Physical properties in Covalent Compounds

Covalent discrete molecular substances ELEMENTS Hydrogen Oxygen Nitrogen Halogens Sulphur Phosphorus COMPOUNDS Water Carbon dioxide Sulphur dioxide …millions of others

Melting/boiling points Covalent discrete molecular substances (elements and compounds) have high/low melting points. This is because they are made up of discrete molecules held together only by weak forces The molecules are separated using high/low energy NOTE: The covalent bonds are NOT broken

Conductivity Do not conduct in any state because there are no free moving charged particles (they are made up of atoms/molecules/ions which are neutral)

Covalent Networks substances ELEMENTS Boron Silicon Carbon (diamond or graphite) COMPOUNDS Silicon dioxide …a few others

Covalent network substances have high/low melting points. This is because they are made up of a huge network of atoms, all held together by covalent bonds which are very strong/weak. The atoms are separated using high/low energy NOTE: The covalent bonds ARE broken Melting/boiling points