The Periodic Table

The Periodic Table

Basic Information

• The Periodic Table is a chart of all the chemical elements, arranged by their properties.

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

• The elements in a group have similar chemical properties because they have the same number of electrons in their outer shell.

Structure of the Periodic Table

• Group 1 elements are the alkali metals. They are very reactive metals that do not occur freely in nature.

• Group 2 elements are the alkaline earth metals. They are less reactive than alkali metals and can be found in the earth’s crust.

• Group 0 elements are the noble gases. They are very stable due to having full outer electron shells – meaning they hardly ever form compounds.

• Between Group 2 and Group 3, you can find the transition metals. These elements are characterised by multiple oxidation states, high melting points and coloured compounds.

• The elements in the two rows at the bottom are the lanthanides and actinides, including many man-made elements, several of which are radioactive.

Key Properties and Trends

• Moving across a period, elements change from metals on the left to non-metals on the right.

• The atomic number of the elements increases by one unit as we move from left to right across a period in the Periodic Table.

• Reactivity of metals decreases while the reactivity of non-metals increases across a period.

• Metals have low ionisation energy (energy required to remove an electron) and non-metals have high ionisation energy.

• There’s an increase in metallic character as one moves down a group, and a decrease in metallic character as one moves from left to right across a period.

Keywords to Remember

• Period: A horizontal row of elements in the Periodic Table.

• Group: A vertical column of elements in the Periodic Table.

• Metal: A substance with high electrical conductivity, luster, and malleability, which readily loses electrons to form positive ions.

• Non-metal: Elements which lack metallic properties and readily gain or share electrons.

• Noble Gases: Elements in Group 0 of the period table. They are all unreactive non-metal gases.

• Transition Metals: Metals in the middle of the period table, between Groups 2 and 3.

Understanding how the Periodic Table is structured will enable you to predict the properties and reactivity of different elements, which is a core skill in many areas of chemistry. Practice using the table to familiarise yourself with its features.