CHEMICAL BONDING

Chemical Bonds / Formulas

Atoms bond to become “happy” – octet rule

When they bond they form compounds.

Each compound has a special formula

Subscripts show how many of each element is in the compound

FORMULASMgCl2

The subscript is the number at the bottom of a formula.

There is 1- Mg & 2 – Cl Never use 1 as a subscript!

IONIC BONDformed between two ions by the transfer of electrons

Formation of Ions from Metals

Ionic compounds result when metals react with nonmetals

Metals lose electrons to form a positive charge

Nonmetals gain electrons to form a negative

charge

Metals: Nonmetals:

Na+ N -3

Ca+2 S -2

Al+2 Br -

IONIC BONDS Bonds form from the (+) & (-)

charges. Form a network of ions. Form

strong bonds. Conduct electricity when

melted or dissolved in water.

Writing Ionic Formulas – binary

Calcium & oxygen

Write the metal ion Ca +2

Write the nonmetal ion O -2

If charges cancel – ratio is 1:1 ( 1 of each)

CaO

Magnesium & chlorine

Write the metal ion Mg +2

Write the nonmetal ion Cl -

If charges DO NOT cancel – drop & swap

MgCl2

Transition Metals – d & f block Ion charges change – an element can have

more than one ion charge

The charge is given as a ROMAN NUMERALEx: Iron (II) Fe+2 / Iron (III) Fe+3

Gold (I) Au + / Gold (III) Au+3

You will not have to memorize all the charges each transition metal forms – the charges will be given to you !!!!!

Practice

Magnesium & iodine

Iron (III) & bromine

Barium & nitrogen

Aluminum & phosphorus

Naming Ionic Formula - binary

Representative MetalsName the metalChange the ending of

the nonmetal to – ide

Ex:MgCl2 - magnesium chloride

AlP - aluminum phosphide

Transition MetalsName the metal & Include the

charge using a Roman Numeral

Change the ending of the nonmetal ending to –ide

Ex:

Fe +2 Cl - iron (II) chloride

Au + O -2 gold (I) oxide

Practice CaBr2

Na3N

BCl3

MgO

FeCl3

Ni3N

ZnO

FeS

Ternary Ionic Bonds – contain Polyatomic Ions

Polyatomic ion : a group of (covalently) bonded nonmetals that form a charge.

Act as a single ion in an ionic bond

Have special names that DO NOT CHANGE

You need to write down the polyatomic ions and their names on an index card and DO NOT LOSE IT!!!

You will use your list on all quizzes and tests!

AmmoniumNH4+

Acetate C2H3O2-

Hypochlorite ClO-

Chlorite ClO2-

Chlorate ClO3-

PerchlorateClO4-

Cyanide CN-

Hydroxide OH-

Nitrite NO2-

Nitrate NO3-

Bicarbonate/Hydrogen Carbonate HCO3-

Carbonate CO3-2

Chromate CrO4-2

Dichromate Cr2O7-2

Oxalate C2O4-2

Sulfate SO4-2

Sulfite SO3-2

Phosphite PO3-3

Phosphate PO4-3

Permanganate MnO4-

Peroxide O2-2

Writing Ionic Formulas - ternary Write the cation – all metals (only polyatomic cation is

ammonium: NH4+ )

Write the anion – all nonmetals and polyatomic ions

If charges cancel – 1:1 ratio

If charges DO NOT cancel – drop & swap You must use parenthesis if more than one polyatomic

ion is present

Naming Ionic Formulas- ternary Cation

Representative metals- element nameTransition (D-block) metals- element name and a

Roman numeral to show chargePolyatomic ion (NH4

+)- regular name

AnionPolyatomic ion- regular nameNonmetal- change ending to -ide

Ex:NaNO3- sodium nitrate

Cu2(SO4)3- copper (III) sulfate

NH4Cl- ammonium chloride

Practice cesium nitrate

barium sulfite

aluminum hydroxide

strontium phosphate

ammonium sulfide

Iron(III) chlorite

Zinc(II) nitrite

Gold(III) carbonate

Silver(I) phosphite

Copper(I) acetate

COVALENT BONDbond formed by the sharing of electrons

Covalent Compounds

Covalent compounds result when nonmetals bond with nonmetals

Both nonmetals share their valence

electrons to be happy – Octet Rule

Examples:

CO2 SCl2

H2O CH4

Naming Covalent formulas Use prefixes to show the # of atoms of each

element in a covalent compound 1 – mono 6 - hexa 2 – di 7 - hepta 3 – tri 8- octa 4 – tetra 9 - nona 5 – penta 10 – deca

1st element – use prefixes only of the # of atoms is greater than 1

2nd element – use prefixes; change ending to – ide

Practice

CO2

N3F8

Se4Br9

S7O

tetraselenium nonabromide

trinitrogen octafluoride

heptasulfur monoxide

carbon dioxide

Writing Covalent formulas Use the prefix to identify how many of each

nonmetal atoms are in each molecule The prefix becomes the subscript.

Carbon Tetrahydride Disulfur Hexachloride○ CH4 S2Cl6

1) Name the following covalent compounds:a) SiF4

b) N2S3

c) H3Br7

d) S5Br9

e) H2O

2) Write the formulas for the following covalent compounds:

a) diboron hexahydrideb) nitrogen tribromidec) sulfur hexachlorided) diphosphorus pentoxide

Drawing Structures- Ionic Electrons are

TRANSFERRED

Practice: NaBr

AlCl3

Drawing Structures- Covalent Electrons are SHARED

1 pair= single bond2 pairs= double bond3 pairs= triple bond

Dot formulas and Structural formulas

Covalent Structure Practice H2O CH4

CO2 Cl2

O2 N2

Diatomic Molecules

Always pair up with themselves in a pure sample

Allows them to be stable when there are no other elements to bond with

H2, N2, O2, F2, Cl2, Br2, I2

Metallic Bonds Formed between two metals

One or two valence electrons (usually transition metals)

strong positive nuclei pull atoms close together, causing the outer e- orbitals to overlap

electrons delocalize; creates a ‘sea of electrons’○ electrons flow freely between atoms, this is why metals

are good conductors of electricity

The remaining slides are for

HONORS CHEMISTRY

only

VSEPR

Valence Shell Electron Pair RepulsionPredicts shapes of

covalently bonded molecules

Copy the chart on p.263 of your book

Coordinate Covalent Bonds one atom contributes both bonding

electrons once formed, no different from other

bonds, just different source of electrons

Coordinate Covalent Ex:Chlorate, ClO3

-

Resonance Structures

shifting of electron pairs/bonds without shifting atoms

Resonance Ex:Carbonate, CO3

-2

Ozone, O3