Science - Atoms

Science - Atoms

1. Structure of an Atom

   • Atoms consist of subatomic particles eg electrons, neutrons, protons
     • Electrons
       • electrically charges
         • relative charge of -1
       • electron shells
         • Electrons are found in the regions around the nucleus called shells
         • electrons fill shells from inside shell first
           • The first (inner) shell can hold 2 electrons
           • The second shell can hold 8 electrons
           • The third shell can hold 8 electrons
       • all chemical reactions are possible because of the behaviour of electrons
     • neutrons
       • neutral
     • Protons
       • electrically charged
         • relative charge of +1
       • number of protons in an atom is called its atomic number

2. Isotopes

   • Atoms are the same element with the same number of electrons and protons, but a different number of neutrons