Matter

3. Atoms with the same number of protons, but different number of neutrons
9. A tiny particle that has mass and a positive charge
10. Two or more atoms held together by a covalent bond
11. A particle with approximately the same mass as a proton, but electrically neutral
13. The number of protons in an atoms nucleus
14. The attractive force of two ions of opposite charge
16. The change of one or more substances into other substances
17. An atom that gains or loses an electron
18. The sum of protons and neutrons in an atom
19. Electrons in the outermost energy level
20. A substance that produces hydrogen ions in water

1. A bond where two atoms share electrons
2. A homogeneous mixture
4. Anything that has volume and takes up space
5. A substance that cannot be broken down into simpler substances by physical or chemical means
6. Found in the center of the atom and made up of protons and neutrons
7. The force that holds the elements in a compound together
8. A substance that is composed of atoms of two or more different elements that are chemically combined
12. A particle with little mass and a negative electrical charge of the same magnitude as the positive charge of the proton
15. A substance that produces hydroxide ions in water
18. The bond between metal atoms