The Periodic Table (DP IB Chemistry): Revision Note

The Periodic Table

• The Periodic Table is a list of all known elements arranged in order of increasing atomic number, from 1 to 118

• The elements are arranged so that:

  • Atoms with the same number of shells are placed together

  • Atoms with similar electronic configurations in the outer shell are grouped together

Periods and groups

• The elements are arranged in rows (called periods) and columns (called groups)

• Each period corresponds to the number of electron shells occupied in an atom

  • E.g. Elements in period 2 (Li to Ne) all have 2 electron shells

• Each group contains elements with the same number of valence electrons, resulting in similar chemical properties

• Group numbers can be shown as Group 1–18 (IUPAC format)

Special cases:

• Hydrogen is placed in its own group because its properties do not match any one group closely

• Helium is placed in Group 18 because it shares the unreactive nature of the noble gases, despite having only 2 electrons

The Periodic Table

Metals, non-metals and metalloids

• The Periodic Table can also be divided based on the type of elements:

  • richa: Found on the left and centre of the table (s- and d-blocks, and part of the p-block)

    • Good conductors of heat and electricity

    • Malleable / ductile

  • Non-metals: Found on the right-hand side of the table (p-block)

    • Poor conductors

    • Brittle when solid

    • Often form acidic oxides

  • Metalloids: Found along a diagonal boundary between metals and non-metals

    • Exhibit properties of both metals and non-metals

    • Includes elements like boron, silicon, arsenic, antimony

Blocks of the Periodic Table

• All elements belong to one of four blocks depending on their electron configuration:

  • s-block: Groups 1 and 2 plus helium

    • Outer electrons are in s orbitals

  • p-block: Groups 13 to 18

    • Outer electrons are in p orbitals

  • d-block: Transition metals (Groups 3 to 12)

    • Outer electrons are in d orbitals

  • f-block: Lanthanides and actinides

    • Outer electrons are in f orbitals

• These blocks are useful for predicting:

  • Reactivity

  • Oxidation states

  • Typical bonding behaviour

Periodicity

• The physical and chemical properties of elements follow clear patterns across periods and down groups

• These repeating trends are called periodic trends and are the basis for the field of periodicity

• Elements in the same group show similar reactivity, and properties change predictably across each period