Interactive Periodic Table

All 118 elements in one colourful table — tap any element to see its electronic configuration, K-L-M-N shells, valency, Bohr model, uses and a fun fact, then test yourself with the quiz.

Class 8–12 Science · Chemistry 118 elements Quiz mode
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Hover to highlight a group and period Arrow keys move between elements · Enter opens details Press Enter in search to open the first match
Learn the table

How to read the periodic table

The modern periodic table arranges elements in order of increasing atomic number into 18 vertical groups and 7 horizontal periods. Elements in the same group behave alike because they have the same number of valence electrons.

Hover or tap an element

Its group and period light up and a quick summary appears in the middle of the table.

Filter and search

Show only one category, block or state, or colour the table by electronegativity to spot trends.

Open the detail card

See the Bohr model, configuration, K-L-M-N shells, valency, neutrons, uses and a fun fact.

Quiz yourself

Symbols, names and groups — 10 quick questions with a review of every answer.

Reading an element tile

Atomic number (Z) = number of protons = number of electrons in a neutral atom. Mass number (A) = protons + neutrons.

Neutrons = A − Z

Sodium: Z = 11, A = 23 → 23 − 11 = 12 neutrons. The atomic mass on each tile (22.990 u) is the average over all natural isotopes.

Shells and valency

A shell can hold at most 2n² electrons: K = 2, L = 8, M = 18, N = 32. The outermost shell holds at most 8 (the octet).

Valency = valence e⁻ (1–4) or 8 − valence e⁻ (5–8)

Chlorine 2, 8, 7 → 8 − 7 = valency 1. Magnesium 2, 8, 2 → valency 2.

Periodic trends

  • Across a period (left → right): atomic size decreases, metallic character decreases, electronegativity increases.
  • Down a group: atomic size increases, metallic character increases, electronegativity decreases.
  • Fluorine (3.98) is the most electronegative element; caesium and francium are the least.

s, p, d and f blocks

The block tells you which subshell receives the last electron: s (groups 1–2 and He), p (groups 13–18), d (groups 3–12, transition metals) and f (lanthanoids and actinoids).

Following the NCERT table, lanthanum (57) and actinium (89) sit in group 3; the 14 elements after each form the separate f-block rows.

Did you know? Mendeleev left gaps in his 1869 table and predicted “eka-aluminium” and “eka-silicon”. When gallium (1875) and germanium (1886) were discovered, their properties matched his predictions. Today’s Modern Periodic Law (Moseley) says properties are a periodic function of atomic number, not atomic mass.