Whole Earth Curriculum WEC

Lesson 06 — Atoms, Elements, Compounds, and Reactions

Learners explain **atoms, elements, and compounds**, and how a **chemical reaction rearranges atoms** — never creating or destroying them — to form new substances. They build water from hydrogen and oxygen and count atoms before and after.

D06 P3: Intellectual & Cognitive Awareness D06.S3 50 minutes Draft

Objectives

Essential question

How do atoms, elements, and compounds rearrange in a chemical reaction to form new substances?

atomelementcompoundmoleculechemical reactionrearrange

Materials

Standard materials

Low-tech / no-cost

Enriched / lab & device

Works in different contexts

A diagram showing two hydrogen atoms and one oxygen atom on the left rearranging into a water molecule on the right, with the note that the same atoms are present before and after, just rearranged
A diagram showing two hydrogen atoms and one oxygen atom on the left rearranging into a water molecule on the right, with the note that the same atoms are present before and after, just rearranged

Lesson 6 — Atoms, Elements, Compounds, and Reactions

Summary

Learners explain atoms, elements, and compounds, and how a chemical reaction rearranges atoms — never creating or destroying them — to form new substances. They build water from hydrogen and oxygen and count atoms before and after.

Objectives

  • Explain atoms, elements, and compounds, and how chemical reactions rearrange atoms to form new substances. (D06.S3.08.01)

Connection

Everything you can touch — water, air, your own hand — is made of tiny pieces called atoms, too small to see. A handful of atoms joined one way makes the water you drink; the very same atoms joined another way make something else entirely. When iron rusts, when a candle burns, when bread bakes, atoms are not being created or destroyed — they are being rearranged. Today you learn to see those invisible rearrangements.

Materials

  • Atom-building sheet
  • Element tiles

Preparation

  • Copy the atom-building sheet and element tiles.
  • Retrieval: from Grade 3 and 6, recall the states of matter and that matter is made of particles too small to see; from Grade 7, recall that matter is reused, not created new.

Facilitator note

This lesson is written to the learner (“you”). The ideas to land: (1) an atom is the smallest piece of an element — with a nucleus of protons and neutrons, and electrons around it; (2) an element is a substance made of one kind of atom, and elements are organized on the periodic table; (3) a compound is a substance made of two or more different elements chemically joined (a molecule is a group of atoms bonded together); (4) in a chemical reaction, atoms are rearranged to form new substances, and no atoms are created or destroyed — that is why the total count is the same before and after. Worked example: hydrogen + oxygen → water (2 H₂ + O₂ → 2 H₂O) — model it with tiles, counting atoms on each side (S-359). The critical-thinking lens: “atoms are conserved” is a checkable fact, not a guess — the same idea as Grade 7’s “matter is reused, not created new.” The technology lens: every material we make — metals, plastics, medicines — is atoms rearranged; the same atoms can become a medicine or a poison depending on how they are joined. The environment lens: reactions like rusting, burning, and photosynthesis are atoms rearranging, and the atoms stay on Earth (S-253). The global lens: the same elements make up every place on Earth — the oxygen in the air of one country is the same element as the oxygen in another. Keep claims precise and cite the atoms/elements/reactions source (S-359); hold the invisible atom as a model with overwhelming evidence, not creed (philosophy §11).

Procedure

  1. Recall (5 min). From Grade 3 and 6: what is matter made of? From Grade 7: what did we mean when we said matter is reused, not created new? Today we meet the atoms that do the reusing.
  2. Meet the atom (10 min). An atom is the smallest piece of an element — a nucleus of protons and neutrons, with electrons around it. An element is a substance made of one kind of atom (like hydrogen, oxygen, carbon). The periodic table lists them all.
  3. Meet compounds (8 min). A compound is made of two or more different elements chemically joined. A molecule is a group of atoms bonded together. Water, H₂O, is a compound: two hydrogens joined to one oxygen.
  4. Watch a reaction (15 min). A chemical reaction rearranges atoms to make new substances. Worked example: hydrogen + oxygen → water. Count the atoms before and after — the same number of each kind, just rearranged. Build it with element tiles.
  5. Build your own (7 min). With a group, build another reaction — carbon + oxygen → carbon dioxide (CO₂) — and count atoms on each side. Same atoms, new substance.
  6. Close (5 min). Share one thing you now know about what happens when something rusts, burns, or bakes. Atoms are rearranged, never made or lost.

Differentiation

  • Support: Provide the reaction pre-built and ask learners to count each kind of atom on both sides.
  • Extension: Balance a reaction with more parts (e.g., two water molecules forming) and explain conservation of atoms in your own words.

Assessment

  • Formative (observation): Can the learner explain atom, element, and compound, and show that a reaction rearranges the same atoms?
  • Portfolio artifact: The completed atom-building sheet, kept in the portfolio.

Home connection

Find something at home that changed — a brown apple, a rusted nail, baked bread — and ask: what atoms were rearranged here?

Resources