Across
- 3. the smallest unit of ordinary matter that forms a chemical element.
- 5. appearing or occurring at intervals.
- 7. relating to an atom or atoms.
- 9. an essential or characteristic part of something abstract.
- 13. an inert gaseous element of the noble gas group
- 15. a colourless, odourless reactive gas
- 16. a rare radioactive gas belonging to the noble gas series.
- 18. a substance made by mixing other substances together.
- 19. a silver-white metal of the alkaline earth series
- 20. a stable subatomic particle with a charge of negative electricity
Down
- 1. a stable subatomic particle occurring in all atomic nuclei
- 2. A chemical compound is a chemical substance composed of many identical molecules composed of atoms from more than one element held together by chemical bonds.
- 4. the emission of ionizing radiation or particles caused by the spontaneous disintegration of atomic nuclei.
- 6. a non-metal which has two main forms
- 8. a subatomic particle of about the same mass as a proton but without an electric charge
- 10. a hard grey metal of the transition series
- 11. a radioactive metal occurring in nature only as a product of radioactive decay of uranium.
- 12. a hard silver-grey metal of the transition series
- 14. a colourless, odourless, highly flammable gas
- 17. are variants of a particular chemical element which differ in neutron number