Everything you can see, touch , taste or breathe is made of atoms — particles so unimaginably small that a single full stop on this page contains many billions of them. Atoms are the fundamental building blocks of all matter in the universe , from your body to distant stars .
✨ A pure substance made of only one type of atom is called an element . There are around 118 known elements , and they are arranged in a famous chart called the periodic table .
📷 SCB2024 · CC0Although atoms are tiny , they have a structure of their own. At the centre is a dense core called the nucleus . Whizzing around the nucleus are even tinier particles called electrons . Most of an atom is actually empty space between the nucleus and the electrons .
The nucleus is made of two kinds of particle . Protons carry a positive electric charge , and neutrons carry no charge at all. The electrons orbiting outside carry a negative charge . In a normal , balanced atom , the number of protons equals the number of electrons , so the charges cancel out.
🃏 Flip each card to learn the parts of an atom.
? Proton A positively charged particle in the nucleus
? Neutron A particle in the nucleus with no charge
? Electron A negatively charged particle orbiting the nucleus
? Nucleus The dense centre of an atom, holding protons and neutrons
Tap each card to see the answer.
💡 The number of protons in an atom is called its atomic number , and it decides which element the atom is. Carbon always has 6 protons ; oxygen always has 8; gold always has 79.
🗂️ Sort each particle by its electric charge.
Positive charge Negative charge No charge
Positive charge Negative charge No charge
Positive charge Negative charge No charge
📷 Ben Mills · Public domainWhen two or more atoms join together , they form a molecule . Atoms join by sharing or swapping their electrons , forming links called bonds . A water molecule is made of two hydrogen atoms bonded to one oxygen atom , which is why water is written as H₂O.
Different combinations of atoms make completely different substances . Carbon dioxide , the gas we breathe out, is one carbon atom joined to two oxygen atoms (CO₂). Ordinary table salt is made of sodium and chlorine atoms joined together . Changing which atoms join , and how many, changes the substance entirely .
🔗 Match each molecule to what it is made of.
Table salt: sodium and chlorine atoms Oxygen gas: two oxygen atoms bonded together Carbon dioxide: one carbon and two oxygen atoms Water: two hydrogen and one oxygen atom
Table salt: sodium and chlorine atoms Oxygen gas: two oxygen atoms bonded together Carbon dioxide: one carbon and two oxygen atoms Water: two hydrogen and one oxygen atom
Table salt: sodium and chlorine atoms Oxygen gas: two oxygen atoms bonded together Carbon dioxide: one carbon and two oxygen atoms Water: two hydrogen and one oxygen atom
Table salt: sodium and chlorine atoms Oxygen gas: two oxygen atoms bonded together Carbon dioxide: one carbon and two oxygen atoms Water: two hydrogen and one oxygen atom
📷 Lexlex · CC BY-SA 4.0The state of matter — solid , liquid or gas — depends on how strongly the atoms or molecules are held together and how much energy they have. In a solid the bonds are strong and the particles only vibrate in place . In a liquid the bonds are looser so particles slide around. In a gas the particles break free and zoom about. So atoms explain the states of matter you met earlier !
✨ The protons in a nucleus all carry the same positive charge , so they should push each other apart . They are held together by an incredibly powerful force , fittingly named the strong nuclear force .
🧩 Order these from the smallest to the largest in scale.
A living cell ? ⤒ ↑ ↓ ⤓
A molecule, such as water ? ⤒ ↑ ↓ ⤓
An atom ? ⤒ ↑ ↓ ⤓
An electron ? ⤒ ↑ ↓ ⤓
✍️ Fill in the atoms and molecules words.
The dense centre of an atom is the _____ , made of protons and _____ . Tiny particles that orbit it are called _____ . When atoms join together they form a _____ .
nucleus neutrons electrons molecule element
