Elements of life

Elements of life

1. How the universe began

   • TBB! Forming H and traces of He.Clouds of H collapsed under gravity to generate temperatures and pressures high enough for nuclear fusion- stars formed.
   • Elements up to iron are formed when to smaller nuclei fuse to form a larger nuclei
   • The elements heavier than iron are formed in the supernova explosions of giant stars.
   • Elements can be identified in stars by looking at absorption lines on their spectra

2. atoms

   • timeline
     • 1) Dalton thought that atoms were indivisible (couldn‟t be split) spheres that react in whole numbers.
     • 2)Thomson discovered the electron and proposed the plum pudding model of the atom with the electrons spread through like currants in a cake.
     • 3)Rutherford discovered the nucleus by firing alpha particles at atoms. Most passed through proving most of the atom is empty space. A tiny fraction bounced back indicating a very tiny, very dense, positively charged nucleus in the centre of the atom
     • Explaining line spectra required the existence of electron energy levels (shells) at different distances from the nucleus. Finally quantum theory gives the best explanation of electron behaviour and bonding.
   • neutorns
     • charge 0, mass 1
   • electons
     • charge -1, mass 1/2000
   • protons
     • charge 1, mass 1