| A | B |
|---|
| Mendeleev | put elements in order of atomic mass |
| thirty | number of elements known at the time of Napoleon in1805 |
| mercury | only liquid metal |
| bromine | only liquid non-metal |
| period | rows of elements in periodic table |
| groups | columns of similar elements in the periodic table |
| iodine | solid element in same group as chlorine |
| two | number of times heavier Mg is greater than C |
| transition metals | contains all the really useful metals in the periodic table |
