| A | B |
|---|
| activation energy | the minimum amount of energy needed to start a chemical reaction |
| atom | the smallest unit of an element that maintains the chemical properties of that element |
| atomic number | the number of protons in the nucleus of an atom; the same for all atoms of an element |
| chemical bond | the attractive force that holds atoms or ions together |
| chemical reaction | the process by which one or more substances change to produce one or more different substances |
| compound | a substance made of atoms of two or more elements joined by chemical bonds |
| covalent bond | a bond formed when atoms share one or more pairs of electrons |
| electron | a subatomic particle that has a negative charge |
| element | a substance that can not be separated or broken down into simpler substances by chemical means; all atoms of an element have the same atomic number |
| energy | the ability to do work |
| ion | an atom, radical or molecule that has gained or lost one or more electrons and has a positive or negatitve charge |
| ionic bond | the attractive force between oppositely charged ions, which form when electrons are transferred from one atom to another |
| mass | a measure of the amount of matter in an object; a fundamental property of an object that is not affected by the forces that act on the object, such as gravity |
| mass number | the sum of the number of protons and neutrons in the nucleus |
| matter | anything that has mass and takes up space |
| molecule | a group of atoms that are held together by chemical forces; the smallest unit of matter than can existy by itself and retain all of a substance's chemical properties |
| neutron | a subatomic particle that has no charge and that is located in the nucleus of an atom |
| nucleus (in physical science) | an atoms's central region, which is made up of protons and neutrons |
| orbital | a region in an atom where there is a high probability of finding electrons |
| product | a substance that forms in a chemical reaction |
| proton | a subatomic particle that has a positive charge and that is located int he nucleus of an atom; the number of protons of the nucleus is the atomic number, which determines the identity of an element |
| reactant | a substance or molecule that participates in a chemical reaction |
