3.1.1

The Periodic Table

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The Periodic Table - Groups and Periods

The periodic table is arranged into periods and groups.

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The periodic table

  • The periodic table is the table that organises all the elements into groups and periods.
    • The elements are arranged in order of proton number, starting with hydrogen that has the proton number of 1.
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Periods

  • A period is a row in the periodic table.
    • Elements in the same period have their valence electrons in the same shell.
  • The diagram highlights Period 3.
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Period example

  • Magnesium and sulfur are in the same period.
    • In simple terms, they have the electron configuration 2,8,2 and 2,8,6 respectively.
    • So, their valence electrons are in the same shell.
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Groups

  • A group is a column in the periodic table.
  • Elements in the same group have their electrons in similar orbitals.
    • They often have very similar properties.
    • A Group n element has n valence electrons.
      • E.g. Carbon is in Group 4 and has 4 valence electrons.
  • The diagram highlights Group 7.
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Group example

  • The halogens are all in Group 7.
    • Fluorine's simplified electron configuration is 2,7.
    • Chlorine's is 2,8,7.
      • We see they both have the same number of valence electrons.
  • We also know that halogens have very similar chemical properties.

Periodic Table - Blocks

The periodic table can be organised into four sections. These are labelled s, p, d and f blocks.

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The s block

  • The two leftmost columns make up the s block.
    • This is called the s block because elements in it have all their valence electrons in s orbitals.
    • Note, Helium is also an s block element because it has the electron configuration 1s2.
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The p block

  • The six rightmost columns make up the p block.
    • This is called the p block because elements in the p block have a partially filled p sub-shell.
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The d block

  • The d block lies between the s and p blocks.
    • Elements in the d block have a partially filled d sub-shell.
    • Elements in the d block are often called transition metals.
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The f block

  • The f block is detached along the bottom of the periodic table.
    • Elements in the f block have a partially filled f sub-shell.
    • These elements are referred to as the lanthanides and the actinides (top and bottom row respectively).

Jump to other topics

1Physical Chemistry

1.1Atomic Structure

1.2Amount of Substance

1.3Bonding

1.4Energetics

1.5Kinetics

1.6Equilibria

1.7Redox

2Physical Chemistry 2 (A2 Only)

3Inorganic Chemistry

4Inorganic Chemistry 2 (A2 Only)

5Organic Chemistry 1

6Organic Chemistry 2 (A2 Only)

6.1Optical Isomerism (A2 Only)

6.2Aldehydes & Ketones (A2 Only)

6.3Carboxylic Acids & Esters (A2 Only)

6.4Aromatic Chemistry (A2 Only)

6.5Amines (A2 Only)

6.6Polymers (A2 Only)

6.7Biological Organic (A2 Only)

6.8Organic Synthesis (A2 Only)

6.9NMR Spectroscopy (A2 Only)

6.10Chromatography (A2 Only)

6.11A-A* (AO3/4) - Organic 2

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