Chemistry

2. A substance consisting of atoms
3. The number of protons in the element
5. Vertical column in the periodic table
7. Composed of two or more separate elements
8. The positively charged centre of the atom containing protons and neutrons
12. The electrons on the atom's outermost electron shell
14. A chemical link between two atoms caused by the electrostatic force between oppositely-charged ions in an ionic compound.
16. Elements 90 to 103
17. A positively charged atom
18. Any of the fifteen metallic elements from lanthanum to lutetium on the periodic table.
20. Group 17 of the periodic table. Reactive non-metallic elements
24. The smallest component of an element. Makes up all matter
25. An abbreviation of a chemical element
27. Elements that have the properties of both metals and non-metals
29. Determines the negativity of an element
30. Any of the gases in group 18 of the periodic table

1. state When the atom has an electron in a higher than normal level than its ground state
2. the distribution of electrons in the electron shells
3. An atom that is negatively charged
4. The state of electrons in the atom
6. The number protons and neutrons together
9. The elements in the centre of the periodic table between groups 2 and 3
10. Horizontal rows of the periodic table
11. The outermost electron shell
13. Any of the elements found in group 1 of the periodic table. Very reactive elements that readily lose their one valence electron in ionic bonding
15. A particle of light
19. An atom that has gained or lost electrons
21. state The lowest energy state of an atom or other particle
22. shell Grouping of electrons orbiting the nucleus
23. An atom that has gained or lost neutrons
26. Atomic structure that consists of a small, positively charged nucleus orbited by negatively charged electrons
28. A subatomic particle with the same mass as a proton but without an electric charge. Holds the nucleus together