It provides a way to test a hypothesis
The number of electrons. The valence (outer) shell is particularly important.
Each carbon atom is covalently bonded to four other carbon atoms. A lot of energy is needed to separate the atoms in diamond. This is because covalent bonds are strong, and diamond contains very many covalent bonds. This makes diamond's melting point and boiling point very high.
Krypton. The atomic radius decreases as you go across a period.
Sorry but I only know a few
17- decomposers
18- decomposition
21- 10% is lost so 90%
