| A | B |
|---|
| vertical columns in the periodic table | groups |
| group 1 | alkali metals |
| reactivity of group 1 metals | increases down the group |
| Caesium | Cs |
| Potassium | K |
| group 7 | halogens |
| H2 + Cl2 | = 2HCl |
| Number of electrons in the outer shell of sodium | 1 |
| Number of electrons in the outer shell of chlorine | 7 |
| Group 0 | Noble gases |
| unreactive | inert |
| reactant + reactant | = product |
| exothermic | gives out heat |
| endothermic | takes in heat |
| speed up chemical reactions | catalysts |
| reaction between an acid and a base | neutralisation |
| the reaction between a metal and a compound of a less reactive metal | displacement |
