Chemistry · Unit 2

The Periodic Table

Groups, periods and trends

The periodic table is not a filing cabinet. It is arranged so that position predicts behaviour, and that predictive power is why it was accepted before anyone knew about electrons.

The unit covers groups and periods, element symbols, metals and non-metals, and the noble gases - the group whose near-total unreactivity explains, by contrast, why everything else reacts.

This unit breaks down into 16 short steps and 95 questions, starting at difficulty 1 and building to 3. Below you can see exactly what it covers, how the path is structured, and worked examples with explanations.

Steps: 16
Questions: 95
Difficulty: 1-3

What this unit covers

Metal
Noble Gas
Period
Element Symbol
Group

Where this fits

Follows Atoms. Chemical Bonding depends on being able to read a group number.

Where people slip

Group number tells you outer electrons, and that is the point of it. Elements in a group behave alike because they have the same outer arrangement, not because they sit near each other on a chart.

How the unit is structured

The Periodic Table runs as 16 short steps that unlock in order. 12 are practice rounds and 4 are challenge rounds that pull together everything before them. Questions start at difficulty 1 and climb to 3 as you progress.

Step 1 · easierStep 16 · harder

Challenge rounds

Example questions

30 real questions from this unit, with the answer and the reason behind it, grouped by what they practise. There are 95 in the unit altogether.

Element Symbol

Multiple choiceLevel 1
1. Which element does the chemical symbol 'O' represent?
- Oxygencorrect
- Osmium
- Gold
- Oxide
The symbol O stands for oxygen.
Type the answerLevel 1
2. Type the chemical symbol for the metal calcium.
Answer: Ca
Calcium has the chemical symbol Ca.
Fill the blankLevel 2
3. Mendeleev first arranged the known elements in order of increasing atomic ____.
- masscorrect
- number
- radius
- colour
Mendeleev ordered elements by atomic mass, whereas the modern table uses atomic number.
Match the pairsLevel 2
4. Match each element to its chemical symbol.
Answer: Hydrogen = H; Carbon = C; Iron = Fe; Gold = Au
Hydrogen is H, carbon is C, iron is Fe, and gold is Au.
Spell itLevel 2
5. Spell the chemical symbol for sodium.
Answer: Na
Sodium's symbol is Na, from its Latin name natrium.
True or falseLevel 2
6. Mendeleev left gaps in his periodic table so that elements not yet discovered could be added later.
Answer: True
Mendeleev left gaps and even predicted the properties of elements that were discovered afterwards.

Group

Multiple choiceLevel 1
7. What is a vertical column of elements in the periodic table called?
- A groupcorrect
- A period
- A shell
- A block row
Elements stacked in a vertical column form a group.
Build the sentenceLevel 2
8. Build the sentence that explains what elements in the same group share.
Answer: Atoms in the same group have equal numbers of outer electrons
Elements in the same group have the same number of electrons in their outer shell.
Fact or fibLevel 2
9. The reactivity of the Group 1 alkali metals increases as you go down the group.
Answer: True
Reactivity increases down Group 1 because the outer electron is lost more easily from larger atoms.
Fill the blankLevel 2
10. When sodium reacts with water it makes a solution that turns universal indicator blue because the solution is ____.
- alkalinecorrect
- acidic
- neutral
- sugary
The reaction produces sodium hydroxide, which makes the water alkaline.
Guess the numberLevel 2
11. How many electrons are in the outer shell of an element in Group 2?
Answer: 2 electrons
For the main groups, the group number gives the number of outer-shell electrons, so Group 2 has 2.
Match the pairsLevel 2
12. Match each halogen to its appearance at room temperature.
Answer: Fluorine = Pale yellow gas; Chlorine = Green gas; Bromine = Red-brown liquid; Iodine = Grey-black solid
Halogens are coloured: fluorine a pale yellow gas, chlorine a green gas, bromine a red-brown liquid and iodine a grey-black solid.

Metal

Fact or fibLevel 1
13. Silicon, a metalloid, is widely used to make the microchips inside computers.
Answer: True
Silicon's semiconductor behaviour makes it ideal for computer chips.
Multiple choiceLevel 1
14. Which of these is a typical property of non-metals?
- They are brittle when solidcorrect
- They are always shiny
- They conduct electricity very well
- They can be hammered into thin sheets
Non-metals are usually brittle when solid and are poor conductors, unlike shiny, bendable metals.
Odd one outLevel 1
15. Which of these is NOT a typical property of metals?
- Brittle and shatters easilycorrect
- Good conductor of electricity
- Shiny when polished
- Can be bent into shape
Metals are usually shiny, bendable and good conductors; being brittle and shattering is a non-metal property.
Picture questionLevel 1
16. 🥇 Gold, like the medal shown, is an example of which type of element?
- A metalcorrect
- A noble gas
- A nonmetal
- A liquid
Gold is a metal - shiny, solid at room temperature, and a good conductor.
Fill the blankLevel 2
17. Elements such as silicon that have some properties of metals and some of non-metals are called ____.
- metalloidscorrect
- halogens
- noble gases
- alkali metals
Metalloids, or semi-metals, sit along the staircase line and behave partly like metals and partly like non-metals.
Sort into groupsLevel 3
18. Sort each element as a metal or a nonmetal.
Answer: Iron = Metal; Copper = Metal; Oxygen = Nonmetal; Sulfur = Nonmetal
Iron and copper are metals; oxygen and sulfur are nonmetals.

