Covalent Compounds Flashcards
What is covalent bonding
share electrons between atoms
a covalent bond=shared pair of electrons between atoms
Covalent bonds occur in:
- non-metallic Elements e.g. oxygen (O2)
- compounds of non metals e.g. Sulfur dioxide (SO2)
Covalent bonds are very ?
Strong
Small molecules contain a ?
Relatively small number of non-metal atoms joined together by covalent bonds —> these molecules have no overall electrical charge, so they cannot conduct electricity
Substances that consist of small molecules usually have a ? Why?
Low melting and boiling points, this is because the have weak INTERMOLECULAR forces (forces of attraction between the molecules)
The larger the molecules are, _____
The stronger the intermolecular forces between the molecules become —> so they have higher melting and boiling points
Fluorine and chlorine are __
Bromine is __
Iodine is ___
(GROUP 7)
1) F and Cl are GASES
2) B is a liquid
3) I is a solid
THIS IS BECAUSE THE MOLEVULES GET LARGER AND THEIR MELTING AND BOILING POINTS INCREASE DOWN GROUP 7
Diamond is a form of carbon:
- giant, rigid covalent structure (lattice)
- each carbon atoms form four strong covalent bonds with other carbon atoms
- all the strong covalent bonds mean that it is a very hard substance with a very high melting point
- no charged particles, so it doesn’t conduct electricity
Graphite is another form of carbon:
- giant covalent structure and a very high melting point
- each carbon atoms forms three covalent bonds with other carbon atoms
- this results in a layered, hexagonal structure
- layers are held together by weak intermolecular forces
- this means that the layers can slide past each other, making it soft and slippery
- one electron from rasch carbon atoms in graphite is delocalised, this allowed graphite to conduct heat and electricity
Silicon dioxide (or Silica, SiO2) has a lattice structure similar to diamond:
- each oxygen atom is joined to two silicon atoms
- each silicon atoms is joined to four oxygen atoms
