GCSE Science | Periodic Table

Group Number

• the columns (1, 2, 3, ... 8)
• the number of electrons in the outer shell
• elements in the same group have similar chemical properties

Why do things react?

• elements want to gain a full or an empty outer shell

Group 8

• noble gases
• they already have a full outer shell
• very unreactive

Ions

• Ions are formed when an atom
• gains or loses electrons

Examples of ions

• group 1 elements try to lose 1 electron
• forming 1+ ions
• group 7 elements try to gain one electron
• forming 1- ions

How does reactivity change as you go down group 1? (3 marks)

• reactivity increases as you go down group 1
• easier to lose an electron
• outer shell further away from the nucleus
• more electron shielding
• less nuclear attraction

How does reactivity change as you go down group 7? (3 marks)

• reactivity decreases as you go down group 1
• harder to gain an electron
• outer shell further away from the nucleus
• more electron shielding
• less nuclear attraction