Download Slide 1

Writing Formulas and Naming Compounds
Atoms and molecules react with one
another to become more stable. Atoms
become more stable by either
gaining/losing electrons so that they have 8
valence electrons (full outer energy level).
Na 1s2 2s2 2p6 3s1
Cl
1 valence electron
1s2 2s2 2p6 3s2 3p5 7 valence electrons
Sodium will lose 1 e- to get 8 valence
electrons (a noble gas configuration).
Chlorine will gain 1e- to get 8 valence e- (a
noble gas configuration).
Na  Na+1 + 1e-
Cl + 1e-  Cl-1
Na+1 + Cl-1  NaCl
The Na+1 and Cl-1 ions have very different
properties than the Na and Cl atoms.
Atoms form ions by gaining or losing
electrons. The metals tend to lose electrons
(positive ions), the nonmetals tend to gain
electrons (negative ions).
The position of the element on the periodic
table can help determine how many valence
electrons the atom has, and what charge it
will probably have when it becomes an ion.
Groups and Ion Charges
Group
1
2
13
14
15
16
17
18
Valence e1
2
3
4
5
6
7
8
Gain/Lose eLose 1
Lose 2
Lose 3
Tweener
Gain 3
Gain 2
Gain 1
0
Ion charge
+1
+2
+3
+4/-4
-3
-2
-1
0
Ions are atoms with different numbers of
protons and electrons. They are formed by
either gaining or losing electrons.
If an atom loses electrons, it has more
protons than electrons and becomes
positively charged. This is called a cation,
and usually happens to the metals.
If an atom gains electrons, it has more
electrons than electrons and becomes
negatively charged. This is called an anion,
and usually happens to the nonmetals.
Monatomic Ions – an ion made up of only one
type of atom (H+1, Ca+2, S-2, Cl-1, …)
Polyatomic Ions – an ion made up of two or
more different types of atoms (NO3-1, OH-1,
SO4-2, NH4+1, …)
The compound Na3PO4 is made up of 3
monatomic ions (Na+1) and 1 polyatomic ion
(PO4-3).
Ions are named differently than elements
because they have different properties. In
General
•Metals – the word ion is added after the
name of the element.
Na = sodium
Na+1 = sodium ion
•Nonmetals – the ending of the element is
dropped, and –ide is added.
Br = bromine
Br-1 = bromide
O = oxygen
O-2 = oxide
Ionic compounds are made from ions
combining. The compound has no net charge,
or is neutral, even though it is made up of
both positive and negative ions.
Naming compounds and writing formulas is
easy if you know the names, charges and
formulas of all of the ions on the ion list. If
you don’t know these, you will be guessing on
all of your names or formulas.
Polyatomic Ions
Formula
NH4+1
NO3-1
ClO3-1
OH-1
C2H3O2-1
SO4-2
CO3-2
PO4-3
Name
Ammonium
Nitrate
Chlorate
Hydroxide
Acetate
Sulfate
Carbonate
Phosphate
Elements with more than one
charge
Name
Symbol
Name
Symbol
Copper (I)
Cu+1
Copper (II)
Cu+2
Chromium (II)
Cr+2
Chromium (III)
Cr+3
Manganese (II) Mn+2 Manganese (III) Mn+3
Cobalt (II)
Co+2
Cobalt (III)
Co+3
Iron (II)
Fe+2
Iron (III)
Fe+3
Nickel (II)
Ni+2
Nickel (III)
Ni+3
Tin (II)
Sn+2
Tin (IV)
Sn+4
Lead (II)
Pb+2
Lead (IV)
Pb+4
Naming Ionic Compounds
Give the name of the positive ion, cation,
including the roman numeral if appropriate
followed by the name of the negative ion,
anion.
•Names of the cation are the same as the
name of the element.
•Names of monatomic anions usually end
with -ide.
•Names of polyatomic anions usually end
with –ate.
NaCl
sodium chloride
LiNO3
lithium nitrate
CuCl
copper (I) chloride
CuCl2
copper (II) chloride
Sr(ClO3)2
strontium chlorate
MgO
magnesium oxide
CaSO4
calcium sulfate
FeBr3
iron (III) bromide
Writing correct ionic formulas
Write the cation followed by the anion
 Cross the numerical charges to become
the subscripts. Drop all +/- signs
 If the subscripts are 1, do not write the 1. If
the subscripts are multiples, reduce them.
 If more than one polyatomic ion is needed,
put ( ) around the polyatomic ion before
adding the subscript.

Ionic Compounds
•Made up of positive and negative ions
•Made up of metals and nonmetals
•“Salts”
•Will conduct electricity when dissolved in
water
•Electrons are transferred between atoms
•Opposites attract
•Positive ion always comes first
Covalent Compounds
•Made up of two or more nonmetals
•Electrons are shared between atoms
•Do not conduct electricity in water
•No ions are present
Prefixes
Prefix
Meaning
Prefix
Meaning
Mono-
1
Hexa-
6
Di-
2
Hepta-
7
Tri-
3
Octa-
8
Tetra-
4
Nona-
9
Penta-
5
Deca-
10
Naming covalent compounds
Give the prefix telling how many of the first
element (except mono-), then give the
name of the first element.
 Give the prefix telling how many of the
second element, then give the name of the
second element ending with –ide.
 P2O5
CO
CO2
N 2O4
PCl3
ICl3
SiO2
N4Cl7

Naming Acids: HX, H2X, H3X
If the anion X ends in –ide
 hydro (name of anion, drop the ending) –ic acid
HCl hydro chloric acid HBr hydrobromic acid
H2O hydro oxic acid
H2S hydro sulfuric acid

If the anion X ends in –ate
 (name of the anion, drop the ending)-ic acid
HNO3
nitric acid
H2SO4
sulfuric acid
HClO3
chloric acid HC2H3O2 acetic acid

Names and formulas of common
acids
H2SO4
 HCl
 HNO3
 HC2H3O2
 H3PO4

Sulfuric Acid
 Hydro chloric acid
 Nitric acid
 Acetic acid
 Phosphoric Acid
