Year 8 Science · Unit 2 · Lesson 11

The Periodic Table

Challenge Worksheet

Name

Date

Class

Learning Goals

Design a scientific investigation using the periodic table's predictive power.
Evaluate Mendeleev's decision to leave gaps as a scientific strategy.
Distinguish between correlation (position in table) and measurable properties.

Go Deeper

Design a mini-experiment

A scientist wants to test: "Can the position of an element in the periodic table be used to predict one of its physical properties (e.g. melting point) before measuring it?" Plan the investigation below.

What I will change (independent variable)
What I will keep the same (controlled variables, list 3)
What I will measure (dependent variable)
My prediction (what trend do I expect to see?)
How I would know if my prediction is wrong (falsification condition)
One limitation of this experiment

Show What You Know

1. Mendeleev left gaps in his 1869 table where he predicted undiscovered elements would go. Was this a strength or a weakness of his approach? Use evidence from the history of the periodic table to support your answer.

Challenge 4 marks

2. The modern periodic table arranges elements by atomic number, not atomic mass as Mendeleev did. Explain why this change was necessary and what it reveals about how scientific models are refined over time.

Challenge 3 marks

Wrap Up

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