• How big are atoms?
  Atoms are about a ten millionth of a millimeter across and weigh 100 ...

• What are noble gases?
  Group 0 is the furthest right-hand column of the periodic table. This ...

• What is a molecule?
  Quite often, atoms cannot exist by themselves, and must always join ...

• Why are some elements reactive?
  Elements are reactive if they readily gain or lose electrons. ...

• What are electrons?
  Electrons are the very tiny electrically charged particles that whizz ...

• Why is carbon so special?
  Carbon is the most friendly element in the Universe. With four ...

• What holds atoms together?
  Electrons are held to the nucleus by electrical attraction - because ...

• Who discovered radium?
  The Polish-French physicist Marie Curie (1867-1934), born Marya ...

• What is atomic mass?
  Atomic mass is the 'weight' of one whole atom of a substance - which ...

• What are the lanthanides?
  The lanthanides are a group of 15 elements in the middle of the ...