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Science · Chemistry

Periodic Table

Read trends in atomic radius, electronegativity, and reactivity directly off the table's rows and columns — the periodic table isn't just a reference chart, it's organized so that position predicts behavior. Every question comes with a written explanation of the trend involved.

Practise periodic table nowSee sample questions
3
Difficulty tiers
25s
Target pace
55%
Average first-attempt score

What's covered

  • Periods and groups — read a period as a horizontal row (increasing atomic number left to right) and a group as a vertical column (elements sharing similar chemical properties).
  • Atomic radius trend — recognize that atomic radius decreases across a period (left to right) and increases down a group.
  • Electronegativity trend — recognize that electronegativity increases across a period and decreases down a group — the opposite pattern from atomic radius.
  • Metals, nonmetals, and metalloids — locate metals on the left and center, nonmetals on the right, and metalloids along the zigzag staircase dividing the two.
  • Reactivity trends — connect reactivity to how easily an element gains or loses electrons — reactive metals sit on the far left, reactive nonmetals on the far right (excluding noble gases).

Where students lose marks

Applying atomic radius and electronegativity trends in the same direction

Atomic radius decreases across a period while electronegativity increases across it — the two trends run in opposite directions, and assuming they move together reverses one of them.

Confusing periods and groups

A period is a row, a group is a column — mixing up which one a trend is described across flips whether a rule applies moving across a row or down a column.

Assuming reactivity increases the same way for metals and nonmetals

Metal reactivity increases toward the left and bottom of the table (easier to lose electrons), while nonmetal reactivity increases toward the right and top (easier to gain electrons) — the two trends point in different directions because losing and gaining electrons are opposite processes.

Three sample questions

Straight from the bank — one per difficulty tier. Reveal the answer to see the explanation you'd get in a real session.

Sample 01Foundation

Which element has a larger atomic radius: sodium (Na) or chlorine (Cl)? Both are in the same period.

Sample 02Core

Which element is expected to have a higher electronegativity: fluorine (F) or iodine (I)? Both are in the same group (Group 17).

Sample 03Advanced

An element X is in Period 3 and has a smaller atomic radius but a higher electronegativity than an element Y in the same period. Based on periodic trends alone, what can be concluded about their relative positions?

How to practise this

Periodic table trend questions are fast once the two core directions — radius shrinking, electronegativity growing, both moving left to right — are automatic, since nearly every other trend follows from those two.

State the trend's direction before applying it to specific elements

For every trend question, say which direction — across a period, down a group — the property increases before naming the two elements. Untimed practice is where that direction-first habit sticks.

Then 25 seconds a question

Move to timed sessions once the core trends are instant recall. These should be some of the fastest Chemistry questions once the directions are locked in.

Fold into a mock

Pair the periodic table with chemical bonding in a mock — electronegativity trends are exactly what predicts bond type.

Stop guessing the direction.
Start naming the trend first.

  • A trend-by-trend walkthrough on every item
  • Timed or untimed sessions, any length you like
  • Tracked separately — see your periodic table accuracy and pace over time
Start practising free

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Related Science subtopics

Atomic StructureChemical BondingChemical ReactionsGas LawsAll of Science