Periodic Tables

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Across
  1. 2. A pure substance made of only one type of atom, defined by its number of protons.
  2. 6. Neutral (no charge) particles found in the nucleus of an atom.
  3. 8. Positively charged particles found in the nucleus of an atom.
  4. 9. The average mass of an atom of an element, usually measured in atomic mass units (amu). It reflects the number of protons + neutrons in the atom (averaged across isotopes).
  5. 10. A horizontal row in the periodic table. Elements in the same period have the same number of electron energy levels.
Down
  1. 1. Negatively charged particles that orbit the nucleus of an atom.
  2. 3. Atoms that have gained or lost electrons, giving them a positive or negative charge.
  3. 4. The number of protons in the nucleus of an atom. This number identifies the element.
  4. 5. A vertical column in the periodic table. Elements in the same group have similar chemical properties.
  5. 7. A one- or two-letter abbreviation used to represent an element (for example, H for hydrogen, O for oxygen).