Periodic Table — Interactive Element Explorer
Click any element to see its atomic number, symbol, name, atomic mass, and category. Filter by element type to highlight groups like noble gases, transition metals, or lanthanides. No signup, runs entirely in your browser.
⏱ 7 min read · Complete guide below
How to Use the Interactive Periodic Table
- 1Click any element to see its atomic number, symbol, name, atomic mass, and category.
- 2Use the category filter to highlight one group — noble gases, halogens, transition metals, and so on.
- 3Read position as information: a period (row) adds an electron shell; a group (column) shares valence electrons.
- 4Trace periodic trends visually across rows and down columns.
Worked Example: Reading Why Sodium Is So Reactive
Click sodium (Na, Z = 11). It sits in Group 1, the alkali metals, on the far left of period 3. Group 1 tells you it has a single valence electron, and being low in the group means that electron is far from the nucleus and loosely held. That is the whole story of sodium's violent reaction with water: it readily gives up that one electron to form Na⁺. Highlight the Group 1 filter and you see the same pattern intensify downward — potassium reacts harder than sodium, caesium harder still.
Now jump to the opposite corner and click a noble gas like neon (Ne, Z = 10) in Group 18. Its outer shell is full, so it has almost no tendency to react — the reason neon glows harmlessly in signs while sodium must be stored under oil. The table's layout is the explanation: reactivity, atomic radius, and ionisation energy all trend predictably by position, so knowing where an element sits tells you how it behaves before you look up a single reaction.
Why the Table Is Shaped the Way It Is
The periodic table looks like an odd staircase, but every part of its shape encodes chemistry. Elements are arranged in order of increasing atomic number (the number of protons), and the rows and columns are aligned so that elements with similar properties fall into the same vertical column. That arrangement is not arbitrary — it mirrors how electrons fill up around the nucleus. Each horizontal period corresponds to a new electron shell being filled, and each vertical groupgathers elements that share the same number of outer (valence) electrons. Because an element's chemistry is governed largely by its valence electrons, elements in the same group behave alike, which is exactly what makes the table so predictive.
Reading Periodic Trends
The real power of the table is that properties change in smooth, predictable trends across it, so position tells you behaviour. Atomic radius generally increases as you go down a group (more shells) and decreases across a period (a stronger nuclear pull draws electrons in). Ionisation energy and electronegativity do the opposite, rising toward the top right. Metallic character increases toward the bottom left. These trends explain the worked example above — why reactive metals cluster on the left and unreactive noble gases sit on the far right — and they turn the table from a lookup chart into a reasoning tool: once you know where an element is, you can estimate how it will behave without memorising each one individually.
Metals, Nonmetals, and the Categories
The colour coding groups elements into families that behave in broadly similar ways. On the left and centre are the metals — including the highly reactive alkali and alkaline earth metals, the familiar transition metals like iron and copper, and the post-transition metals — which tend to lose electrons and conduct heat and electricity. On the right are the nonmetals, including the reactive halogens and the inert noble gases, which tend to gain or share electrons. Straddling the dividing line are the metalloids, which show a mix of both behaviours and are vital in semiconductors. The two detached rows at the bottom, the lanthanides and actinides, are f-block elements pulled out for space but belonging in periods 6 and 7. Filtering by any of these categories is a fast way to study one family at a time.
Periodic Table Tips
Use the category filter
Click any category button above the table to dim all other elements and highlight the group you are studying. Noble gases, halogens, and alkali metals are common exam questions.
Periodic trends
Atomic radius increases down a group and decreases left to right across a period. Electronegativity and ionisation energy show the opposite trend. These trends are visible directly in the table layout.
Memorise key elements
Focus on elements 1-20 for most school exams. The symbols for transition metals (Fe=Iron, Cu=Copper, Ag=Silver, Au=Gold, Hg=Mercury) are the most commonly confused because they come from Latin names.
f-block rows
Lanthanides and actinides are placed below the main table for space, but they belong in periods 6 and 7. La (Z=57) and Ac (Z=89) mark where each f-block row connects back to the main table.
Frequently Asked Questions
How many elements are in the periodic table?
The modern periodic table contains 118 confirmed elements, from Hydrogen (Z=1) to Oganesson (Z=118). Elements 1-94 occur naturally; elements 95-118 are synthetic (produced in laboratories).
What do the colours represent?
Elements are colour-coded by category: alkali metals, alkaline earth metals, transition metals, post-transition metals, metalloids, reactive nonmetals, halogens, noble gases, lanthanides, and actinides. Use the "Highlight" filter to isolate any category.
What is atomic mass?
Atomic mass (shown in atomic mass units, u) is the weighted average mass of all naturally occurring isotopes of an element. For synthetic elements, the mass shown is the most stable isotope (no stable isotopes exist for these elements).
What are lanthanides and actinides?
Lanthanides (La to Lu, Z=57-71) are the f-block elements in period 6. Actinides (Ac to Lr, Z=89-103) are the f-block elements in period 7. They are placed in separate rows below the main table because their chemical behaviour differs from the d-block transition metals.
What is a period and a group?
A period is a horizontal row in the periodic table — each period adds one electron shell. A group (or family) is a vertical column — elements in the same group have the same number of valence electrons and similar chemical properties.
Is my data stored?
No. The periodic table is fully static data loaded in your browser. No information is sent to any server.
Why are elements arranged the way they are in the periodic table?
Elements are ordered by increasing atomic number (proton count), and the rows and columns are aligned so that elements with similar chemical behaviour fall into the same vertical group. This structure reflects how electrons fill up around the nucleus: each period represents a new electron shell, and each group shares the same number of outer (valence) electrons. Because valence electrons largely determine chemistry, elements in a group behave alike — which is why the arrangement is so useful.
What are periodic trends and how do I read them?
Periodic trends are the predictable ways properties change across the table. Atomic radius increases down a group and decreases across a period; ionisation energy and electronegativity increase toward the top right; metallic and reactive character increases toward the bottom left for metals. Because these trends follow position, you can estimate how an element behaves just from where it sits — a powerful shortcut that turns the table into a reasoning tool rather than a lookup chart.
What is the difference between a group and a period?
A period is a horizontal row and a group is a vertical column. Moving across a period, each element adds one proton and one electron, filling the same electron shell, so properties shift gradually. Moving down a group, elements gain whole new shells but keep the same number of valence electrons, which is why they share similar chemical properties. Groups are sometimes called families for this reason — the alkali metals and the noble gases are both groups.
Why are lanthanides and actinides shown separately below the table?
They actually belong within periods 6 and 7 as the f-block elements, but including them in the main body would make the table impractically wide. To save space they are pulled out into two rows beneath it. Lanthanum (element 57) marks where the lanthanides connect back into period 6, and actinium (element 89) where the actinides connect into period 7. Their separation is purely a layout convenience, not a difference in status.
Which elements should I focus on for chemistry exams?
For most school-level chemistry, the first 20 elements (hydrogen through calcium) cover the vast majority of questions, since they illustrate the key groups and trends. Beyond those, it helps to learn the symbols of common transition metals whose abbreviations come from Latin and are easily confused — such as Fe (iron), Cu (copper), Ag (silver), Au (gold), and Hg (mercury). Using the category filter to study one group at a time is an efficient way to revise.