Ionic Compounds
Atoms vs. Ions
Ion: an atom that has lost or gained electrons
Ions have a charge because the # of protons
does NOT equal the # of electrons
Ions
How do you know if an atom will lose or gain
electrons?
Less than 4 valence electrons = lose
More than 4 valence electrons = gain
Ions
cation: positive ion
anion: negative ion
Lewis Dot Diagram
Se
Ionic Bonding
Electrons are transferred from one atom to
another so that each has 8 valence electrons
- called the octet rule
+
Cation
Anion
Ionic Compound
Ionic bond: bond formed by attraction
between + and - ions
Ionic Bonding
Ionic bonds occur between metals and non-metals
H
He
Li
Be
B
C
N
O
F
Ne
Na
Mg
Al
Si
P
S
Cl
Ar
K
Ca
Sc
Ti
V
Cr
Mn
Fe
Co
Ni
Cu
Zn
Ga
Ge
As
Se
Br
Kr
Rb
Sr
Y
Zr
Nb
Mo
Tc
Ru
Rh
Pd
Ag
Cd
In
Sn
Sb
Te
I
Xe
Cs
Ba
Lu
Hf
Ta
W
Re
Os
Ir
Pt
Au
Hg
Tl
Pb
Bi
Po
At
Rn
Fr
Ra
Lr
Rf
Db
Sg
Bh
Hs
Mt
Uun
Uuu
Uub
Uut
+
Cation
Metals
Metalloids
Non-metals
Anion
Binary Ionic Compounds
Formula to Name
Binary Ionic Compounds
Formula to Name
• Formula will have…
– only 2 elements
– a metal and a non-metal
• To name:
Metal name + nonmetal name ending in –ide
The subscripts in the formula do not matter when
naming this type
Examples
CaBr2
K2O
Write the
name for the
following
compounds
Practice
1. CaF2
calcium fluoride
2. Na3P
sodium phosphide
3. NaI
sodium iodide
4. SrBr2
strontium bromide
Binary Ionic Compounds
Name to Formula
Example
The “magic number” is 8!
Binary Ionic Compounds
Name to Formula
• Names will…
– end in “-ide” (except “hydroxide and cyanide”)
– NOT contain covalent prefixes
• To write the formula:
1. Draw Lewis dot diagrams of each element and transfer
electrons to complete the octet.
2. Use subscripts to show how many of each type of ion you
have.
Example
Rubidium sulfide
Write the
formula for
the following
compounds
Practice
1. cesium chloride
CsCl
2. potassium oxide
K2O
3. calcium sulfide
CaS
4. lithium nitride
Li3N
Multivalent Ionic Compounds
Name to Formula
Multivalent (Transition) Metals
Multivalent Metal: a metal that can form more
than one ion (has more than one + charge)
Examples:
Cobalt
Copper
Iron
Lead
Manganese
Mercury
Tin
Co+2
Cu+1
Fe+2
Pb+2
Mn+2
Hg2+2
Sn+2
Co+3
Cu+2
Fe+3
Pb+4
Mn+3
Hg+2
Sn+4
Multivalent Ionic Compounds
Name to Formula
• Names will…
– have roman numerals (I, II, III, IV, etc.)
• To write the formula:
– Same as binary, except Roman numerals tell the
charge of the metal cation
Examples
Iron (III) oxide
Copper (I) nitride
Write the
formula for
the following
compounds
Practice
1. Iron (II) nitride
Fe3N2
2. Copper (I) chloride
CuCl
3. Lead (IV) sulfide
PbS2
4. Tin (II) oxide
SnO
Multivalent Ionic Compounds
Formula to Name
Multivalent Ionic Compounds
Formula to Name
• Formula will have…
– a transition metal
• To name:
Metal name + (charge in Roman numerals) +
nonmetal name ending in -ide
•
To determine the metal charge, make a list!
1. List each nonmetal ion with the charge
2. Total negative charge = total positive charge
3. Divide the total positive charge between the metal atoms
4. Write the charge of one atom in roman numerals in
parenthesis after the metal’s name
Examples
CuCl2
Fe2O3
Write the
name for the
following
compounds
Practice
1. PbCl2
Lead (II) chloride
2. SnBr4
Tin (IV) bromide
3. MnO
Manganese (II) oxide
Polyatomic Ionic Compounds
Polyatomic Ionic Compounds
Polyatomic Ion: a group of atoms that has
lost or gained electrons – so it has a charge!
Polyatomic Ionic Compound: compound
containing at least one polyatomic ion
+
Cation
Polyatomic
Anion
Polyatomic Ionic
Compound
Identifying Polyatomic Ions
• Only one cation: NH4+
• All others are anions (second part of formula)
• Subscripts must match exactly as it appears on
the list on your periodic table
Practice Identifying Polyatomic
Ions
Identify and
name the
polyatomic ion
in each
compound
1. NaNO3
2. NH4Cl
3. Ca(OH)2
4. (NH4)3PO4
5. K2CO3
Practice Identifying Polyatomic
Ions
Identify and
name the
polyatomic ion
in each
compound
NaNO3
Nitrate
NH4Cl
Ammonium
Ca(OH)2
Hydroxide
(NH4)3PO4
Ammonium &
phosphate
K2CO3
Carbonate
Polyatomic Ionic Compounds
Formula to Name
Polyatomic Ionic Compounds
Formula to Name
• Formula will have…
– MORE than 2 capital letters
– at least one metal and one non-metal
• To name:
Metal name + nonmetal polyatomic ion name
• write the polyatomic ion’s name exactly as it
appears on your periodic table
Examples
NaNO3
Fe(OH)
2
Write the
name for the
following
compounds
Practice
1. Ca(NO3)2
2. Na3PO4
3. NH4ClO
4. K2CO3
Polyatomic Ionic Compounds
Name to Formula
Polyatomic Ionic Compounds
Name to Formula
•
•
Names will…
– end in –ite or –ate (except for hydroxide)
– Do not use covalent prefixes
To write the formula:
• Make a list!
1. Write the symbol and charge of the cation and anion
2. Add additional cations or anions until the charges
cancel out to zero
3. Use subscripts to show the number of each ion
When using subscripts with a polyatomic ion, you must
put the polyatomic ion in parenthesis.
Examples
Sodium carbonate
Magnesium nitrate
Write the
formula for
the following
compounds
Practice
1. Sodium nitrate
NaNO3
2. Calcium chlorate
Ca(ClO3)2
3. Potassium sulfite
K2SO3
4. Calcium hydroxide Ca(OH)2
Example
Anion
Fe2O3
Total
Total
negative
positive
charge in
charge in
compound compound
Cation
Name