The Periodic Table — Drills · Grade 8 Science

Chapter: Properties of Matter

What these drills covers

By the end of The Periodic Table you should be able to:

8 questions, multiple choice, numeric and written answer, each with a worked explanation.

Vocabulary used: periodic table, period, group (family), valence electron, metalloid, model, evidence, system boundary, assumption.

Problem 1

Elements in the same column of the periodic table generally have
  1. the same mass
  2. similar chemical behaviour
  3. the same number of neutrons
  4. identical melting points
Answer and explanation

similar chemical behaviour

A column shares the same number of outer electrons, which is what governs how an element reacts.

Problem 2

An element has atomic number 12. How many protons does one of its atoms contain?
Answer and explanation

12

Atomic number is the proton count.

Problem 3

Moving left to right across a period, the atomic number
  1. decreases
  2. stays the same
  3. increases by one each time
  4. doubles
Answer and explanation

increases by one each time

The table is ordered by increasing atomic number.

Problem 4

Which group is least likely to react with anything?
  1. Alkali metals
  2. Halogens
  3. Noble gases
  4. Transition metals
Answer and explanation

Noble gases

Noble gases have full outer electron shells, so they have little tendency to gain, lose or share electrons.

Problem 5

Sodium has atomic number 11 and chlorine 17. How many more protons does a chlorine atom have?
Answer and explanation

6

17 − 11 = 6.

Problem 6

Metals are generally found
  1. on the right of the table
  2. on the left and centre
  3. only in the top row
  4. only among the noble gases
Answer and explanation

on the left and centre

Metals occupy the left and centre; non-metals sit at the upper right, with metalloids along the dividing line.

Problem 7

Why did arranging elements by their properties let gaps in the table be predicted before the missing elements were found?
Answer and explanation

Because the arrangement is periodic: elements with similar behaviour recur at regular intervals, so a gap in a column meant an undiscovered element should exist with properties between its neighbours. That allowed predictions of mass and behaviour specific enough to be checked when the element was later isolated, which is what made the table more than a filing system.

Response criteria

  • State a scientifically accurate conclusion.
  • Show the data, mechanism, or calculation that supports it.
  • Include units, conditions, or limits where relevant.

Problem 8

Lithium, sodium and potassium all react vigorously with water. Explain what they share that accounts for this.
Answer and explanation

They are in the same group and each has a single electron in its outer shell, which is easily lost. That shared electron arrangement is what makes them react in the same way, and the reactions become more vigorous down the group because the outer electron is further from the nucleus and more easily removed.

Response criteria

  • State a scientifically accurate conclusion.
  • Show the data, mechanism, or calculation that supports it.
  • Include units, conditions, or limits where relevant.

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