Ch 6: Bonding, Formulas and Naming

Notes

Bonding ObjectivesChem 5.0: Bonding, Formulas and Naming - OBJECTIVES

• Describe Ionic Bonding Theory.

• Describe Covalent Bonding Theory.

• Write formulas and names for ionic compounds including binary, tertiary and polyvalent.

• Write formulas and names for molecules (covalent compounds.)

• Write formulas and names for hydrates.

• Write formulas and names for binary and tertiary acids.

• Write Lewis-Dot structures for ionic compounds.

• Write structural formulas for covalent compounds.

• Describe electronegativity and how it affects bond type – ionic, polar covalent and nonpolar covalent.

Types of Chemical Bonds:A. Ionic Bonding

1) Positively charged ions are attracted to negatively

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

a) high melting points. b) dissolve in water to form solutions that are

good conductors of electricity (electrolytes).

c) have a large electronegativity difference between elements.

d) usually form between metals and nonmetals.

3) The Octet Rule:

a) Atoms tend to gain or lose electrons in order to acquire a full set of valence electrons (stable octet).

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

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

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

Writing Ionic Formulas

*This may not be on your notes, but if you don’t know how to do this it will severely affect your grade*

• When chemical symbols are by them selves… they are called elements

• But when chemical symbols combine, they are called......

Chemical Formulas

Chemical Formulas

• Chemical formulas represent different compounds (chemical substances)

• If chemical symbols are the “letters” of chemistry, then chemical formulas make up the “words”

• Examples in a jif

Chemical Formulas

H2O Fe2Cl HI CH4

C6H12O6 CaCO3 SF6

Chemical Formulas

Subscripts tell us how many atoms of the respective element that are present in that chemical substance

• H2O – The 2 tells us that there are 2 atoms of Hydrogen for every 1 atom of Oxygen present in water.

• If there is no subscript present, then it means that there is only one atom present in that substance

Methane

Methane has four Hydrogens

around one central Carbon

CH4

Criss – Cross Method of Formula Writing

Fe3+ + O2- Fe2O3

Fe O+3 -2

Fe2O3Criss-Cross will make ya JUMP JUMP!

Criss – Cross Method of Formula Writing

Na+1 + Br-1 NaBr

Na Br+1 -1

Na Br

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 covalently bonded with a single charge that bond ionically with other ions.Ex.

“ammonium sulfate” ,

NH4+1 SO4

-2

(NH4)2SO4

Criss – Cross Method of Formula Writing with Polyatomic

Ions

NH4+1 + O-2 (NH4)2O

NH4 O+1 -2

(NH4)2O

5) Polyvalent Metals:

Some metals including, but not limited to the transition metals do not follow the octet rule and may form more than 1 kind of cation. These ions are named with roman numerals to distinguish between them.Ex) Fe+2 iron (II) read “iron two”

Fe+3 iron (III) read “iron three” FeCl2 FeCl3 Copper (I) sulfate Copper (II) phosphate

Cu2SO4

Cu3(PO4)2

iron (II) chlorideiron (III) chloride

Naming Ionic Compounds

Binary Compounds

Rules for Naming Ionic Compounds

• For the Cation– Borrow the name of the element

• Ex. K+ is the “Potassium Ion”• Ex. Zn2+ is the “Zinc Ion”

– If an ion has more than one oxidation state• Cu+1 is “copper one ion”• Cu+2 is “copper two ion”

Rules for naming the anion

• Anion- the negatively charged atom– Use the name of the element followed by the

suffix “-ide”• Cl- is the Chloride ion• O-2 is the Oxide ion• P-3 is the Phosphide ion

Naming Ionic Compounds

• When naming ionic binary compounds:– Name the cation’s element name followed by

the anion’s name• NaCl is “Sodium Chloride”

• K2O is “Potassium Oxide”

• CuCl2 is “Copper (II) Chloride”

• Mg3N2 is “Magnesium Nitride”

• Al2S3 is “Aluminum Sulfide”

Naming Ionic Compounds with Polyatomics

• Name the Cation

• Name the Polyatomic ion

– Ex. Mg3(PO4)2

– “Magnesium Phosphate”

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

Bonding ObjectivesChem 5.0: Bonding, Formulas and Naming - OBJECTIVES

• Describe Ionic Bonding Theory.

• Describe Covalent Bonding Theory.

• Write formulas and names for ionic compounds including binary, tertiary and polyvalent.

• Write formulas and names for molecules (covalent compounds.)

• Write formulas and names for hydrates.

• Write formulas and names for binary and tertiary acids.

