Term | Definition |
matter | anything that has mass and takes up space |
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 the gravititraditional force |
element | a substance that cannot be separated or broken down into simpler substances by chemical means; all atoms of an element have the same atomic number |
atom | the smallest unit of an element that maintains the chemical properties of that element |
nucleus | in physical science, an atom's central region, which is made up of protons and neutrons |
proton | a subatomic particle that has a positive charge and that is located in the nucleus of an atom; the number of protons of the nucleus is that atomic number which determines the identity of an element |
neutron | a subatomic particle that has no charge and that is located in the nucleus of an atom |
atomic number | the number of protons in the nucleus of an atom; the atomic number is the same for all atoms of an element |
mass number | the sum of the numbers of protons and neutrons in the nucleus of an atom |
electron | a subatomic particle that has a negative charge |
orbital | a region in an atom where there is a high probability of finding electrons |
isotope | an atom that has the same number of protons (or the same atomic number) as other atoms of the same element do but that has a different number of neutrons (and thus a different atomic mass) |
compound | a substance made up of atoms of two or more different elements joined by chemical bonds |
chemical bond | an attractive force that holds atoms or ions together |
covalent bond | a bond formed when atoms share one or more pairs of electrons |
molecule | a group of atoms that are held together by chemical forces; a molecule is the smallest unit of matter that can exist by itself and retain all of a substance's chemical properties |
ion | an atom, radical, or molecule that has gained or lost one or more electrons and has a negative or positive charge |
ionic bond | the attractive force between two oppositely charged ions, which form when electrons are transferred from one atom to the other |