Periodic Table Crossword Puzzle

2. it is a heavy metal that is denser than most common materials
7. it is a colorless, dense, odorless noble gas found in Earth's atmosphere in trace amounts
10. it is a nonmetal with properties that are intermediate between the elements above and below in the periodic table sulfur and tellurium, and also has similarities to arsenic
11. the heaviest of the stable halogens, it exists as a lustrous, purple-black non-metallic solid at standard conditions that melts to form a deep violet liquid at 114 degrees Celsius, and boils to a violet gas at 184 degrees Celsius
13. it is a very soft, silvery-white metal in the alkali metal group
14. it was identified as a new element in 1781 and first isolated as a metal in 1783
16. it belongs to group 14 of the periodic table
18. a chemical element with the symbol Hf and atomic number 72
19. it is in group 18 of the periodic table and is a noble gas
20. it is a post-transition metal that makes up 0.21 parts per million of the Earth's crust

1. it is named after Tantalus, a villain from Greek mythology
3. it occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal
4. it is a chemical element with the symbol Cs and atomic number 55
5. it is a soft, ductile, and silvery-white metal that tarnishes when exposed to air, and it is soft enough to be cut with a knife
6. it is a silvery metal that characteristically has a faint yellow hue
8. it is a chemical element with the symbol Ne and atomic number 10
9. it is a silvery-gray, heavy, third-row transition metal in group 7 of the periodic table
12. it was referred to as eka-caesium
15. it is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula S₈
17. it is a colourless, odourless, tasteless gas that is the most plentiful element in Earth's atmosphere and is a constituent of all living matter