What is a chemical element?
A chemical element is a substance made of only one kind of atom. Pure iron is made only of iron atoms, and pure gold is made only of gold atoms. At present, 118 elements are known, and all of them are on the periodic table.
"One kind of atom" means atoms with the same number of protons in the nucleus. This number is called the atomic number. An atom with 6 protons is always carbon, and an atom with 8 protons is always oxygen. Atoms with different numbers of neutrons are called isotopes. They have the same number of protons, so they belong to the same element.
The six elements in the simulator:
| Element | Symbol | Atomic number | Latin name |
|---|---|---|---|
| Hydrogen | H | 1 | hydrogenium |
| Carbon | C | 6 | carboneum |
| Oxygen | O | 8 | oxygenium |
| Sodium | Na | 11 | natrium |
| Iron | Fe | 26 | ferrum |
| Copper | Cu | 29 | cuprum |
How are element symbols written?
Every element has a symbol of one or two letters. The first letter is a capital, and the second is lowercase. If you do not follow this rule, the meaning changes: Co is the element cobalt, but CO is carbon monoxide.
Symbols are the same all over the world. Many symbols come from Latin names, so they do not match the English names: Fe comes from the name ferrum, and Cu comes from the name cuprum.
How are elements and compounds different?
A substance made of one kind of atom is an element. A substance made of two or more elements is a compound.
- Oxygen gas, O2, is made of molecules, but both atoms are oxygen, so it is an element.
- Water, H2O, is a compound made of two elements, hydrogen and oxygen.
- Table salt, NaCl, is a compound made of two elements, sodium and chlorine.
See the atoms of elements in the Nalukh chem app
Choose the atoms of six elements and watch them. This simulator unlocks with full access. The app is free to download, and 2 units and 5 simulators are open without signing up.
How do you use the simulator?
- Open the Atoms of elements simulator in the app. Hydrogen is selected at first.
- Press one of the six buttons in the bottom row: H, O, C, Fe, Na, Cu.
- Read the symbol and name of the selected element in the title at the top.
- Watch the atoms inside the frame. Each atom shows the element's symbol, and they are all the same color.
- Press another button and watch all the atoms change at once.
Tasks to try in the simulator
- Press the six buttons in turn and count how many atoms change. Answer: All 28 atoms in the field change at once, and no atoms of another kind remain.
- Sort the six elements into two groups: metals and nonmetals. Answer: Fe, Na, and Cu are metals, and H, O, and C are nonmetals. Check in the Metals and nonmetals article.
- Explain why water is not on this simulator's list. Answer: Water is a compound made of two elements, so it is not an element.
How is the simulator's picture different from real substances?
The simulator shows atoms as round shapes moving freely. This picture helps you understand that all the atoms are one kind. In real substances, atoms are arranged differently:
- Hydrogen and oxygen exist as two-atom molecules, H2 and O2.
- Iron, copper, and sodium atoms line up in an orderly crystal lattice.
- Diamond and graphite, two allotropes of carbon, are both made only of carbon atoms, but their atoms are arranged differently.
