Atoms and Elements

Atoms and Elements

1. Nucleus

   • In the middle of an atom
   • Contains protons and neutrons
   • Protons are positively charged
   • Neutrons have no charge
   • Positively charged

2. Electrons

   • Move around the nucleus
   • Negatively charged
   • Occupy shells around the nucleus

3. Number of protons = Number of electrons

   • If electrons are added or removed the atom becomes charged and becomes an ion

4. Atoms have no charge

5. Elements consist of one type of atom only

   • The number of protons in the nucleus decides what type of atom it is

6. Atoms can be represented as symbols

   • Pb = Lead
   • Mg = Magnesium

7. Periodic Table

   • Puts elements with similar properties together
   • Vertical columns are called groups
   • All elements in the same group have the same number of electrons in their outer shell
   • Group 0 - Noble gases
   • Group 7 - Halogens
   • Group 1 - Alkali metals