All matter is made of tiny particles that cannot be created or destroyed.
Atoms of one element share the same mass and properties; different elements differ.
Atoms combine in simple whole-number ratios to form compounds.
Atoms share one or more pairs of valence electrons to complete their outermost shell.
One atom gives up electrons, another accepts them — opposite charges then attract.
Two H atoms share one electron each — a single bond.
The prefix di- means 2 oxygen atoms bonded to carbon.
The prefix hexa- means 6 fluorine atoms bonded to sulfur.
Usually soluble in water; conduct electricity only when dissolved or molten, since the ions become free to move; high melting points.
Usually soluble in kerosene or petrol; generally don't conduct electricity even when dissolved; low melting points.
Mass is unchanged before and after a chemical reaction.
A compound's elements always combine in a fixed mass ratio.
A neutral group of atoms that exists independently.
The force holding atoms together in a molecule or crystal.
Formed by atoms sharing electrons.
Formed by atoms transferring electrons (forming ions).
Total mass of a covalent molecule or an ionic formula unit.
Combining capacity — the charge or bonds an atom forms.