Chemistry A Level

Periodic Table

When studying for A Level Chemistry, you will need to be familiar with the Periodic Table. You will use the Periodic Table often throughout the A Level Chemistry course. Have a copy of the Periodic Table handy so you can refer to it often while learning about chemical elements.

The periodic table of the chemical elements is a tabular display of the 118 known chemical elements organized by selected properties of their atomic structures. Elements are presented by increasing atomic number, the number of protons in an atom's atomic nucleus. While rectangular in general outline, gaps are included in the horizontal rows (known as periods) as needed to keep elements with similar properties together in vertical columns (known as groups), such as alkali metals, alkali earths, halogens, noble gases.

Chemistry A Level Periodic Table

Who invented the Periodic Table?

Although there were precursors, the current presentation's invention is generally credited to Russian chemist Dmitri Mendeleev (Mendeleef), who developed a version of the now-familiar tabular presentation in 1869 to illustrate recurring ("periodic") trends in the properties of the then-known elements. The layout of the table has been refined and extended over time, as new elements have been discovered, and new theoretical models have been developed to explain chemical behavior.


The vertical columns of the Periodic Table are called Groups. Groups are considered the most important method of classifying the elements. In some groups, the elements have very similar properties and exhibit a clear trend in properties down the group. Under the international naming system, the groups are numbered numerically 1 through 18 from the left most column (the alkali metals) to the right most column (the noble gases


The horizontal rows in the Periodic Table are called Periods. Although groups are the most common way of classifying elements, there are some regions of the periodic table where the horizontal trends and similarities in properties are more significant than vertical group trends.

To excel at A Level Chemistry, you need to be thoroughly familiar with the Periodic Table.