Across
- 4. — substance made of two or more elements
- 5. — layer of gases around Earth
- 7. — atmospheric gases that trap heat
- 9. — inert gas used in lamps
- 10. — long‑term rise in Earth’s temperature
- 16. — reactive Group 7 elements
- 18. — unreactive elements in Group 0
- 19. — combination of substances not chemically joined
- 24. — elements lacking metallic properties
- 27. — chart organising elements
- 29. — glowing stick used for gas tests
- 31. — simple hydrocarbon gas
- 33. — atoms with same protons but different neutrons
- 34. — removal of trees on a large scale
- 36. — reusing materials to reduce waste
- 37. — gas essential for respiration
- 38. — negatively charged particle
- 41. — forming solid crystals from solution
- 42. — gaseous form of water
- 43. — positively charged particle in the nucleus
- 44. — sound test for hydrogen gas
- 45. — elements that conduct heat and electricity
Down
- 1. — separating mixtures with close boiling points
- 2. — burning reaction with oxygen
- 3. — vertical position of an element in the periodic table
- 6. — ability to do work
- 8. — gas making up most of Earth’s atmosphere
- 11. — glowing noble gas in signs
- 12. — separating liquids by boiling points
- 13. — light noble gas in balloons
- 14. — containing only one substance
- 15. — readily undergoing chemical change
- 17. — energy source that replenishes naturally
- 20. — gas produced by respiration and combustion
- 21. — vertical tube in distillation
- 22. — coal, oil, and gas collectively
- 23. — mass per unit volume
- 25. — electron energy level
- 26. — separating solids from liquids
- 28. — neutral particle in the nucleus
- 30. — highest‑energy electron layer
- 32. — precise mixture designed for a purpose
- 35. — geological vents releasing molten rock
- 39. — containing unwanted substances
- 40. — lightest element