Chemistry (C1)

Chemistry (C1)

1. Atoms and Elements

   • Number of Protons = Number of Electrons
   • The Nucleus contains Protons and Neutrons.
   • Protons are positively charged. Neutrons have no charge. Electrons are negatively charged.

2. The Periodic Table

   • Atoms are represented by symbols.
   • Vertical columns are called groups.
   • Elements in a group all have the same number of electrons in their outer shell.

3. Electron Shells

   • • Electrons move around the Nucleus. They occupy shells. The first shell has a maximum of 2 electrons, whilst the rest have a maximum of 8.
   • In most atoms (other than the Noble Gases), the outer shell isn't full, which makes them want to react to fill it.

4. Compounds

   • Atoms join together to make compounds.
   • A compound formed using a metal and a non-metal are bonded using ionic bonding as they from ions. The one that loses becoms a positive ion. The one that gains becomes a negative ion.
   • A compound formed from non-metals consists of molecules. Each atom shares an electron with another atom. This is covalent bonding.
   • The properties of compounds are completely different.
   • The formula shows what atoms are in a compound. CO2 is a compound containing 1 Carbon atom and 2 Oxygen atoms.

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