atom

• Physics does not inquire into the essence of atoms or of light .
  物理学并不探求原子或光的本质。
• The magnetic field of an atom is usually dominated by the electrons .
  原子的磁场通常由电子决定。
• Each element is composed of identical atoms of a single kind .
  每种元素由单一种类的相同原子组成。
• One result is that from many atoms an electron is expelled .
  其一是使从许多原子中排斥出一个电子。
• Halogen atoms contain seven electrons in their valence shell .
  卤原子在它们的介电子层含有七个电子。
• One atom of oxygen is linked to the nitrogen atom by a double bond .
  一个氧原子以双键与氮原子相连。
• Virtually all other atoms exist in insignificant quantities .
  实际上所有其它原子都以不大的数量存在。
• Now consider applying an external magnetic field to the hydrogen atom .
  现在考虑加一外磁场于氢原子。