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# What are particles made of?

Year 8 Chemistry · Elements and compounds

<!-- Speaker note: Students extend the particle model so that particles are atoms with a type, and explain that atom type decides the element (AC9S8U06, node 1, a hinge node). About 20 minutes (Engage and Explore 6 min · Explain 8 min · Evaluate 3 min · Typical adds 5 min, Wider about 4 min). -->

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## Today

**We are learning to** the particles of the particle model are atoms. Atoms come in different types, one type for each element, and atom type decides what element a substance is.

- I can explain that the particles in the particle model are atoms.
- I can explain that different elements are made of different types of atom.
- I can explain that atom type decides what element a substance is.

<!-- Speaker note: Before class: A concept tutorial for introducing or revising the idea; it does not replace models, kits or class discussion. Set the width with `?width=minimum`, `typical` (default) or `wider`. Frame it as an upgrade, not a replacement: "you know particles exist; now we add that particles have a type". The hinge risk is students carrying identical particles into compounds (node 3) and chemical change. Teacher: In your own words: collect the sentence; it is the node's checkpoint in the student's words. -->

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## Why it matters

> Water, oxygen and carbon dioxide are all made of particles. So why is one a drink, one keeps you alive, and one puts out fires?

<!-- Speaker note: In Year 7 every particle was just "a particle". This lesson gives them an identity. -->

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<span style="background:#dbeafe; color:#1a1a1a; border:1.5px solid #3b82f6; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">💬 Discussion</span>

## Engage: predict

**Air is a mixture of gases. If you could zoom in far enough, what would you see?**

- Particles floating in a little bit of air
- Identical particles, because it's all air
- One continuous substance with no particles
- Particles of different kinds, built from smaller pieces of different types

<!-- Speaker note: What happens: Particles of different kinds. Each is built from atoms, and the atoms come in different types: nitrogen, oxygen, argon, carbon, hydrogen. Take two or three predictions before anyone runs it. -->

<!-- Speaker note: Teacher: count how many chose identical particles. That is the Year 7 picture the board upgrades. -->

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<span style="background:#fef3c7; color:#1a1a1a; border:1.5px solid #f59e0b; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✍️ Activity</span>

## Explore it

{{embed: https://studio.learningwaypoints.com/tutorials/_playground-science/index.html?id=deck%2Fscience%2Fchemistry-8%2Fatoms%2Fstep-2&code=widget%3A+atoms%0Ashow%3A+N2+x8%2C+O2+x3%2C+Ar+x1%2C+CO2+x1%2C+H2O+x2%0Acaption%3A+A+tiny+sample+of+air%2C+enlarged+millions+of+times.%0A}}

[Open this step in the tutorial](https://studio.learningwaypoints.com/tutorials/science/chemistry-8/atoms/?full=step-2#step-2)

<!-- Speaker note: Click a particle (or press **Inspect next particle**) to see what it is made of. Find every kind. Notice the coloured balls: each colour is one **type of atom**. -->

<!-- Speaker note: Teacher: students should find all five kinds in air (nitrogen, oxygen, argon, carbon dioxide, water). Ask which colours appear in more than one kind of particle. -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## What happened?

* Particles of different kinds. Each is built from atoms, and the atoms come in different types: nitrogen, oxygen, argon, carbon, hydrogen.

<!-- Speaker note: Reveal after running. Ask who predicted it, and what made them think so. -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## Particles are atoms

**In the Year 7 particle model, everything is made of particles. What are those particles made of?**

- Air
- Cells
- Atoms
- Smaller bits of the same substance, all the way down

* Answer: Atoms

<!-- Speaker note: Every particle is an atom, or atoms joined together. -->

<!-- Speaker note: Teacher: the two questions carry the checkpoint. The sort catches 'atoms have colours' and 'oxygen in water is different'. -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## Atom type

**What makes oxygen a different element from nitrogen?**

- Its atoms are a different type
- It has more atoms
- It is a different colour
- Its atoms are bigger

* Answer: Its atoms are a different type

<!-- Speaker note: There are about 118 types of atom, one for each element. Atom type decides the element. -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## Check your ideas

