chemistry vocabulary

3. a positively charged elementary that is a fundamental constituent of all atomic nuclei
4. a representation of a substance using symbols for its constituent elements
5. an atom or molecule with a net electric charge due to the loss or gain of one or more electrons
6. samples of a pure compound always contain the same elements
10. any element in group 2 of the periodic table
14. molecules composed only of two metals
18. an elementary particle that is a fundamental constituent of matter
20. any of the gases in group O (18) of the periodic table
21. the number of positive charges of protons in the nucleus of an atom of a given element

1. theory that matter consists of of invisible particles called atoms
2. a table of chemical elements arranged in order of atomic number
7. any of the elements in group ia 1 of the periodic table
8. an element whose properties are intermediate between metals and solid non metals
9. any element in group 17 of the periodic table
11. any of the set of metallic elements in groups 4-12 of the periodic table
12. the integer number nearest in value to the atomic weight of an atom and equal to the number of nucleons
13. an ionic species having a negative charge
15. an ionic bond is a chemical link between two atoms caused by an electrostatic force
16. a positively charged ion
17. a fundamental group of atoms in a molecule serving as a base
19. any of two or more forms of a chemical element