atoms

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Across
  1. 3. Ancient Greek philosopher who first suggested matter is made of small, indivisible particles called atoms
  2. 6. A particle with no charge found in the nucleus
  3. 7. An atom that has gained or lost electrons and has a charge
  4. 8. Scientist who said electrons move in fixed energy levels around the nucleus
  5. 9. number The number of protons in an atom
  6. 10. Scientist who discovered that atomic number is based on the number of protons in an atom
  7. 12. Scientist who discovered the nucleus using the gold foil experiment
Down
  1. 1. electrons Electrons in the outermost energy level of an atom that are involved in bonding
  2. 2. Tiny particles that make up protons and neutrons
  3. 3. Scientist who developed the first modern atomic theory and said atoms are solid, indivisible spheres
  4. 4. number The total number of protons and neutrons in an atom
  5. 5. A positively charged particle found in the nucleus
  6. 7. Atoms of the same element with different numbers of neutrons
  7. 9. The smallest unit of matter that still keeps the properties of an element
  8. 11. A negatively charged particle that moves around the nucleus
  9. 13. Scientist who discovered the electron and proposed the “plum pudding” model of the atom