Noble Gas

Fact or fibLevel 1
19. Noble gases are very unreactive elements.
Answer: True
Noble gases have full outer electron shells, which makes them very stable and unreactive.
Multiple choiceLevel 1
20. The elements in Group 18 of the periodic table are known as what?
- Noble gasescorrect
- Alkali metals
- Halogens
- Metalloids
Group 18 contains the noble gases, such as helium and neon.
Picture questionLevel 1
21. 💡 The bright orange-red glow of many advertising signs comes from a Group 0 gas. Which noble gas is it?
- Neoncorrect
- Helium
- Argon
- Krypton
Neon is used in glowing signs because it emits a bright orange-red light when electricity passes through it.
Choose all that applyLevel 2
22. Which of these elements are noble gases? Select all that apply.
- Heliumcorrect
- Argoncorrect
- Nitrogen
- Chlorine
Helium and argon are noble gases in Group 0; nitrogen and chlorine are not.
Odd one outLevel 2
23. Which of these elements is NOT a noble gas?
- Oxygencorrect
- Helium
- Neon
- Argon
Helium, neon, and argon are noble gases; oxygen is not.
Sequence recallLevel 2
24. Memorise the first three noble gases in order of increasing atomic size, then repeat the sequence.
Answer: Helium -> Neon -> Argon
Going down Group 0 the atoms get bigger, so the order is helium, then neon, then argon.

Period

Fill the blankLevel 1
25. A horizontal row of elements in the periodic table is called a ____.
- Periodcorrect
- Group
- Family
- Column
Each horizontal row across the table is called a period.
Choose all that applyLevel 2
26. Select the properties that generally INCREASE across period 3 from sodium to chlorine.
- First ionisation energycorrect
- Electronegativitycorrect
- Effective nuclear charge felt by the outer electronscorrect
- Atomic radius
Across period 3 the effective nuclear charge, electronegativity and first ionisation energy all rise, while the atomic radius decreases.
Guess the numberLevel 2
27. How many periods (horizontal rows) are there in the standard periodic table?
Answer: 7 periods
The standard periodic table has 7 periods.
Multiple choiceLevel 2
28. Atomic radius decreases across period 3 from sodium to chlorine. What is the main reason for this trend?
- The nuclear charge increases while electrons are added to the same shell, pulling them in more strongly
- Extra electron shells are added, which increases shielding
- The number of neutrons decreases across the period
- The atoms gain electrons and become negative ions
Across period 3 the number of protons rises but electrons enter the same third shell, so the increasing nuclear charge pulls the outer electrons closer and the atomic radius decreases.
Build the sentenceLevel 3
29. Build the main reason first ionisation energy generally rises across a period.
Answer: nuclear charge increases and atomic radius decreases
Across a period the nuclear charge increases and the atomic radius decreases, so outer electrons are held more tightly and more energy is needed to remove one.
Fact or fibLevel 3
30. Silicon has the highest melting point in period 3 because it forms a giant covalent (macromolecular) structure.
Answer: True
Silicon's atoms are held in a giant covalent lattice, so a huge number of strong covalent bonds must be broken to melt it, giving period 3's highest melting point.

Where these questions come from. Each unit starts as a plan of the concepts it should cover and the difficulty it should span. Questions are written against that plan with AI assistance, then checked by a validator that rejects anything without a single defensible answer, an explanation, or plausible wrong options. How we write questions sets out the whole process, and corrections are fixed in the bank and reach the site and the app the same day.

How you practise

This unit mixes 17 different question formats, so you are recalling and applying rather than recognising the same layout every time.

Build the sentence
Choose all that apply
Fact or fib
Fill the blank
Guess the number
Listen and choose
Match the pairs
Multiple choice
Odd one out
Picture question
Put in order
Sequence recall
Sort into groups
Spell it
Tap the pairs
True or false
Type the answer

Practise The Periodic Table

95 questions across 16 steps. Start with step one and crawl at your own pace.

Play this unit

Read about The Periodic Table

Explainers from our blog on what this unit covers. Each one ends with real questions from the bank.

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