🧪 Interactive Periodic Table of Elements
A periodic table explorer: search any element by name, symbol or atomic number for its atomic weight, group, period and electron configuration.
Reactive nonmetal
14 / 2
p-block
Solid
[He] 2s2 2p2
2, 4
2.55 (Pauling)
1086.5 kJ/mol
Not known
Not known
1.821 g/cm³
Ancient Egypt
All 118 confirmed elements. Atomic masses are the IUPAC standard atomic weights — for elements with no stable isotope, the value is the mass number of the most stable known isotope, which is why it is shown as a whole number. Blank fields are genuine gaps in the measured data rather than zeroes.
What Interactive Periodic Table of Elements Does
The periodic table is ordered by atomic number — the number of protons in the nucleus — and arranged so that elements with similar chemistry fall into the same column. That arrangement was worked out before anyone knew what an electron was, and it holds up because a column shares the same outer-shell electron count, which is what determines how an element reacts.
All 118 confirmed elements are here, with atomic mass, electron configuration, phase, melting and boiling points, density, electronegativity and first ionization energy. Masses are the IUPAC standard atomic weights, which are averages across the isotopes found in nature — that is why chlorine is 35.45 rather than a whole number, and why it is a range rather than a constant for some elements.
For elements with no stable isotope, there is no natural mixture to average, so the convention is to quote the mass number of the most stable known isotope. That is why the bottom of the table reads in whole numbers.
The last stretch of the table is largely predicted rather than measured. Elements past about 104 have been made a few atoms at a time with half-lives in milliseconds, so most of their properties come from extrapolating periodic trends. Where a value is genuinely unknown, this says so rather than showing a zero.
How to Use Interactive Periodic Table of Elements
- Type an element name or symbol in the search input
- Click any element box in the grid to spotlight its properties
- Review atomic mass, orbital electron configuration, and chemical family
Formula Used by Interactive Periodic Table of Elements
How the table is organized
period = the outermost occupied shell · group = the outer-shell electron count · block = the subshell being filled (s, p, d, f)
- atomic number Z
- protons in the nucleus — this defines the element, and the ordering
- standard atomic weight
- the isotope-abundance-weighted average mass, in unified atomic mass units
- electron configuration
- written from the previous noble gas, so iron is [Ar] 3d⁶ 4s²
Worked example
Chlorine, atomic number 17.
- Period 3, group 17 — seven outer electrons, one short of a full shell
- Configuration [Ne] 3s² 3p⁵
- Mass 35.45, because natural chlorine is roughly 76% chlorine-35 and 24% chlorine-37
Result: One electron short of stability, which is why the halogens are so reactive and why chlorine forms a −1 ion.
The categories, and what they share
| Category | Where | Behavior |
|---|---|---|
| Alkali metals | Group 1 | One outer electron, given up eagerly — soft, and violently reactive with water |
| Alkaline earth metals | Group 2 | Two outer electrons; reactive, though less so |
| Transition metals | Groups 3–12 | Filling a d subshell; multiple oxidation states, colored compounds |
| Post-transition metals | Right of the transition block | Softer, lower melting points than transition metals |
| Metalloids | The staircase | Intermediate — the basis of semiconductors |
| Reactive nonmetals | Upper right | Gain or share electrons; the elements of organic chemistry |
| Halogens | Group 17 | One electron short of a full shell, so highly reactive |
| Noble gases | Group 18 | Full outer shell, so almost entirely unreactive |
| Lanthanides | Row below, 57–71 | Filling 4f; chemically very similar to each other |
| Actinides | Row below, 89–103 | Filling 5f; all radioactive |
Trends worth knowing
These are why the shape of the table is useful rather than decorative.
| Property | Across a period | Down a group |
|---|---|---|
| Atomic radius | Decreases — more protons pull the same shell in | Increases — another shell is added |
| Ionization energy | Increases | Decreases |
| Electronegativity | Increases | Decreases |
| Metallic character | Decreases | Increases |
How to Read Your Result
The column tells you the chemistry
Elements in a group share their outer-shell electron count, which is what reacts. Sodium and potassium behave alike because both have one outer electron to lose; fluorine and chlorine behave alike because both are one short of a full shell.
Atomic mass is an average, not a count
Standard atomic weights average over the isotopes found on Earth, weighted by abundance. That is why they are rarely whole numbers, and why IUPAC now publishes intervals rather than single values for a dozen elements whose isotopic composition varies measurably by source.
Missing values are honest gaps
Several superheavy elements have been produced only in single-atom quantities with half-lives too short to measure a melting point. Where a property has never been measured, it is shown as unknown rather than filled in with a prediction.
The f-block is drawn below to save width
The lanthanides and actinides belong between groups 3 and 4. Inserting them inline would make the table 32 columns wide, so convention pulls them out — they are part of periods 6 and 7, not a separate appendix.
Limitations & Accuracy Notes
- Atomic weights are the abridged IUPAC standard values. For elements whose isotopic composition varies by source, IUPAC publishes an interval and this shows a representative value.
- Melting points, boiling points and densities are measured at standard pressure and vary with allotrope — carbon as graphite and as diamond differ substantially.
- Electronegativity is on the Pauling scale, which is not defined for the noble gases and several synthetic elements.
- Properties for elements above roughly 104 are largely predicted rather than measured.
- Isotopes, half-lives and decay chains are outside the scope of this table.
Frequently Asked Questions
What information is provided for each chemical element?
How do I search for a specific element?
How many elements are there?
Why is atomic mass not a whole number?
What does the group and period tell me?
What is an electron configuration notation?
Can I cite this for coursework?
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References & Further Reading
- IUPAC — standard atomic weights — The authority for the atomic masses shown, which were spot-checked against the 2021 abridged values
- Periodic-Table-JSON — The public-domain dataset this table is generated from