Interactive Periodic Table

Click any element to see its atomic number, mass, electron arrangement and an animated atom model. Click a group number or period number to highlight it, switch the colours to see states and trends, or play Find the element to learn the positions.

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How the table is organised

Periods (rows)

There are 7 periods. The period number is the number of electron shells in the atoms of that row. Sodium is in period 3, so it has three shells (2, 8, 1).

Groups (columns)

There are 18 groups. Elements in a group have the same number of outer electrons, so they react in similar ways. For groups 1, 2 and 13 to 18 the outer electrons are 1, 2 and then 3 to 8.

Atomic number

Elements are arranged by atomic number, the number of protons in the nucleus. This is the modern periodic law: the properties of elements repeat in a regular way as the atomic number increases.

Reading an electron configuration

An electron configuration shows how the electrons fill the subshells. For example, sodium is 1s² 2s² 2p⁶ 3s¹: the big number is the shell, the letter is the subshell (s, p, d or f) and the small number is how many electrons it holds. The shorthand [Ne] 3s¹ replaces the filled inner shells with the symbol of the noble gas before the element. The subshells fill in the order 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, ... (4s fills before 3d). Chromium and copper are famous exceptions.

Practise what you learned

Test yourself with chapter-wise MCQs and explanations:

Atomic Structure — Chemistry, HSSC-KPK First Year (1,166 questions)
s and p-Block Elements — Chemistry, HSSC-KPK Second Year (850 questions)
d and f-Block Elements — Chemistry, HSSC-KPK Second Year (819 questions)
Periodic Table and Periodic Properties — Chemistry, HSSC-Punjab First Year (1,439 questions)
Atomic Structure — Chemistry, HSSC-Punjab First Year (960 questions)
Group 2 Elements — Chemistry, HSSC-Punjab Second Year (778 questions)
Periodic Table and Periodicity of Properties — Chemistry, SSC-KPK Class 9 (1,298 questions)
Atomic Structure — Chemistry, SSC-Punjab Class 9 (647 questions)
Periodic Table and Periodicity — Chemistry, SSC-Punjab Class 9 (551 questions)
Group Properties and Elements — Chemistry, SSC-Punjab Class 9 (696 questions)

Atomic masses are IUPAC values rounded for school use; in brackets is the mass number of the longest-lived isotope of an element with no stable isotopes. Electronegativity uses the Pauling scale. Properties of the newest elements (104 to 118) are predicted, not measured. Works offline: after your first visit the table is saved in your browser.