--- title: "What are particles made of?" subtitle: "Year 8 Chemistry · Elements and compounds · Lesson 1" --- # What are particles made of? **Name:** {{field-24}} **Date:** {{field-15}} **Class:** {{field-15}} > **Key question:** 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? :::teacher-note **In one sentence:** 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). **Students should be able to say:** 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. **Width:** the unmarked parts are the floor every student does (Engage, Explore, Explain, Evaluate). Typical and Wider sections add contexts, not difficulty. Students work in the online tutorial alongside this sheet. ::: ## Engage Decide before you look. :::keep-together **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 My prediction, and why: {{lines-3}} ::: :::teacher-note **What happens:** Particles of different kinds. Each is built from atoms, and the atoms come in different types: nitrogen, oxygen, argon, carbon, hydrogen. ::: ## Explore Try it on the board in the tutorial. Was your prediction right? What was different? {{lines-2}} ## Explain: atoms and elements :::keep-together ### 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 ::: :::teacher-note **Answer:** Atoms Every particle is an atom, or atoms joined together. ::: :::keep-together ### 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 ::: :::teacher-note **Answer:** Its atoms are a different type There are about 118 types of atom, one for each element. Atom type decides the element. ::: :::keep-together ### Check your ideas **True or false?** Groups: True, False - All the atoms in a sample of pure oxygen are the same type: {{field-15}} - An element is made of only one type of atom: {{field-15}} - There are about 118 types of atom: {{field-15}} - An oxygen atom in water is a different type from an oxygen atom in air: {{field-15}} - Atoms are coloured like the balls on the board: {{field-15}} - Atoms are the smallest piece of an element that is still that element: {{field-15}} ::: :::teacher-note **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 ::: :::typical ## Elaborate: which gases are elements? :::keep-together ### Single atoms or joined? **How is each element's particle made?** Groups: Single atoms, Two atoms of the same type joined - Helium: {{field-15}} - Neon: {{field-15}} - Oxygen: {{field-15}} - Nitrogen: {{field-15}} ::: :::teacher-note **Answer:** Helium → Single atoms; Neon → Single atoms; Oxygen → Two atoms of the same type joined; Nitrogen → Two atoms of the same type joined ::: :::keep-together ### 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 ::: :::teacher-note **Answer:** Yes: both atoms are the same type One type of atom means an element, however many atoms are in each particle. ::: ::: :::wider ## Elaborate: how the idea of atoms grew :::keep-together **Put the ideas about matter in the order they were proposed, earliest first.** A. `Aristotle: no atoms; everything is earth, water, air and fire, mixed` B. `Dalton: each element has its own type of atom, and atoms join in fixed ratios` C. `Boyle: an element is a substance that cannot be broken down into simpler ones` D. `Democritus: matter is made of tiny pieces that cannot be cut, "atomos"` Correct order (letters): {{field-24}} ::: :::teacher-note **Answer:** see the program below 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. ```science 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 ``` ::: ::: ## 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). ## Exit ticket :::keep-together **What makes gold a different element from silver?** {{lines-3}} ::: :::teacher-note **Answer:** Gold is made of a different type of atom from silver. Atom type decides the element. :::