Year 9 Science · Unit 2 · Lesson 07
Challenge Worksheet
Learning Goals
Explain it simply
Explain why metals form positive ions and non-metals form negative ions to a student who finds this confusing. Use the sentence starters below. You can include examples from the lesson.
"Metals tend to be on the left side of the periodic table, where atoms have..."
"It is 'easier' for a metal to lose a few electrons because..."
"Non-metals, on the right side, have outer shells that are nearly full, so they..."
"The result is that when metals and non-metals react..."
1. Iron can form Fe²⁺ or Fe³⁺ ions. Using the simplified electron configuration for iron (2,8,14,2), explain why iron has more than one possible valency, unlike sodium which only ever forms Na⁺.
2. The Australian Institute of Marine Science studies ionic compounds dissolved in seawater around the Great Barrier Reef. Seawater contains Na⁺, Cl⁻, Mg²⁺, and SO₄²⁻ ions. A student claims: "All ions in seawater must have come from metals losing electrons." Evaluate this claim. Is it fully correct? Use your knowledge of anion formation to support your answer.
Wrap Up
In one sentence, what was the main idea of this lesson?