Bonds

• There are strong covalent bonds between the atoms but weak forces between individual molecules.
• They have low boiling and melting points.
• They are liquids are gases at room temperatures or solids but with low melting points. 
• No charged particles so don't conduct electricity. 

• The covalent bonds in giant molecular covalent substances are strong and so it takes a lot of energy to break these bonds and because of this they have very high melting points.
• They are very hard substances that do not conduct electricity as they have no free electrons. 

• High melting point
• Conducts electricity as fourth bond can move freely between layers as it is delocalised so electricity can pass through.
• Very soft - each atom is joined to three others. Layers are held by weak forces and can slide off.

• High melting and boiling points as the ions are held together by very strong electrostatic forces and so lots of energy is needed to break these bonds.
• Ionic substances are solid at room temperature and must be heated strongly to melt.
• They only conduct when they are molten or dissolved in water because the charged particles can move.

Diamond

• Diamond is used for cutting tools as it is very hard.

Graphite

• It is used as a lubricant because forces between layers are weak and layers can slide over each other.
• Graphite has one free electron from each carbon that can move along the layers so graphite conducts electricity and can be used to make electrodes.

Done to obatain nitrogen and oxygen.

• Gas is cooled to condense it to a liquid - -200 degrees.
• Water vapour condenses and is removed by absorbent filters.
• Carbon dioxide freezes at -79 degrees and is removed.
• Oxygen liquifies at -183 degrees at the bottom of the column.
• Nitrogen liquifies at -196 degrees at the top of the column.

• Positive ions held together by a sea of delocalised electrons.
• Conducts electricity when solid and liquid as delocalised electrons can move between ions.
• Medium - high melting and boiling points.
• All metals, except mercury, are solid at room temperature.
• Insoluble.