Chemistry Revision

2. Uncharged subunit of an atom.
4. Energy absorbed by an electron.
9. The number of protons (or electrons) of an atom.
10. Unstable state of an atom.
11. This substance tastes sour and sometimes bitter.
12. These metals are in a group of their own because they can form many charges and have different properties.
14. Energy released by an electron as light.
15. Detergents are an example of this substance.
16. A positively charged ion.

1. Normal state of an atom (neutral).
3. Negative subunit of an atom.
5. Elements that lose one electron belong to this group and are metals.
6. Total number of neutrons and protons of an atom.
7. An ion that contains more than one atom.
8. Positive subunit of an atom.
13. Two or more forms of the same element so that they have the same atomic number but different mass number.
17. A negatively charged ion.
18. Elements that are inert belong to this group of gases.