C1 Atoms and Elements

C1 Atoms and Elements

1. Atoms contain nucleus (middle of atom)

   • Contains protons and neutrons
     • Protons - positive charge
     • Neutrons - no charge (neutral)
   • Nucleus has a positive charge
   • Atoms neutral because they have equal numbers of protons (+1) and electrons (-1)

2. Atoms contain Electrons

   • Move around the nucleus
   • Electrons - negitively charged
   • Electrons held in shells
     • 2, 8, 8

3. Number of protons is the same as the number of electrons

   • Atoms have no charge overall
   • If some electrons are added or removed, the atom becomes charged and is then an ion

4. Elements consist of one type of atom only

   • Number of protons in nucleus that decides what type of atom it is
   • An atom that consists of 2 protons (bottom number) is helium
   • Atoms of an element have the same number of protons
   • Atoms of a different element have a different amount of protons