Topic 1 -Atomic structure and the periodic table

Atoms
Atoms contain protons, neutrons and electrons

• radius of about 0.1 nanometers
  The nucleus
• middle of atom
• contains protons and neutrons
• positively charged
  The electrons
• orbit the nucleus
• negatively charged
• virtually have no mass
  Number of protons = number of electrons
• atoms are neutral
• in an ion the number of protons doesn’t equal number of electrons
  Atomic number and mass number describe an atom
• nuclear symbol = proton…