1.
Heavy, soft metal, symbol Pb
2.
Low-toxicity heavy metal with rainbow crystals
3.
Radioactive metalloid discovered by Curie
4.
Rare, radioactive halogen
6.
Extremely rare, highly radioactive alkali metal
7.
Radioactive alkaline earth discovered by Curie
9.
Weakly radioactive actinide
10.
Rare radioactive actinide
11.
Fuel for nuclear reactors
12.
First transuranic element
13.
Fissile actinide used in reactors and weapons
14.
Element in smoke detectors
15.
Named after Marie Curie
16.
Synthetic actinide element
17.
Used in neutron sources
19.
Synthetic actinide discovered in nuclear tests
20.
Named after Mendeleev, periodic table creator
