Year 8 Science · Unit 2 · Lesson 10

Comparing Atomic Models

Foundation Worksheet

Name

Date

Class

Learning Goals

Name the four main atomic models in chronological order
Identify what each model shows and its key limitation
Explain why models get replaced when new evidence arrives

Warm Up

Odd one out

Circle the item that does not belong in each group. Then write the odd one and the reason it doesn't fit in the Answer column.

#	Group	Odd one out + reason
1	Solid sphere Plum pudding Nuclear model Crystal lattice
2	Explains electrons in rings Explains spectral lines Explains why gold foil deflects Explains quarks inside protons
3	New evidence arrived Technology improved Previous model made wrong predictions A scientist felt like changing it

Your Turn

Fill the gap

Choose the correct word from the word bank to complete the passage below. Each word is used once.

evidence electrons nucleus shells Rutherford Thomson Bohr compound proton

Atomic models have changed over time as new was gathered. John Dalton proposed the first model, a solid sphere with no internal structure. J.J. then discovered that atoms contain , creating the plum-pudding model. Ernest fired alpha particles at gold foil and found that most passed straight through, but a few bounced back, revealing a tiny dense at the centre of the atom. Finally, Niels refined this picture by showing that electrons orbit in fixed energy levels called .

Show What You Know

1. Name the four main atomic models in the order they were proposed and state one thing each model shows that the previous one did not.

Recall 2 marks

2. Why do scientists replace an atomic model even when it is still useful? Use the word evidence in your answer.

Recall 2 marks

Wrap Up

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