LearnLearn Guide for parents
What is the periodic table? A simple explanation for kids
The periodic table is a chart of every element, the basic ingredients that everything in the universe is made of. It lists all 118 known elements in order of their atomic number, and it puts elements that behave alike in the same column, so the chart works like a map of how matter behaves.
This is the explanation I give my own kids, in the order I'd give it. It's written so a parent can read it aloud or an older kid can read it alone.
What is an element?
An element is a substance made of only one kind of atom. Atoms are far too small to see, and everything you can touch is made of them. Gold is made of gold atoms only. Oxygen is made of oxygen atoms only.
Most things are not pure elements. They're elements joined together. Water is hydrogen and oxygen. Table salt is sodium and chlorine. The periodic table lists the ingredients, and almost everything around us is a recipe made from them.
What do the numbers on the periodic table mean?
The big number on each square is the atomic number. It counts the protons, the tiny particles in the center of every atom of that element. Every element has its own number, and no two share one.
- Hydrogen has 1 proton, so it's number 1.
- Helium has 2, so it's number 2.
- Carbon has 6, so it's number 6.
The table is in order of that number, from 1 to 118, reading left to right and top to bottom like a book. The one or two letters on each square are the element's symbol, a short name used all over the world. Some symbols come from old Latin names, which is why sodium is Na (from *natrium*) and potassium is K (from *kalium*) (Britannica, Britannica).
How are the rows and columns arranged?
The table has 7 rows, called periods, and 18 columns, called groups (Britannica). Each new row starts a new layer of electrons around the atom, so atoms tend to get bigger as you go down.
The columns are the clever part. Elements in the same column usually act alike:
| Column | Family name | What they're like | Examples |
|---|---|---|---|
| Group 1 | Alkali metals | Soft, shiny metals that react fast with water | Lithium, Sodium, Potassium |
| Group 2 | Alkaline earth metals | Reactive metals, calmer than group 1 | Magnesium, Calcium |
| Group 17 | Halogens | Make salts with metals | Fluorine, Chlorine |
| Group 18 | Noble gases | Gases that very rarely react | Helium, Neon, Argon |
The two rows printed under the main table, the lanthanides and actinides, really belong inside rows 6 and 7. They're pulled out only so the chart fits on a page.
Are most elements metals?
Yes. Most elements are metals, and they fill the left side and middle of the table. Nonmetals sit at the top right, and a zigzag of metalloids, elements with a bit of both, runs between them (Britannica).
At room temperature, most elements are solids. Only two are liquids, mercury and bromine, and eleven are gases, including hydrogen, oxygen, nitrogen and all the noble gases that occur in nature (Britannica).
Who made the periodic table?
The Russian chemist Dmitri Mendeleev published the first version of the modern periodic table in 1869 (Britannica). He lined up the elements known at the time by weight and noticed that their behavior repeated in a pattern. That repeating pattern is why it's called *periodic*.
His boldest move was leaving gaps. Mendeleev said some elements hadn't been discovered yet and predicted what they would be like. Gallium was found in 1875 and germanium in 1886, and both fit his predictions closely (Britannica). The table grew from there. The last four elements, nihonium, moscovium, tennessine and oganesson, got their official names in 2016, which completed the seventh row (IUPAC).
How can kids learn the periodic table?
Kids learn it best by meeting a few elements at a time, through things they can touch and games they want to play, instead of memorizing all 118 in order. I wrote a separate step-by-step plan for teaching kids the periodic table.
That's also why I made Elemon, a free periodic table card game where every element is a monster card and every move is a real fact. The card colors follow the real families above; here's how the nine types line up. A good place to start is the first 20 elements in the Elemondex, from hydrogen to calcium.
Frequently asked questions
How many elements are on the periodic table?
- Elements 1 to 118 have all been discovered or made and officially named. The last four were named in 2016.
What is the first element on the periodic table?
Hydrogen, element number 1. It has one proton, and it is the lightest element.
Why is it called the periodic table?
Because the elements' properties repeat in a regular pattern, or period, as the atomic number goes up. Elements with similar behavior end up in the same column.
What age should kids learn the periodic table?
Kids usually study it properly in middle and high school science, but younger kids can start with names and everyday examples long before that, especially through games.
Ready to meet the elements? Pull up a table and play, or browse all 118 cards in the Elemondex.