**True or false?**

Groups: True · False

All the atoms in a sample of pure oxygen are the same type · An element is made of only one type of atom · There are about 118 types of atom · An oxygen atom in water is a different type from an oxygen atom in air · Atoms are coloured like the balls on the board · Atoms are the smallest piece of an element that is still that element

* Answer: All the atoms in a sample of pure oxygen are the same type → True; An element is made of only one type of atom → True; There are about 118 types of atom → True; An oxygen atom in water is a different type from an oxygen atom in air → False; Atoms are coloured like the balls on the board → False; Atoms are the smallest piece of an element that is still that element → True

<!-- Speaker note:  -->

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<span style="background:#fef3c7; color:#1a1a1a; border:1.5px solid #f59e0b; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✍️ Activity</span>

## Elaborate: which gases are elements?

{{embed: https://studio.learningwaypoints.com/tutorials/_playground-science/index.html?id=deck%2Fscience%2Fchemistry-8%2Fatoms%2Fstep-4&code=widget%3A+atoms%0Ashow%3A+He+x5%2C+Ne+x5%2C+O2+x4%2C+N2+x4%0Aneed%3A+all%0Acaption%3A+Four+gases.+Which+are+elements%3F%0A}}

[Open this step in the tutorial](https://studio.learningwaypoints.com/tutorials/science/chemistry-8/atoms/?full=step-4#step-4)

<!-- Speaker note: What this step is for: Single atoms and two-atom molecules can both be elements: the test is one atom type, not one atom. -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## Single atoms or joined?

**How is each element's particle made?**

Groups: Single atoms · Two atoms of the same type joined

Helium · Neon · Oxygen · Nitrogen

* Answer: Helium → Single atoms; Neon → Single atoms; Oxygen → Two atoms of the same type joined; Nitrogen → Two atoms of the same type joined

<!-- Speaker note:  -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## One type, two atoms

**An oxygen particle (O₂) has two atoms. Is oxygen still an element?**

- No: two atoms joined make a compound
- Yes: both atoms are the same type

* Answer: Yes: both atoms are the same type

<!-- Speaker note: One type of atom means an element, however many atoms are in each particle. -->

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## Elaborate: how the idea of atoms grew

**Put the ideas about matter in the order they were proposed, earliest first.**

```science
Aristotle: no atoms; everything is earth, water, air and fire, mixed
Dalton: each element has its own type of atom, and atoms join in fixed ratios
Boyle: an element is a substance that cannot be broken down into simpler ones
Democritus: matter is made of tiny pieces that cannot be cut, "atomos"
```

<!-- Speaker note: Democritus (about 400 BCE): atoms as an idea without evidence. Aristotle (about 350 BCE): his four elements won for 2000 years. Boyle (1661): elements defined by experiment. Dalton (1808): atoms explain why elements combine in fixed ratios. In Year 9 the model changes again: atoms have smaller parts inside. Correct order: Democritus: matter is made of tiny pieces that cannot be cut, "atomos" Aristotle: no atoms; everything is earth, water, air and fire, mixed Boyle: an element is a substance that cannot be broken down into simpler ones Dalton: each element has its own type of atom, and atoms join in fixed ratios What this step is for: Ordering the models shows the atom as a model refined by evidence, which prepares Year 9 (atoms have parts inside). -->

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## Evaluate: look back

What did you think air was made of? Write one sentence: "At first I thought… Now I think… because…"

**Revision summary**

- The particles in the particle model are **atoms** (or atoms joined together).
- There are about 118 **types of atom**, one for each **element**.
- All atoms of one element are the same type. **Atom type decides the element.**
- An element can be single atoms (helium) or atoms of one type joined (oxygen, O₂).

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<span style="background:#dcfce7; color:#1a1a1a; border:1.5px solid #22c55e; padding:6px 18px; border-radius:8px; font-size:1em; font-weight:500;">✅ Check</span>

## Exit ticket

**What makes gold a different element from silver?**

* Gold is made of a different type of atom from silver. Atom type decides the element.

<!-- Speaker note: Students answer on paper or a mini whiteboard before the reveal. Anyone who cannot answer needs the main idea again next lesson. Where this leads: Next: node 3, compounds (different atom types chemically joined), with the formula notation that goes with them. In class: ball-and-stick or modelling-clay atoms in different colours; build O₂, N₂, H₂O and CO₂ and sort them into elements and compounds. -->