Year 8 Science · Unit 2 · Lesson 20
Apply Worksheet
Learning Goals
Compare two
Complete the table to compare sodium (Na) and chlorine (Cl). Use your unit knowledge to fill in each cell.
| Feature | Sodium (Na) | Chlorine (Cl) |
|---|---|---|
| Metal / non-metal / metalloid? | ||
| Reactivity (high / low / moderate) | ||
| State at room temperature | ||
| Period number | ||
| Group number | ||
| When combined as NaCl, what type of substance is formed? | ||
Predict and reason
Scenario
A student finds an unknown silver-coloured solid on a laboratory bench. It conducts electricity well, can be bent without breaking, and has atomic number 29. The student checks the periodic table and notices it sits in Period 4 in the middle block of the table.
(a) Predict the identity of this element and state which region of the periodic table it belongs to (metal, non-metal, or metalloid area). Justify your prediction using the clues in the scenario.
(b) Predict two uses for this element and justify each use by linking it to a specific property described in the scenario.
1. Sodium (atomic number 11) and potassium (atomic number 19) are both in Group 1. Explain why they have similar chemical properties even though they have different atomic numbers.
2. Carbon-12 and carbon-14 are both forms of carbon. Explain what an isotope is and state what is the same and what is different between these two atoms.
Wrap Up
In one sentence, explain how the position of an element on the periodic table helps scientists predict how it will behave.