Science crossword week 6 by andrew green

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Across
  1. 3. table) group, in chemistry, a column in the periodic table of the chemical elements.
  2. 4. the smallest unit of an element that maintains the properties of that element.
  3. 7. a substance that cannot be separated or broken down into a simpler substances by chemical means
  4. 8. The number of protons of an atom;the atomic number is the same for all atoms of an element.
Down
  1. 1. a subatomic particle that has a positive charge and that is located in the nucleus of an atom
  2. 2. table) The periodic table has undergone extensive changes in the time since it was originally developed by Mendeleev and Moseley.
  3. 5. a subatomic particle that has no charge and that is located in the nucleus of an atom.
  4. 6. mass number, in nuclear physics, the sum of the numbers of protons and neutrons present in the nucleus of an atom.