Science: Periodic Table and Elements Review

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Across
  1. 3. have two or more elements in their structure.
  2. 5. a substance that cannot be broken down into smaller components through chemical reactions.
  3. 6. everything in the universe is made of this.
Down
  1. 1. the smallest particle of an element that still has all its properties.
  2. 2. have two or more atoms of the same element in their structure.
  3. 4. has definite physical properties and a definite chemical composition.