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.
The modern periodic table arranges all 118 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: every halogen in group 17 has 7 valence electrons, so each has a valency of 1.
All elements
Click a column to sort · click a row for full details.
| Configuration | Shells |
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Quiz settings
10 questions per round · use keys 1–4 and Enter.
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.
Interactive Periodic Table — your questions
How many elements are in the periodic table?
There are 118 elements in the modern periodic table, from hydrogen (atomic number 1) to oganesson (atomic number 118). Of these, 94 occur naturally on Earth and the rest are synthetic, made in laboratories. They are arranged in 18 groups and 7 periods, and split into the s, p, d and f blocks.
What is the difference between a group and a period?
A group is a vertical column and a period is a horizontal row. Elements in the same group have the same number of valence electrons, so they show similar chemical behaviour — all group 1 metals react with water. Elements in the same period have the same number of electron shells but very different properties.
How do you find the valency of an element from the periodic table?
Write the electronic configuration and look at the outermost shell. If it has 1 to 4 electrons the valency equals that number; if it has 5 to 8, valency is 8 minus that number. Chlorine is 2, 8, 7 so its valency is 8 − 7 = 1. Magnesium is 2, 8, 2 so its valency is 2.
Why is the modern periodic table based on atomic number?
Mendeleev arranged elements by atomic mass, which left a few pairs such as cobalt and nickel in the wrong order. Moseley's work on X-ray spectra showed that atomic number, not mass, is the fundamental property. The Modern Periodic Law therefore states that the properties of elements are a periodic function of their atomic number.
What are s, p, d and f block elements?
The block tells you which subshell receives the last electron. The s-block is groups 1 and 2 plus helium, the p-block is groups 13 to 18, the d-block is groups 3 to 12 (the transition metals), and the f-block holds the lanthanoids and actinoids placed in two separate rows below the main table.
How do atomic size and electronegativity change in the periodic table?
Going left to right across a period, atomic size decreases, metallic character decreases and electronegativity increases, because the nuclear charge grows while the shell stays the same. Going down a group, atomic size increases, metallic character increases and electronegativity decreases. Fluorine, at 3.98, is the most electronegative element of all.
How do I remember the periodic table easily?
Learn the first 20 elements in order first, then add the common transition metals. Group-by-group mnemonics help more than trying to memorise the whole table at once, because elements in one group share properties. Using the quiz on this page in short daily rounds — symbols, names and groups — works far better than one long session.