Chemistry 1a - Atoms and Elements

Chemistry 1a - Atoms and Elements

1. Atoms and Elements

   • The Nucleus
     • The middle of the atom
     • Contains protons and neutrons
       • Protons are positively charged
       • Neutrons have no charge (Neutral)
     • The nucleus has a positive charge overall because of the protons
     • They are tiny compared to the rest of the atom
   • The Electrons
     • They move around the nucleus
     • Negatively charged
     • Tiny but cover a lot of space
     • They occupy shells around the nucleus

2. Protons = Electrons

   • Atoms have no charge overall, meaning they are neutral
   • The charge of the electrons is the same size as the charge on the protons, but opposite
   • The number of protons always equals the number of electrons in an atom
   • Is some electrons are added or removed, the atom becomes charged and is then an ion

3. Elements consist of one atom

   • Atoms have different numbers of protons, neutrons and electron.
     • The number of protons in the nucleus decide what type of atom it is
   • For example, an atom with one proton in its nucleus is hydrogen and an atom with two protons is helium
   • There are about 100 different elements
     • Everyday examples of elements are:
       • Nitrogen
       • Oxygen
       • Copper
       • Aluminium
       • Iron
   • All the atoms of a particular element have the same amount of protons and different elements have atoms with different numbers of protons,
   • If a substance only contains one type of atom it's called an element