CHEMICAL BONDING
Chemistry
Unit 6
EQ
How
do atoms make
compounds?
REVIEW- OXIDATION NUMBERS

Write the Lewis Dot Diagram and give the oxidation
number of the following.
S
O
Ca
Na
P
Al
BONDING



Chemical bond- hold two or more atoms held
together to make each have 8 valence electrons
Who they bond with is determined by their
oxidation number
Atoms gain, lose, or share electrons to get 8
valence electrons (Octet Rule)
IMPORTANT
Compounds are always neutral
 For ex-NaCl
 Na = oxidation #= 1+
Cl = oxidation # = 1Total charge on NaCl = 0= neutral
For ex- CaF2

Ca= oxidation # = 2+
F = oxidation # = 1F2 = 2Total charge = 0 = neutral
TYPES OF BONDS



Ionic- cation (metal) and anion (nonmetal) bond
based on oxidation number; metal loses electrons,
nonmetal gains electrons
Covalent- nonmetal and nonmetal share
electrons
Metallic- two metals share electrons
Oxidation
number
Tells about
The number of electrons
an atom has gained, lost
or shared
To become
STABLE
OXIDATION NUMBERS OF ELEMENTS CAN
BE FOUND BY GROUP #S ON THE
PERIODIC TABLE.
Group Number
Oxidation number
Group # 1
1+
Group # 2
2+
Group # 13
3+
Group # 14
4+
Group # 15
3-
Group # 16
2-
Group # 17 ( halogens)
1-
Group # 18 ( Noble Gases)
0
ONES AND TWOS




When do chemical bonds form?
Who is more reactive: alkali metals or alkaline
earth metals?
Give the number of valence electrons for oxygen,
sulfur, arsenic, phosphorous, and bromine.
Why does calcium form a +2 ion instead of a +3
ion?
Binary
Compound
Is a
compound
made up of 2
elements
For ex- NaCl is made up of 2
elements
Na
Cl
REVIEW- WRITE THE ANSWERS IN
YOUR NOTEBOOK

Which of the following compounds are Binary Compounds?
 KCl
 H2SO4
 CO2
 KI
 PO4
 P2 O 5
 CaSO4
TYPES OF BONDS
Purpose- to make atoms more stable
 How e are distributed determines the type of bond

Ionic- electrical attraction b/t cation & anions
 Covalent- sharing of e pairs b/t two atoms

VOCAB
Cations- positive ions
 Anions- negative ions

Electronegativity- the ability of an atom to
attract electrons; used to estimate if the bond is
ionic or covalent
 Diatomic- two of the same (the gases)

IONIC BONDING & IONIC
COMPOUNDS
Chap 8
BASICS OF IONIC BONDS

Bonding of metal + nonmetal


WS- Types of Chemical bonds
Transfer of electrons
Metal loses e- (cation) nonmetal gains e- (anion)
 Ionic charges cancel in the bonding


Formula unit- the smallest formula for an ionic
compound
Ex: table salt is composed of lots of atoms, but the formula is
written NaCl
 The ratio of ions in the formula unit depends upon the
oxidation numbers on the atoms

CHARACTERISTICS OF IONIC BONDS

Lattice energy- the energy required to form an ionic
compound (bond energy is specific to breaking a
bond)
Negative values indicate that energy is released
 Positive values indicate that energy is absorbed

PROPERTIES OF
IONIC VS. MOLECULAR COMPOUNDS






Ionic
*very strong bond b/c very
strong attractive force
High melting point (do not
vaporize at room temp)
High boiling point
Hard & brittle crystal
lattice: ordered repetition of
pos & neg charges
Good conductors (if they can
dissolve in water)
Made of metal & nonmetal
Molecular






*Strong bond, but weak
attractive force
Low melting point (most are
gaseous at room temp)
Low boiling point
Usually a gas at room temp,
soft solids, some liquids
Poor conductors
Made of nonmetals
POLYATOMIC IONS
 Polyatomic
Ion- a charged group of covalently
bonded atoms; covalently bonded, yet behaves
like an ion
 Pg 224 Table 8-6
SUMMARY

Answer the EQ- share your answer with the person
next to you AFTER you write (that means write
THEN talk)
MOLECULAR COMPOUNDS
Chap 9
Molecule- neutral group of atoms covalently bonded
together
 Molecular compound- many molecules bonded
together


Electrons are shared b/t atoms in a covalent bond
so they all have 8 valence electrons

Lewis structures- demonstrate covalent bonding
Draw the elements symbol
 Draw the number of valence electrons

PRACTICE- LEWIS STRUCTURES

Pg 244 #1-5

Pg 247 #12
IONIC OR COVALENT?

If two of the same atom are bonded together, then it is
completely covalent
Nonpolar covalent- bonding e are shared equally; 0-5%
ionic character or 0-0.3 EN difference
 Polar covalent- uneven sharing of e; 5-50% ionic
character or 0.3-1.7 EN difference

NAMING MOLECULAR COMPOUNDS
(prefix)1st element + (prefix) root 2nd element
Ex. P2O5 diphosphorous pentoxide

# of Atoms
1
2
3
4
5
6
7
8
9
10
Prefix
mono
di
tri
tetra
penta
hexa
hepta
octa
nona
deca
IONIC OR COVALENT?


EN values < 1.7 is a covalent bond b/c the bond has
50% or less ionic characteristics
The bond is ionic if the EN difference is > 1.7
Anions attract eCations give away e-
PRACTICE

Pg 249 # 13-17
COMPARE AND CONTRAST IONIC AND
COVALENT BONDS
Ionic bonds
__________
__________
___________
Covalent
bonds
________
________
_________
NAMING ACIDS

Oxyacids- contain hydrogen and an oxyanion (PI
with oxygen in it)
Replace –ate with –ic
 Replace –ite with –ous
 Ex. HNO3 nitrate  nitric acid


Binary Acids- contains H and one other element
Hydro + element + ic
 Ex. HCl = hydrochloric acid

PRACTICE- NAMING ACIDS

Pg 250 # 18-22
Know the symbols for partial negative charge on
the covalent bond (δ-) and partial positive charge
(δ+)
 Know how to tell the bond type based upon EN
values
