Periodic Table

3. My atomic symbol is Sn.
4. I live in Group 18 and Period 4.
6. I am a gas with the second smallest atomic mass.
7. I am the leader of Group 12, Period 4.
9. I was the name of a song by David Guetta featuring Sia.
11. My symbol is Na.
12. I have the atomic mass of 54.938.
14. I am named after the continent Europe.
15. I have two electrons in my inner layer, eight in my mid-layer, and 6 in my outer layer.
18. I am a soft gray alkaline earth metal, and is the fifth-most-abundant element by mass in the Earth's crust.

1. You have two atoms of me in a water compound.
2. My name comes from the Greek word lithos meaning 'stone'. I am the 4th element.
5. I am a transuranic radioactive chemical element with the symbol Pu.
8. My melting point is 321.1 °C.
10. I am the only liquid in Group 12.
11. I am the second element from Group 11.
13. My name comes from Greek Mythology: Niobe, daughter of Tantalus.
16. I am the last element of a group that is only gases.
17. The city of Johannesburg located in South Africa consists of some of the world's largest deposits of me.
18. 75% of the US 5-cent coin called nickel is me.