salt) Formula: MgSO4 7H2O

2.) Anhydrous substance – substance without substance without water water MgSOMgSO44

Ex) CuSO4 • 5H2O copper (II) sulfate pentahydratecopper (II) sulfate pentahydrate (bright blue)

CuSO4 – anhydrate (light blue/white)