Periodic table

The Periodic Table - Fundamentals

  • The periodic table is a table of chemical elements, organised based on their atomic number, electronic configuration, and recurring chemical properties.
  • Elements are arranged in increasing atomic number from left to right, top to bottom.
  • The table has rows called periods and columns called groups.

Groups and Periods

  • Groups are vertical columns in the periodic table. Elements in a group share similar chemical properties.
  • Periods are horizontal rows on the periodic table. As you move from left to right in a period, there is a gradual change in properties.
  • The Group number (from 1 to 18) indicates how many electrons an element has in its outer shell.
  • The Period number tells us the number of energy levels or shells that an element has.

Block Classification

  • The periodic table is also split into blocks - the s-block, p-block, d-block, and f-block.
  • The s-block includes Groups 1 and 2, including hydrogen and helium. These elements are most reactive due to only 1-2 electrons in their outer shell.
  • The p-block is made up of Groups 13 to 18. These include all of the nonmetals (except hydrogen and helium), the semimetals, and the post-transition metals.
  • The d-block, also known as transition metals, includes Groups 3 to 12. These elements are less reactive, and they are good conductors of heat and electricity.
  • The f-block, which includes the Lanthanides and Actinides, appears separately at the bottom as they have different electron arrangements and properties.

Trends in the Periodic Table

  • Atomic Radius decreases from left to right across a period and increases down a group.
  • Electronegativity and Ionisation Energy increase from left to right across a period and decrease down a group.
  • Metallic Character decreases from left to right across a period and increases down a group.

Study of Main Group Elements

  • Group 1 elements (alkali metals) are highly reactive metals due to their single electron in the outer shell.
  • Group 17 elements (halogens) are highly reactive non-metals and exist as diatomic molecules in their standard states.
  • Group 18 elements (noble gases) have completely filled outer shells which make them very stable and highly unreactive.

Remember, understanding the Periodic table is crucial as it acts as a fundamental tool to understand the various aspects of chemistry including chemical reactions, chemical bonding, and the properties of substances.