metallic bonding

properties of metals?(5)

are malleable

conduct electricity

are shiny

are ductile

good conductors of electricity

The electron sea model states that…

a metal is made up of a lattice of cations, surrounded by a ‘sea’ of delocalised electrons

Delocalised electrons allow metals to conduct electricity because they...

are charged and can move freely throughout the metal

Metallic bonding is defined as...

the attraction between cations and delocalised electrons

As the attraction between the cations and the sea of delocalised electrons increases, the strength of metallic bonding...

increases.

Metals are malleable and ductile because...

layers of cations can slide over each other without breaking the metallic bonding

Metals in the liquid state have what properties...(2)

conduct electricity

have metallic bonding

Metals in the gas state have which properties...

none of the properties of metals

just contain metal atoms

boiling and melting point of metals with stronger metallic bonding…

higher melting points

higher boiling points

Chemists say that metals have high melting and boiling points because...

there is a strong attraction between cations and delocalised electrons

f we look at the melting points of sodium, magnesium and aluminium we can see that they increase as we move across the period.

This implies that the strength of metallic bonding...

increases across a period

Across a period, the melting points of metals increase

And that’s because…

they form lattices with more highly charged cations

they delocalise more electrons per cation

Trend of melting point of metals down a group?

decreases

Down a group the melting point of metals decreases, and that’s because...

the distance between cations and delocalised electrons increases

alloys

Metals made from two or more elements

pure metals

Metals made from only one element

Predict which has a higher melting point

Sodium

Potassium

sodium

Potassium’s cation is larger than sodium’s cation

Potassium has weaker metallic bonding than sodium

State and explain the trend in melting point down the Group 2 metals.

Down Group 2 the size of the cation increases.

This means down Group 2 the distance between cations and delocalised electrons increases.

This increased distance means the strength of metallic bonding decreases down Group 2 which, in turn, means melting point decreases down a group.