Solve these clues to fill the grid.
- That which has mass and occupies space
- 3 Across
- A stable particle with positive charge equal to the negative charge of an electron (plural)
- 6 Across
- A particle that is electrically charged (plural)
- 8 Across
- The order of an element in Mendeleyev's table of the elements
- 10 Across
- An elementary particle with negative charge (plural)
- 11 Across
- One of two or more atoms with the same atomic number but with different numbers of neutrons (plural)
- 12 Across
- English chemist and physicist who formulated atomic theory and the law of partial pressures
- 13 Across
- United States classical archaeologist noted for leading the excavation of the Athenian agora
- 1 Down
- The sum of the ___ of neutrons and protons in an atomic nucleus
- 2 Down
- An elementary particle with 0 charge and mass about equal to a proton (plural)
- 4 Down
- The smallest component of an element having the chemical properties of the element (plural)
- 5 Down
- A unit strength of a radioactive source equal to one million disintegrations per second
- 7 Down
- Center of an atom or a cell
- 9 Down