Solve the following crossword puzzle with the help of the given clues.
Across:
1. The particles that build up an atom.
3. The arrangement of electrons in a succession of energy levels or shells.
5. An electrically neutral sub atomic particle that is part of the nucleus of an atom.
6. A whole number that represents the ability of an atom or a group of atoms to combine with other atoms or group of atoms.
7. The number of protons in the nucleus of an atom.
8. The smallest unit of an element that maintains the properties of an element. A sub – atomic particle that has a positive electric charge.
Down:
2. A substance that cannot be broken down into simpler substance by chemical means.
4. The total number of protons and neutrons present in the nucleus of an atom.
9. An ion that has a negative charge.
11 A sub – atomic particle with a negative electric charge.
12. Positively charged ions.