| A | B |
|---|
| matter | anything that takes up space and has mass; the characteristics of matter are determined by its atoms |
| atom | the smallest particles of an element that still have all the properties of that element; the building blocks of matter |
| element | a form of matter that contains only one kind of atom; cannot be broken down into simpler substances |
| proton | one of the two particles that make up the nucleus of an atom; it has a positive electric charge |
| electron | one of the three subatomic particles; moves around the nucleus of an atom; has a negative electric charge |
| mass number | the sum of the number of protons and neutrons in an atom's nucleus |
| atomic number | equals the number of protons in the nucleus of an atom |
| isotope | atoms of the same element that have different numbers of neutrons in their nuclei, but the same number of protons |
| molecule | the smallest particle of a compound that still keeps all the properties of the compound; it is formed by the combining of two or more atoms |
| compound | a type of matter containing two or more chemically combined elements and having physical and chemical properties different from each of the elements in it |
| chemical property | characteristics of an element or compound that determine how it will react with other elements or compounds |
| ion | an atom with an electrical charge |
| mixture | a combination of different substances in which each of the components keeps its own physical and chemical properties despite being mixed |
| solution | a kind of mixture formed when one substance is dissolved in another |
| physical property | characteristics of an element or a compound that affect weight, color, density, etc., but don't affect how it will react with other elements or compounds |
| density | how highly packed a substance's molecules are; the mass of an object divided by its volume, in g/cm3 |
| nuclear energy | an alternate energy source produced from atomic reactions |
| fission | the splitting of the nuclei of atoms of heavy elements to release energy |
| nuclear waste | radioactive waste material produced by nuclear power plants; must be safely stored to prevent it from entering the environment |