• Write Lewis-Dot structures for ionic compounds.

• Write structural formulas for covalent compounds.

• Describe electronegativity and how it affects bond type – ionic, polar covalent and nonpolar covalent.

6) Lewis Dot Diagrams for elements:

Element# of val. Electrons

Dot Diagram

Li Li

N

Be

F

Ne

Au

1

5

2

7

8

2

**Note: Only show s and p orbitals in dot diagram.

Electron Dot Diagram for Atoms and Ions

7) Lewis-dot diagram for sodium chloride:

[Na+] [ -]

Lewis-dot diagram for NaCl

Na Na+

-

Ionic Bond Formed

Na

[Na+] [ -]

Bonding ObjectivesChem 5.0: Bonding, Formulas and Naming - OBJECTIVES

• Describe Ionic Bonding Theory.

• Describe Covalent Bonding Theory.

• Write formulas and names for ionic compounds including binary, tertiary and polyvalent.

• Write formulas and names for molecules (covalent compounds.)

• Write formulas and names for hydrates.

• Write formulas and names for binary and tertiary acids.

• Write Lewis-Dot structures for ionic compounds.

• Write structural formulas for covalent compounds.

• Describe electronegativity and how it affects bond type – ionic, polar covalent and nonpolar covalent.

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

SF6 (Sulfur Hexafluoride)

Cool little video

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

Triple Bonds – Share 33 pairs of electrons (strongeststrongest bond).

Ex) ethyne

Bonding ObjectivesChem 5.0: Bonding, Formulas and Naming - OBJECTIVES

• Describe Ionic Bonding Theory.

• Describe Covalent Bonding Theory.

• Write formulas and names for ionic compounds including binary, tertiary and polyvalent.

• Write formulas and names for molecules (covalent compounds.)

• Write formulas and names for hydrates.

• Write formulas and names for binary and tertiary acids.

• Write Lewis-Dot structures for ionic compounds.

• Write structural formulas for covalent compounds.

• Describe electronegativity and how it affects bond type – ionic, polar covalent and nonpolar covalent.

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

Ionic or Covalent?

• Polar-covalent bonding- a covalent bond in which the bonded atoms have an unequal attraction for the shared electrons

In the fight for electrons, Igor wins (most of the time)

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

Ex) O2

Ionic or Covalent?

• Nonpolar covalent bonding- A covalent bond in which the bonding electrons are shared equally by the bonded atoms, resulting in a balanced distribution of electrical charge

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 uneven sharing electrons transferred

C. Ionic & Covalent Bonds Summary:

Ionic Bonding Covalent Bondingmetal-nonmetal

e- transferred

large electronegativity difference (>1.9)

ions formed

written cation (+) anion (-)

name cation - name anion

forms ionic compound (formula unit) in a crystal lattice

Written with a chemical or empirical formula

NaCl – sodium chloride

nonmetal-nonmetal

e- shared

electronegativity difference (0 1.9)

no ions

more electronegative element written last

use # prefixes/ends in ide

forms molecules

Written with a molecular or structural formula

CCl4 – carbon tetrachloride

carbon tetrachloride

Bonding ObjectivesChem 5.0: Bonding, Formulas and Naming - OBJECTIVES

• Describe Ionic Bonding Theory.

• Describe Covalent Bonding Theory.

• Write formulas and names for ionic compounds including binary, tertiary and polyvalent.

• Write formulas and names for molecules (covalent compounds.)

• Write formulas and names for hydrates.

• Write formulas and names for binary and tertiary acids.

• Write Lewis-Dot structures for ionic compounds.

• Write structural formulas for covalent compounds.

• Describe electronegativity and how it affects bond type – ionic, polar covalent and nonpolar covalent.

D. Acids:1) A molecular compound that

dissolves in water to produce HH 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 (vinegar)COOH acetic acid (vinegar)

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

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

H2SO4

H2SO3

sulfur or phosphor (to sound better) 2nd word is “acid”

If you “ate” something you don’t like, you say “ic”

sulfate sulfuric acid

sulfite sulfurous acid

HNO3 anion is nitrate nitric acid

root suffix

H3PO3 anion is phosphite

Nitrous acid, anion is formula is:

Phosphoric acid, anion is

formula is:

phosphorous acid

nitrite HNO2

phosphate

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 substance without water without water MgSOMgSO44

Ex) CuSO4 • 5H2O

CuSO4 – anhydrate (light blue/white)

copper (II) sulfate pentahydratecopper (II) sulfate pentahydrate (bright blue)