P1 - Matter

P1 - Matter

1. Atoms

   • The atomic model
     • Dalton’s model (1803)
       • John Dalton thought that all matter was made of tiny particles called atoms, which he imagined as tiny solid balls.-
     • Thomson’s model (1897)
       • J.J. Thomson discovered the electron. The plum pudding model
     • Bohr’s model (1913)
       • Using mathematical ideas, he showed that electrons occupy shells or energy levels around the nucleus.
   • 1 X 10 ^-10

2. Density

   • mass of a unit volume of a material substance in grams per cubic centimetre