3.3 Metallic bonding

Question 1

Describe the structure of metal elements

Answer 1

Giant metallic lattice structures

The outer shell of electrons of a metal atom is delocalised (can move about the atom and aren’t tied to a particular one)

Positive metal ions are attracted to the negative delocalised electrons so there is electrostatic attraction between them.
This balances the repulsion between positive ions.

Question 2

Why does metallic bonding happen,

Answer 2

. The atoms in a metal can’t transfer electrons (as happens in ionic bonding) unless there is a non metal element present to recieve them.

So in metallic bonding, the outer main levels of atoms merge and the outer electrons become delocalised as they don’t associate with any one particular atom

Question 3

what do the number of delocalised electrons depend on

Answer 3

. Depend on how many electrons have been lost by each metal atom.

Question 4

Why are metals good conductors of electricity

Answer 4

. The delocalised electrons can move throughout the structure and so carry charge throughout it.

. Eg an electron from the negative terminal of the supply joins the sea of delocalised electrons at one end of the metal wire

. Meanwhile a different electron leaves the wire at the positive terminal

Question 5

Why are metals good conductors of heat

Answer 5

. They have high thermal conductivities

. The sea of delocalised electrons is partly responsible for this property as they can move around the metal, colliding with metal atoms to transfer heat

. Also their particles are very closely packed so energy is also spread by increasingly vigorous, vibrations of the closely packed ions.

Question 6

What does the strength of metallic bonding depend on in metals

Answer 6

. Strength of metallic bond depends on:

• The charge of the ion: the greater the charge, the greater the number of delocalised electrons and the stronger the electrostatic forces of attraction between positive ions and electrons
• The size of the ion- the smaller the ion, the closer the electrons are to the positive nucleus, so the stronger the bond.

Question 7

Why are metals strong

Answer 7

Delocalised electrons can extend throughout the solid so there are no individual bonds to break.

It involves the sharing of outer electrons between metal atoms which creates strong electrostatic forces of attraction between the positive ions and the negative delocalised electrons

Question 8

Why are metals malleable and ductile

Answer 8

. Metals are melleable (can be beaten into shape)
. And ductile (can be pulled into thin wires)

This is because there are no bonds holding specific ions together, so the ions can slide over each other when the structure is pulled

Question 9

Describe the melting point of metals

Answer 9

.High melting and boiling points because of strong electrostatic forces of attraction between positive metal ions and delocalised electrons.

. Metals are usually giant structures so there are lots of delocalised electrons (the more there are, the stronger the bonding will be so the higher the melting point)

Eg Mg2+ has two delocalised electron per atom, so it will have a higher melting point than Na+.

Question 10

Describe the solubility of metals

Answer 10

. Insoluble, except for liquid metals because of the strength of metallic bonds