First 20 Elements Quiz

1. Which pair of first-20 elements belongs to the same periodic-table group?

2. A neutral atom contains 12 protons. Which element is it?

3. Which formula contains only elements found among the first 20 elements?

4. An ion has 17 protons and 18 electrons. Which element is it an ion of?

5. Which chemical symbol belongs to potassium?

6. An atom has electrons arranged 2, 8, 1 across its shells. Which element is it?

7. Which element comes immediately after argon in atomic-number order?

8. Which of these first 20 elements is the noble gas at the end of Period 3?

9. Which element has atomic number 6?

10. Which sequence places three elements in increasing atomic-number order?

11. An atom's nucleus contains 6 protons and 8 neutrons. Which element is the atom?

12. A neutral atom has the electron-shell arrangement 2, 8, 8, 2. Which element is it?

13. A first-20 element is in Period 4 and commonly loses two valence electrons. Which element fits both clues?

14. In atomic-number order, which element belongs between magnesium and silicon?

15. An unknown element is in Period 3 and has two valence electrons. Which element is it?

16. Which element is the halogen in Period 2?