- Between a non-metal and a metal
- The metal loses electrons to form a positive ion. The non-metal gains electrons to become a negative ion.
- They are in the shape of a giant lattice.
- Held together by strong electrostatic forces of attraction.
- They have high melting and boiling points because a lot of energy is needed to break the strong forces of attraction.
- Solid ionic compounds do not conduct electricty but they do if melted or are added to water.
- Atoms of two non-metals combine.
- They share electrons to reach a stable structure (like noble gases(group 7)).
- Covalent bonds are very strong between atoms within a molecule.
- But weak intermolecular forces in simple molecules mean low melting and boiling points. (simple molecules have little attraction for each other).
- They are poor conductors of electricity.
- Have strong structures so melting and boiling points are high.
Substance: Diamond(Carbon) Hardness:Very hard ( Hardest natural substance)
Substance: Graphite(Carbon) Hardness: Soft (used as lubricant)
Substance: Silicon dioxide(Sand) Hardness: Very hard
On the next three cards are diagrams of the structures of all three of the above--------------->
Diagram of the structure of diamond
Diagram of the structure of graphite
Graphite is arranged in layers.
Diagram of the structure of silicon dioxide
Bonding in metals
- Atoms in a metallic element are all the same size.
- Form giant structures in which layers of atoms are arraged in regular patterns.
- Held together by electrostatic forces.
- When metal atoms pack together the electrons in the highest energy level (outer shell electrons) delocalise and move from one atom to another. These electrons attract the positive ions and hold the structure together.
- Can conduct both heat and eletricity because of the free moving electrons.