Transcript Nomenclature & Formula Writing Review

Nomenclature & Formula
Writing Review
Why do elements bond
together?

Elements react with each other so that they
may have a full outer shell of electrons.
 They will ‘share’ or ‘steal’ electrons from
each other in order to achieve this.
 Noble gasses already have full outer shell,
and this is why they do not tend to react
with other elements!
Simple Chemical Formulae

Each element has a combining capacity
which explains how many available
bonding spaces it has.
 This is linked to the number of valence
(outer orbital) electrons the element has.
 When 2 elements combine, every bonding
space must be used.
The criss-cross method:

Example: lithium and oxygen
What are the combining capacities?
Lithium: 1
Oxygen: 2
Because the “1” is implied, we simply write
the formula as Li2O.

When possible, the formula must be
reduced by its lowest common denominator.
Example: magnesium and oxygen
Try these!
1.
Sodium and bromine
NaBr
2.
Boron and oxygen
B2O3
3.
Calcium and iodine
CaI2
4.
Magnesium and sulphur
MgS
Nomenclature
(naming of molecules)
You should be familiar with four basic
naming rules from your previous years.
A. Metal-Nonmetal
Write the name of the metal first
2. The name of the nonmetal is written
second, with the ending of the name
changed to –ide
Example: Li2O
1.
Lithium oxide
B. Nonmetal-Nonmetal
1.
2.
3.
Write the names of the nonmetals in the
order that you find them (left to right) on
the periodic table.
Change the ending of the last one to –ide
Use prefixes to indicate how many of
each element is present
**The nonmetals are rebels! They do not always follow the criss-cross rule you
just reviewed. Fortunately, you can determine the formula from the name.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
MonoDiTriTetraPentaHexaHeptaOctaNonaDeca-
**generally not used for the first element
Example: P5Cl2
Pentaphosphorous dichloride
Your turn…
1.
CO
Carbon monoxide
2.
Si4O2
Tetrasilicon dioxide
3.
NI3
Nitrogen triiodide
C. Multivalent metals

These metals are found in the transition elements
area (middle of the periodic table)
 Some transition metals have more than one possible
combining capacity. For example, copper can have
a combining capacity of either 2 or 1.
 Roman numerals are used in the name to indicate
which ion is being used.
Example:
copper (I) chloride & copper (II) chloride
***You need to reverse this process to
convert from the formula to the name!
This is nickel (II) nitride.
Your turn again!
1.
Cobalt (II) selenide
CoS
2.
Tin (IV) bromide
SnBr4
3.
NiS
Nickel (II) sulphide
4.
Fe2O3
Iron (III) oxide
D. Polyatomic Ions

Your beloved data table contains a list of
common ions and their charges.
 For naming and formula purposes, treat the
ions as a single unit, and follow the crisscross rule as you have already been doing.
Hints:
You will be able to recognize polyatomic
names because they are the only ones
which do not end in –IDE!!
You will be able to recognize polyatomic
formulae because they are the only ones
with three or more elements.
(Of course, this will change as the year goes on….) 
Example: Calcium permanganate
Final round for you to try!!!

Sodium phosphate
Na3PO4

Strontium chlorate
Sr(ClO3)2

NH4Cl
Ammonium chloride

CaC2O4
Calcium oxalate