These questions revise the lessons in the periodic table section. Use proton numbers: Li 3, Na 11, K 19, Mg 12, Ca 20, Cl 17, S 16, Ar 18.
Try each question on paper before opening the answer.
Questions
Question 1
An element has electron arrangement 2.8.6. State its group, its period and its name.
Answer
Three shells, so period 3. Six outer electrons, so group 10 + 6 = group 16. Proton number 16 gives sulfur.
Question 2
An element is in group 2 and period 4. Write its electron arrangement.
Answer
Period 4 means four shells, and group 2 means two outer electrons. The arrangement is 2.8.8.2, which is calcium.
Question 3
Explain why a magnesium atom is smaller than a sodium atom.
Answer
Both have three shells. Magnesium has 12 protons and sodium has 11, so the nuclear attraction on the outer electrons is stronger in magnesium. The electrons are pulled closer, so the atom is smaller.
Question 4
Metal X fizzes very slowly in water, metal Y melts and the gas ignites, and metal Z fizzes quickly without a flame. Put them in order of reactivity, with evidence.
Answer
Y is most reactive because it melts and the gas ignites, showing the most heat released. Z fizzes quickly without a flame, and X fizzes very slowly. Order: Y, then Z, then X.
Question 5
Rubidium is below potassium in group 1. Predict how it reacts with water, and write the equation.
Answer
Rubidium reacts more vigorously than potassium, because its outer electron is further from the nucleus. Products are rubidium hydroxide and hydrogen.
Equation: 2Rb + 2H₂O → 2RbOH + H₂.
Question 6
Chlorine water is added to potassium iodide solution. State the observation and write the equation.
Answer
Chlorine is more reactive than iodine, so it displaces iodine. The colourless solution turns brown.
Equation: Cl₂ + 2KI → 2KCl + I₂.
Question 7
Explain why argon does not react with other elements.
Answer
Argon has the arrangement 2.8.8, so its outer shell is full. It has no tendency to lose, gain or share electrons. That is why it is unreactive.
Question 8
An element with arrangement 2.8.1 reacts with an element with arrangement 2.8.7. Name the compound and state the type of bond.
Answer
2.8.1 is sodium and 2.8.7 is chlorine. Sodium loses one electron to form Na⁺, and chlorine gains one to form Cl⁻. The compound is sodium chloride, with an ionic bond.
If you got these wrong
- Questions 1 and 2: revise electron arrangement, group and period.
- Questions 3 and 7: revise explaining trends using atomic structure.
- Questions 4 and 6: revise comparing selected groups using evidence.
- Questions 5 and 8: revise predicting simple reactions from periodic position.
Log the step that failed in the mistake log and paper error review, or set a timed round with the timed original practice session builder. If explanations stay weak, see online one-to-one Chemistry tuition.