Transcript Ca = +2, Cl = -1

IONIC BONDING
An electrical attraction between two
oppositely charged atoms or groups of
atoms.
Happens when an atom of a nonmetal
takes one or more electrons
from an atom of a metal
so both atoms end up with
eight valence electrons
The Octet Rule
• The octet rule says
that atoms can
become stable by
having eight electrons
in their outer energy
level, as shown in the
noble gas, Neon, (or
two electrons in the
case of some of the
smallest atoms).
Electron Dots For Cations
Metals will have few valence electrons
 These will come off

Ca
Electron Dots For Cations
Metals will have few valence electrons
 These will come off
 Forming positive ions

2+
Ca
Electron Dots For Anions
Nonmetals will have many valence
electrons.
 They will gain electrons to fill outer shell.

P
3P
IONIC COMPOUNDS
metal with nonmetal
+ ion
- ion
Ca+ion
anion
Predicting Oxidation
Number or Charge from
Periodic Table
Forming Cations
metals
group 1A
group 2A
group 3A
group 4A
lose elose 1
lose 2
lose 3
lose 4
form cations
+1 charge
+2 charge
+3 charge
+4 charge
oxidation #
1+
2+
3+
4+
Forming Anions
Non-metals
gain e-
group 7A
group 6A
group 5A
gain 1
gain 2
gain 3
form anions
-1 charge
-2 charge
-3 charge
oxidation #
123-
+1
1
H
2
Li
3
4
5
6
7
11
0
+2
+3
+4
-3
-2
-1
Be
B
C
N
O
F
12
Na Mg
13
+3
19
20
21
22
23
24
K
Ca Sc
Ti
V
Cr Mn Fe Co Ni
37
38
39
Rb Sr
Y
55
56
71
40
76
45
77
Cs Ba La Hf Ta W Re Os Ir
87
88
103 104
Fr
Ra Ac Rf
105
106
107
108
109
46
17
18
Si
P
S
Cl
Ar
Cu Zn Ga Ge As Se Br
Kr
29
30
+2
Al
31
32
35
36
48
+2
49
79
80
81
82
83
84
Pt Au Hg Ti
Pb
Bi
Po At Rn
Db Sg Bh Hs Mt
Oxidation Numbers
51
34
47
+1
78
50
33
I
75
44
28
16
Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te
74
43
27
15
53
73
42
26
N
14
52
72
41
25
He
85
54
Xe
86
IONIC BONDING
Neutral atoms come near
each other.
Electron(s) are transferred
from the Metal atom to the
Non-metal atom.
They stick together because
of electrostatic forces, like
magnets.
Steps for writing ionic bond formulas
1. Determine the oxidation numbers for the two
elements or ions.
Ca = +2, Cl = -1
Steps for writing ionic bond formulas
2. Write the chemical symbols in the correct
order, with the metal ion first and write the
oxidation numbers as superscripts.
Ca 2+ Cl -1
Steps for writing ionic bond formulas
3. Crisscross the numbers only—not the
charge signs—writing the oxidation
number of one element as a subscript for
the other. Don’t write number 1 either.
Ca 2+ Cl 1Ca 1 Cl 2
Ca Cl2
Steps for writing ionic bond formulas
4. Determine
whether the formula is in its
simplest form. Reduce the subscripts to the
simplest from by dividing by a common
denominator.
Ca+2
O-2
Ca2
O2
CaO
= Ca2O2
Steps for writing ionic bond formulas
5. Check the formula by calculating the total
positive and negative charges and confirming
that the total charge on the compound is zero.
CaCl 2
Oxidation Number
Subscript
Calcium
(+2)
x
(1)
=
+2
Chlorine
(-)
x
(2)
=
-2
Practice these!

magnesium and oxygen

aluminum and bromine

sodium and sulfur

potassium and nitrogen
MgO
AlBr3
Na2S
K3N
More Practice!
potassium bromide
 calcium oxide
 Silver fluoride

KBr
CaO
AgF
Polyatomic ions

Groups of atoms that stick together as a
unit, and have a charge
 PO43-
phosphate
 CO32- carbonate
 C2H3O41- acetate

Names often end in –ate or –ite
Steps for writing ionic bond formulas
6. POLYATOMIC IONS ACT JUST LIKE ANY
OTHER NEGATIVE ION WHEN BONDING
Treat polyatomic ion as single unit—
don’t change it in any way!
Steps for writing ionic bond formulas
Steps for writing ionic bond formulas
polyatomic ions are enclosed in
parenthesis if taken more than once in
the formula.
A subscript outside the parenthesis
multiplies everything inside.
Steps for writing ionic bond formulas
Practice

potassium hydroxide
KOH

zinc (II) carbonate
ZnCO3

barium chlorate
Ba(ClO3)2
aluminum phosphate
AlPO4

More Practice

calcium acetate
Ca(C2H3O2) 2

sodium nitrate
NaNO3

aluminum hydroxide
Al(OH) 3
ammonium phosphate
(NH4)3 PO4

Naming Ionic Compounds
1. name cation - then anion
2. if anion (nonmetal) is a single element
….. then name ends in “-ide”
Naming Ionic Compounds
3. If metal have more than one possible
charge (include roman numeral in
parenthesis to give charge)*
*All metals except:
Ag+1, Zn+2, Cd+2, Al+3
Practice (no transitional metals)

Na2O
Sodium oxide

Mg(OH)2
Manganese (II) oxide

Al(NO3)3
Aluminum nitrate

NH4Cl
Ammonium chloride
Practice with transitional metals
Hint: look at the subscript in the anion
to predict the metal oxidation number.

Sn(ClO3)4
Tin(IV) chlorate

Cu2CO3
Copper (I) carbonate

Fe2O3
Iron (III) oxide

NiSO4
Nickel (II) sulfate
Properties of Ionic Compounds
Crystalline structure.
 A regular repeating arrangement of ions in
the solid.
 Ions are strongly bonded.
 Structure is rigid.
 High melting points- because of strong
forces between ions.

Crystalline structure
The repeating unit is called the unit cell
3 dimension
Crystalline structure
The POSITIVE
CATIONS
stick to the
NEGATIVE
ANIONS, like
a magnet.
+
+
- - +
+ + - + - +
- + - +
Ionic solids are brittle
+
+
-
+
+
+
+
-
+
+
Ionic solids are brittle

Strong Repulsion breaks crystal apart.
- + - +
+ - + - + - +
Cubic
Body-Centered Cubic
Face-Centered Cubic
Do they Conduct?







Conducting electricity is allowing charges to
move.
In a solid, the ions are locked in place.
Ionic solids are insulators.
When melted, the ions can move around.
Melted ionic compounds conduct.
First get them to 800ºC.
Dissolved in water they conduct.