Chemistry Revision

5. A Noble gas.
7. The Law of Conservation of Mass in chemistry means that any chemical equation must be ____________.
9. Elements in group 7 are known as _________.
10. Chemistry is the study of _____________.
11. Cobalt is found in the ____________ metal region of the periodic table.
14. ___________ go across the periodic table.
16. Group 8 elements have a full outer shell. This makes them ___________.
18. Reactions that release energy.
19. Ions that have a negative charge.
21. The charge electrons carry.
22. Beryllium has an atomic number of four and a mass number of nine. How many neutrons does it have?
23. _______ go down the periodic table.
24. The region in the atom that contains the protons and neutrons.
25. Ions that have a positive charge.

1. The particles in a solid _________.
2. The overall charge of an atom.
3. Carbon-13 has __________ neutrons.
4. The substances we begin a chemical reaction with.
6. The number of protons is ________ to the number of electrons in an atom.
8. Reactions that absorb energy.
12. The charge electrons carry.
13. The name given to atoms of the same element which have different mass numbers.
15. Elements which demonstrate characteristics of metals and non metals are called _____________.
17. Chlorine-37 has ___________ protons.
20. Group 1 metals react strongly with this substance.
21. The substances we end up with after a chemical reaction has occurred.