| A | B |
|---|
| element | A substance that can't be broken down into simpler chemical substances. |
| atom | The smallest particle of an element that has the characteristics of that element. |
| nucleus | The center of an atom made of protons and neutrons. |
| isotope | Atoms of the same element that have different numbers of neutrons. |
| compound | A substance composed of atoms of two or more different elements that are chemically combined. |
| covalent bond | Bond formed by the sharing of electrons between two atoms. |
| molecule | A group of atoms held together by covalent bonds and having no overall charge. |
| ion | A charged particle (may be positively or negatively charged). |
| ionic bond | Bond between two atoms of opposite charge. |
| metabolism | All the chemical reactions that take place within an organism. |
| pH | The measure of how acidic or basic a solution is. |
| solution | A mixture in which two or more substances (solutes) are dissolved evenly in another substance (solvent). |
| acid | Any substance that forms hydrogen ions (H+) in water. |
| base | Any substance that forms hydroxide ions (OH-) in water. |
