OCR A-Level Chemistry A 3.1.1-3.1.4 Definitions

-The periodic table -Ionisation energies -Periodic trends in bonding and structure -Group 2 -The halogens -Qualitative analysis

Period

A row of elements with their highest energy electron in the same shell

Group

A column of elements with similar chemical and physical properties and with the same number of electrons in their outer shell

Periodicity

The repeating trend in properties across each period in the periodic table

First ionisation energy

The energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of 1+ ions

Reducing agent

A substance that adds electrons to other species and loses electrons itself

Oxidation agent

A substance that removes electrons from other species and gains electrons itself

Disproportionation

The simultaneous oxidation and reduction of the same element