On this page
Ask most people to name a metal and they’ll say something like iron, gold, or aluminum without even thinking about it. Ask them to sort all 118 elements into metal, nonmetal, or metalloid, though, and things get a lot less obvious.
Here’s the full breakdown: 91 elements are metals, 20 are nonmetals, and 7 are metalloids — elements that borrow properties from both sides. That three-way split is the broadest way to organize the periodic table. It’s also a bit of a simplification, which is exactly why this site (and most modern chemistry references) breaks things down further into the color-coded categories you’ll see on the interactive table.
Let’s go through all three groups properly.
The 7 metalloids
Metalloids sit along a jagged, staircase-shaped line that runs diagonally from boron down to astatine. On the periodic table, that line marks the boundary between metals to its left and nonmetals to its right — and the seven elements sitting directly on it don’t fit cleanly into either camp.
Here they all are:
Why do these seven earn a whole separate category? Take silicon as the clearest example. It looks metallic — shiny, gray, solid — but it conducts electricity far worse than an actual metal like copper does. That in-between behavior isn’t a flaw. It’s the entire reason silicon runs the semiconductor industry. Engineers can precisely dial silicon’s conductivity up or down by adding tiny amounts of other elements into it, something you simply can’t do with a true metal or a true insulator. Every computer chip on Earth exists because of that one property.
The 20 nonmetals
Nonmetals split into three smaller groups on this site. Here’s every one of the 20, grouped together:
Reactive nonmetals (7 elements): hydrogen, carbon, nitrogen, oxygen, phosphorus, sulfur, and selenium.
Halogens (6 elements): fluorine, chlorine, bromine, iodine, astatine, and tennessine.
Noble gases (7 elements): helium, neon, argon, krypton, xenon, radon, and oganesson.
Nonmetals are basically the mirror image of metals in almost every measurable way. They conduct heat and electricity poorly. In solid form, they’re brittle instead of bendable. Except for graphite, none of them have that shiny metallic look.
Nonmetals only make up a small slice of the periodic table by raw element count, but don’t let that fool you — they dominate the atoms actually inside your own body. Hydrogen, carbon, nitrogen, and oxygen alone make up well over 90% of the atoms in a human being. You are, chemically speaking, mostly nonmetal.
The 91 metals
Metals make up the overwhelming majority of the periodic table, and they split into six separate categories:
- Alkali metals (6 elements): lithium through francium.
- Alkaline earth metals (6 elements): beryllium through radium.
- Transition metals (38 elements): by far the largest category, running from scandium all the way to superheavy elements like copernicium.
- Post-transition metals (11 elements): aluminum, gallium, indium, tin, thallium, lead, bismuth, plus four superheavy elements.
- Lanthanides (15 elements): often called the rare-earth row, running from lanthanum to lutetium.
- Actinides (15 elements): uranium’s row, from actinium to lawrencium.
Metals share a recognizable set of traits: they conduct heat and electricity well, they can be hammered or stretched into new shapes without shattering, and most of them shine when freshly cut or polished. But calling something “a metal” still covers an enormous range of real-world behavior. Sodium is so reactive that it has to be stored underwater or under oil, or it’ll react violently with moisture in the air. Gold, on the other hand, is so unreactive that jewelry made from it thousands of years ago still hasn’t tarnished. Both are, without question, metals — they just sit at opposite ends of what “metal” can mean.
How chemists actually decide the label
You might assume there’s one single test — measure conductivity, check a box, done. There isn’t. Chemists actually look at a whole cluster of properties together, and no single one settles the question on its own.
The usual checklist includes: Does it conduct heat and electricity well? Is it shiny (has “metallic luster”)? Can it be hammered into sheets (malleable) or drawn into wire (ductile) without cracking? Does it tend to lose electrons when it reacts, forming a positive ion, or gain them, forming a negative one? Metals check almost every box on that list. Nonmetals check almost none of them. Metalloids land somewhere in the messy middle, which is exactly why they needed their own category in the first place.
Electronegativity — how strongly an atom pulls on shared electrons in a bond — turns out to be one of the most reliable single numbers for telling the two sides apart, since it’s tied directly to that electron-losing-versus-gaining behavior.
Why the dividing line is fuzzy
Here’s something worth knowing: even the basic metal/metalloid/nonmetal split isn’t fully settled science. A handful of elements sitting right near the staircase line — aluminum, polonium, astatine among them — get classified differently depending on which source you check and which specific properties that source weighs most heavily.
This site follows the category assignments backed by PubChem, our primary data source for every element on this table. Where a genuine disagreement exists in the wider scientific literature about how to classify a borderline element, that disagreement doesn’t get quietly erased or smoothed over. It gets left as it actually is.
Frequently asked questions
Is hydrogen a metal or a nonmetal? Hydrogen is a nonmetal, even though it sits at the top of group 1 on most tables, right above the alkali metals. It shares that position because it has one outer electron, like the alkali metals do, but its actual chemical behavior — existing as a gas, forming covalent bonds far more often than metallic ones — lines up with the nonmetals instead.
Why is carbon a nonmetal if graphite conducts electricity? Graphite is an unusual exception among nonmetals, and it’s specifically why textbooks often call it out by name. Its atoms arrange into flat, stacked sheets that let electrons move freely within each sheet, which is what gives graphite its conductivity. Diamond, made of the exact same carbon atoms arranged differently, doesn’t conduct electricity at all. Same element, dramatically different behavior, based purely on structure.
Do metalloids conduct electricity? Sort of, and that “sort of” is the whole point. Metalloids are called semiconductors precisely because their conductivity sits between a true conductor (metals) and a true insulator (most nonmetals) — and unlike either extreme, that conductivity can often be adjusted with heat, light, or added impurities.
For the full breakdown with colors included, hover over any category in the legend below the interactive table. Or explore one specific property, like electronegativity — one of the clearest numerical signals that separates metals from nonmetals — on its own dedicated trend page.
Advertisement