The Periodic Table

What is the periodic table?

  • The periodic table is the elements organised in order of increasing atomic number
  • Arranged into groups and periods
  • Periodic: regular intervals

Groups

Columns going down

Same group: similar chemical properties

Same number of electrons on their outer shell

8 Groups

  • i: Alkali metals
  • ii: Alkaline earth metal
  • iii: Transition metals
  • vii: Halogens
  • viii: Noble inert gases

Periods

Rows going across

Labelled => N=1 to N=7

Same period: Same number of orbits/shells

Important terms

Isotope

Atoms of the same element that have different number of neutrons

Example: Carbon

Stability

Elements that have a full outer shell => very unreactive

Octet Rule

Atoms must have a full outer shell (8)

Molecules

A molecule is a group of atoms joined together. It is the smallest particle of an element or compound that can exist independently

Example: Hydrogen (H2) and Water (H2O)

Chemical bond: force holding atom together

Ionic bonding

Ion: charged atom or group of atoms

Ionic bonding steal or give an electron

  • If an atom gives away an electron => positively charged +
  • If an atom receives/steals an atom => negatively charged -

Example: Sodium chloride => NaCl

Sodium chloride

Covalent Bonding

Sharing electrons

Example: water => H2O

Water