Across
- 2. the number of a chemical element in the periodic system, whereby the elements are arranged in order of increasing number of protons in the nucleus. Accordingly, the number of protons, which is always equal to the number of electrons in the neutral atom, is also the atomic number.
- 5. a soft, silvery white or grayish metal in Group 14 (IVa) of the periodic table. Lead is very malleable, ductile, and dense and is a poor conductor of electricity. Known in antiquity and believed by the alchemists to be the oldest of metals, lead is highly durable and resistant to corrosion, as is indicated by the continuing use of lead water pipes installed by the ancient Romans. The symbol Pb for lead is an abbreviation of the Latin word for lead, plumbum.
- 6. any of the series of elements with increasing atomic numbers that begins with lanthanum or cerium and ends with lutetium
- 7. the smallest particle of a chemical element that can exist.
- 8. the chemical element of atomic number 18, an inert gaseous element of the noble gas group. Argon is the commonest noble gas, making up nearly one per cent of the earth's atmosphere.
- 10. a positively charged elementary particle that is a fundamental constituent of all atomic nuclei. It is the lightest and most stable baryon, having a charge equal in magnitude to that of the electron.
- 12. the chemical element of atomic number 80, a heavy silvery-white metal which is liquid at ordinary temperatures.
- 14. a nonmetallic gaseous chemical element with atomic number 1 that is the simplest and lightest of the elements and that is used especially in the processing of fossil fuels and the synthesis of ammonia
Down
- 1. the chemical element of atomic number 83, a brittle reddish-tinged grey metal.
- 3. the chemical element of atomic number 27, a hard silvery-white magnetic metal.
- 4. a stable subatomic particle with a charge of negative electricity, found in all atoms and acting as the primary carrier of electricity in solids.
- 9. the chemical element of atomic number 33, a brittle steel-grey metalloid.
- 11. a precious shiny greyish-white metal, the chemical element of atomic number 47.
- 13. the chemical element of atomic number 86, a rare radioactive gas belonging to the noble gas series.
- 15. a colourless, odourless reactive gas, the chemical element of atomic number 8 and the life-supporting component of the air.