Chapter 4 Vocabulary

4. a set of postulates defining atoms as the fundamental, indivisible particles of matter that combine in simple, fixed ratios to form chemical compounds
6. the dense, positively charged central core of an atom that contains protons and neutrons
7. the number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table.
8. a chart that organizes all known chemical elements in order of increasing atomic number, displaying them in rows (periods) and columns (groups) to show recurring patterns in their properties
9. a stable, negatively charged subatomic particle with negligible mass that orbits the positively charged nucleus of an atom in shells or orbitals
11. The smallest part of a substance that cannot be broken down chemically
13. a subatomic particle located in the nucleus of an atom that has no electric charge and a mass slightly greater than a proton
14. a vertical column of elements on the periodic table

1. the total count of protons and neutrons in its nucleus, which represents the atom's approximate mass
2. the negatively charged electrode by which electrons enter an electrical device.
3. a unit of mass used to express atomic and molecular weights, equal to one-twelfth of the mass of an atom of carbon-12.
5. the mass of an atom of a chemical element expressed in atomic mass units
8. a horizontal row in the periodic table, where each row corresponds to a specific number of electron shells or energy levels an atom of an element occupies
10. a variant of a chemical element that has the same number of protons but a different number of neutrons in its atomic nucleus
12. a positively charged subatomic particle found in the nucleus of every atom