IGCSE Chemistry — Topic Index

Periodic Table — The First 20 Elements

Each page covers one element in depth with atomic data, chemical properties, key reactions, compounds, uses, and IGCSE exam tips.

#	Element	Symbol	Key Fact
1	Hydrogen	H	Lightest element, diatomic H₂
2	Helium	He	Noble gas, full outer shell
3	Lithium	Li	Alkali metal, Li-ion batteries
4	Beryllium	Be	Toxic, aerospace alloys
5	Boron	B	Metalloid, borosilicate glass
6	Carbon	C	Organic chemistry basis, allotropes
7	Nitrogen	N	78% of air, Haber Process
8	Oxygen	O	21% of air, supports combustion
9	Fluorine	F	Most reactive non-metal
10	Neon	Ne	Noble gas, neon signs
11	Sodium	Na	Alkali metal, yellow flame
12	Magnesium	Mg	Burns with white flame
13	Aluminium	Al	Most abundant metal, amphoteric
14	Silicon	Si	Metalloid, semiconductors
15	Phosphorus	P	White/red allotropes
16	Sulfur	S	Yellow solid, Contact Process
17	Chlorine	Cl	Halogen, bleaches litmus
18	Argon	Ar	Most abundant noble gas
19	Potassium	K	Lilac flame, very reactive
20	Calcium	Ca	Limestone cycle, brick-red flame