Chemistry:AS Chemistry

AS Chemistry

GETTING HELP WITH CHEMICAL FORMULAE

Translating words into symbols:
You must know the chemical symbols for all the elements that you will meet in your A level course. The following is a list of the most common ones, but be prepared to learn others as you meet new topics!

Argon	Ar	Aluminium	Al	Antimony	Sb
Boron	B	Barium	Ba	Beryllium	Be
Carbon	C	Calcium	Ca	Copper	Cu
Cobalt	Co	Chlorine	Cl	Chromium	Cr
Fluorine	F	Gold	Au	Hydrogen	H
Helium	He	Iodine	I	Krypton	Kr
Lithium	Li	Magnesium	Mg	Manganese	Mn
Mercury	Hg	Neon	Ne	Nitrogen	N
Nickel	Ni	Oxygen	O	Phosphorus	P
Platinum	Pt	Rubidium	Rb	Silicon	Si
Sulphur	S	Sodium	Na	Silver	Ag
Tin	Sn	Titanium	Ti	Uranium	U
Vanadium	Vn	Xenon	Xe	Zinc	Zn

When you write the symbol for the element it represents one atom of that element.

Formulae of the common gases:

The noble or inert gases only exist as single atoms and can be written as:

one atom of neon - Ne

one atom of argon - Ar

If several atoms are present a large number is written in front of the symbol:

3 atoms of helium - 3He

4 atoms of neon - 4Ne

It is helpful to realise that many common gases exist as diatomic molecules and not as single atoms: This means they consist of two atoms covalently linked together:

They are shown as:

oxygen O₂
nitrogen N₂
chlorine Cl₂
bromine Br₂
hydrogen H₂
fluorine F₂

A well known exception is ozone which is O₃!