C2 - Metals And Alloys

What is metallic bonding?

The strong electrostatic attraction between positive metal ions and a sea of delocalised electrons.

What is meant by delocalised electrons in metals?

Outer shell electrons that are not attached to any specific atom and can move freely through the whole structure.

What do we call the overall structure of metals?

A giant structure of atoms arranged in regular layers.

What do metal atoms become when they lose their outer electrons?

Positive metal ions.

Is metallic bonding the same as ionic bonding?

No, metallic bonding is different from ionic bonding.

Why do metals have high melting and boiling points?

Because a lot of energy is needed to break the strong metallic bonds.

Why are metals good conductors of electricity?

Because delocalised electrons can move and carry electrical charge.

Why are metals good conductors of heat?

Because delocalised electrons can move and transfer thermal energy.

Why can pure metals be bent and shaped?

Because the layers of atoms in metals can slide over each other.

Why are some pure metals (e.g. copper, gold, iron, aluminium) not hard enough for many uses?

Because their layers of atoms can easily slide over each other.

What is an alloy?

A mixture of metals (sometimes with small amounts of non-metals).

Why are alloys harder than pure metals?

The different sizes of atoms in alloys distort the layers, making it harder for them to slide over each other.

Summary of pure metals' properties

Good conductors of heat and electricity, high melting/boiling points, malleable (can be bent and shaped).

Summary of alloys' properties compared to pure metals

Alloys are harder and stronger because the layers cannot slide as easily.