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Across 4. A strong yet low density metal used to build cans and aeroplanes 5. Metals that contain other elements 9. Two or more atoms chemically joined 10. Two or more things, not chemically joined 11. A method of splitting liquids with different boiling points 15. Shape memory alloys 16. Copper can be purified using this technique 17. Limestone is used to make this 18. Negative sub atomic particle 22. Neutral sub atomic particle 23. The ________ column is used to separate hydrocarbons 24. Metals need to be extracted from their ______ 25. Particulates in the air cause global ___________

Down 1. Burning hydrocarbons gives off this greenhouse gas (6,7) 2. Alkane with four carbon atoms 3. A strong building material that uses limestone 6. The most common magnetic element 7. Powdered limestone mixed with clay 8. Chromium nickel steel 12. Steel is an alloy of mostly iron plus some _______ 13. A mixture of hydrocarbons (5,3) 14. A molecule with carbon and hydrogen atoms 19. Contains only one type of atom 20. Very strong yet light metal used in armoured plating and rocket engines 21. Positive sub atomic particle