Periodic table, trends, ionisation energy

Describe the structure of the periodic table arrangement

• Increasing atomic number

• In periods showing repeating trends in physical and chemical properties

• In groups having similar chemical properties

First ionisation energy

Removal of 1 mol of electrons from 1 mol of gaseous atoms

Successive ionisation energies

Removal of 1 mol of electrons after the 1st ionisation energy

Explain the trend in ionisation energy down a group

• Atomic radius increases

• More inner shells - shielding increases

• Nuclear attraction to outermost electron decreases

• First ionisation energy decreases

Explain the trend in ionisation energy across a period

• Nuclear charge increases

• Same number of shells - similar shielding

• Atomic radius decreases

• Nuclear attraction to outermost electron decreases

• First ionisation energy increases

Metallic bonding

Strong electrostatic attraction between cations and delocalised electrons

Solid giant covalent lattices

Networks of atoms bonded by strong covalent bonds

Properties of giant covalent lattices

• High BP & MP due to strong covalent bonds

• Insoluble due to no interaction between strong covalent bonds and solvents

• Poor electrical conductors due to all electrons being involved in bonding, except for graphene and graphite

Why can graphene and graphite conduct electricity?

• There are available electrons for conductivity

Explain the variation in melting points across Period 2 & 3

• Trend in structure from giant metallic → giant covalent → simple molecular

• Decrease in melting points due to IMF’s weakening