| A | B |
|---|
| element | pure substance that cannot be broken down into any other substances by chemical or physical means |
| atom | small particle that makes up an element |
| chemical bonds | force of attraction between two atoms |
| molecules | groups of two or more atoms held together by chemical bonds |
| atoms | elements are different because their __________ are different |
| compound | pure substance made of two or more elements chemically combined in a set ratio |
| neutral | electrical charge of an atom because the number of electrons equals the number of protons |
| isotope | atoms with the same number of protons and a different number of neutrons |
| atomic number | used to identify an element and is equal to the number of protons |
| mass number | another name for atomic weight |
| electrons | particles in an atom that move rapidly around the nucleus and have a negative charge |
| change in termperature and/or release of gas | chemical changes involve what 2 things |
| chemical bonds | hold atoms together in a molecule |
| protons, neutrons, electrons | 3 smaller particles that make up an atom |
| nucleus | center of the atom which contains the protons and neutrons |
| protons | particles with a positive electrical charge |
| atomic mass unit (amu) | units used to measure atoms |
| protons and neutrons | particles in an atom that have a mass of about 1 amu |
| 1/2,000 amu | mass of an electron |
| mass number | sum of the protons and neutrons in the nucleus of an atom |
| atomic number | number of protons in an atom |
| volume | measurement of how much matter an object contains |
| increasing atomic number | order that elements are arranged in the periodic table |
| chemical formulas of a compound | H<SUB>2</SUB>O and CO<SUB>2</SUB> are considered |
| models | what scientists use to describe atoms |
| 13 | If an atom has 13 protons, how many electrons does it have? |
| chemical change | change that produces one or more new substances |
| molecules | O<SUB>2</SUB> and Li<SUB>2</SUB> are examples of this |
| atom | consists of a positively charged nucleus surrounded by a negatively charged electron cloud |
