Year 7 Science · Unit 2 · Lesson 11

Evidence for Chemical Change

Foundation Worksheet

Name
Date
Class

Learning Goals

Warm Up

Match each term to its description

Write the matching letter next to each sign of chemical change on the left. Definitions are shuffled — they do not match row order.

Sign of chemical changeYour answerDescription
Colour changeA. A solid substance suddenly appears when two clear liquids are mixed together.
Gas producedB. The mixture or substance gets noticeably hotter or colder without being heated.
Precipitate formsC. Sparks, a flash, or a loud bang occurs during the change.
Temperature changeD. Bubbles form because a brand-new gaseous substance is being made.
Light or sound producedE. A substance turns a noticeably different colour, such as iron going orange.
EvidenceF. Observations that support (but don't always prove) a scientific claim.

Your Turn

Sort it!

Each observation below is evidence of one of the five signs of chemical change. Write each item in the correct category box. Some signs may have more than one item.

Iron nail turns rusty orange Vinegar + bicarb soda fizzes Two clear liquids mix and go cloudy Hand warmer heats up on its own Burning magnesium gives a bright white flash CO₂ bubbles out when acid hits limestone Fireworks bang and explode Copper turns green on an old roof Yellow solid forms in a clear solution Steel wool + vinegar gets warm

Colour change

Gas produced

Precipitate forms

Temperature change

Light or sound

Show What You Know

1. A student heats a piece of steel wool. It glows orange and crumbles into a dark powder. Name TWO signs of chemical change visible in this observation.

Recall 2 marks

2. Why do scientists say the five signs are "evidence" of chemical change rather than "proof"? Give an example of a sign that could also appear in a physical change.

Recall 2 marks

Wrap Up

In one sentence, what was the main idea of this lesson?

HSCScience · Year 7 Science · Unit 2 · Lesson 11 · Foundation Worksheet