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- 2. The metal is fairly stable in air and does not oxidise as rapidly as some of the other rare-earth metals.
- 5. Is required in small amounts for life and is the only metal found in vitamins.
- 6. It oxidises rapidly in moist air and at elevated temperatures. The metal has unusual magnetic properties.
- 8. Has a bright silver lustre and is reasonably stable in air. It ignites in air at 150°C. It is a rare earth metal.
- 11. Is a shiny, white, soft, and ductile metal, and takes on a bluish tinge when exposed to air at room temperatures for a long time. The metal starts to oxidize in air at high temperatures.
- 12. It is very hard and brittle, making it very hard to machine, form, or work. It is the most corrosion resistant metal known.
- 13. Is a beautiful silvery-white metal, when pure, and is malleable and ductile.
- 15. Is somewhat rare and expensive, although not as expensive as gold
- 17. Great care is required while handling promethium as a consequence of its radioactivity.
- 19. It is not acted on by air at room temperature, but burns brilliantly when heated with the formation of white fumes. It is a poor conductor of heat and electricity.
- 21. Is a p-type semiconductor, and shows varying conductivity with crystal alignment. Its conductivity increases slightly with exposure to light.
- 22. Named after Alfred Nobel who discovered dynamite.
- 23. Occurs in some soils in amounts sufficient to produce serious effects on animals feeding on plants such as locoweed (an American plant) grown in such soils.
- 26. A much more abundant element in the sun and certain stars than on earth.
- 28. Is a synthetic element that is not present in the environment at all. It has no uses.
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- 1. Chemical properties are largely unknown. Is a radioactive rare earth metal.
- 3. The metal is characterised by a spectrum containing two bright lines in the blue (accounting for its name). It is silvery gold, soft, and ductile.
- 4. Has a higher melting point and lower density than platinum. It has a high reflectance and is hard and durable.
- 7. Is a metallic element, soft, and when pure is silvery white like lead. The metal oxidises very easily and it reacts with water or alcohol.
- 9. Dangerously radioactive.
- 10. Can be liquid at ambient temperature, but only on a hot day given that its melting point is about 40°C. It is a soft, silvery-white metallic element of the alkali metals group (Group 1).
- 13. Is one of the rarest and most expensive naturally occurring elements. The element is an α-emitter and is a radiological hazard similar to polonium.
- 14. Soft enough to be cut with a knife. It is one of the most reactive of the rare-earth metals. It oxidises rapidly when exposed to air.
- 16. Is a radioactive rare earth metal which must be handled with care to avoid contact, since it is a heavy α and γ emitter. It is named after America.
- 18. Is widely distributed throughout the animal kingdom. It is an important trace element and may be essential for utilisation of vitamin B.
- 20. Has more isotopes than any other element, all of which are radioactive.
- 21. Is almost completely immune to chemical attack at temperatures below 150°C, and is attacked only by hydrofluoric acid, acidic solutions containing the fluoride ion, and free sulphur trioxide.
- 24. Poor conductor of electricity. It is very resistant to corrosion but tarnishes upon exposure to air.
- 25. Its density is exceeded only by that of platinum, iridium, and osmium, and its melting point is exceeded only by that of tungsten and carbon. It is expensive but useful as a trace alloying agent.
- 27. Is an essential constituent of leaves, bones, teeth, and shells. The fifth most abundant element in the earth's crust and makes up more than 3% of the crust.