1.2Structure of Matter

The periodic table — EST 2 Chemistry Revision Notes & Topical Questions

5 min read 7 parts Lesson 2 of 5 1 quiz

📚 EST 2 Chemistry Hub / Topical Revision

0%read

Lesson summary

The periodic table EST Chemistry notes: Relate position to electron configuration.Fluorine is the most electronegative element.Cations are smaller than their atoms; anions are larger.A big jump in successive ionization energies reveals the number of valence electrons.Noble gases …

Isoelectronic ions
The periodic table EST Chemistry: what to do next
Atomic radius
Ionization energy
Electronegativity
Identify / Describe (FRQ)

Section 1 of 7The periodic table

s, p, d and f blocks match the sublevel being filled.

Transition metals form coloured ions.

Reactivity of alkali metals increases down the group.

Reactivity of halogens decreases down the group.

Isoelectronic ions

Isoelectronic ions more protons means smaller radius.

Section 2 of 7Process & sequence

Across a period, protons increase but shielding is nearly constant.

Nuclear pull on valence electrons increases.

Atoms shrink and hold electrons more tightly.

Down a group, new energy levels are added.

Atoms grow and lose electrons more easily.

Explaining a trendwrite these steps in this order; each step is a marking point.

Count protons

Consider shielding

Judge nuclear pull

Predict size

Predict ionization energy

Section 3 of 7Keep going

The periodic table EST Chemistry: what to do next

These The periodic table EST Chemistry notes covered the key ideas, worked examples and exam technique for this topic. Check your The periodic table EST Chemistry understanding with the practice questions below, then reread any The periodic table EST Chemistry point you were unsure about before moving on.

Practice: The periodic table EST Chemistry practice questions

Previous lesson: 1.1 Atomic structure

Next lesson: 1.3 Bonding

Course: EST 2 Chemistry — all units

Official syllabus: OpenStax free science textbooks

The periodic table EST Chemistry revision notes

Section 4 of 7Compare

Periodic trends
Property	Across a period (→)	Down a group (↓)
Atomic radius	Decreases	Increases
Ionization energy	Increases	Decreases
Electronegativity	Increases	Decreases
Metallic character	Decreases	Increases

Key groups
Group	Name	Valence ending	Typical ion
1	Alkali metals	ns¹	+1
2	Alkaline earth metals	ns²	+2
17	Halogens	ns²np⁵	−1
18	Noble gases	ns²np⁶	none

Section 5 of 7Key terms

Section 6 of 7Command terms

Command terms

Identify / Describe (FRQ)

A short, specific statement; describing requires relevant characteristics, not a single word.

Explain / Justify (FRQ)

Give the cause-and-effect reasoning or evidence; a restated fact does not score.

Calculate

Show setup, substitution and the answer with units.

Predict

State the expected outcome; add a reason only if asked to justify.

MCQ technique

Read every option; eliminate distractors that are true statements but do not answer the question; watch for NOT/EXCEPT.

Section 7 of 7Exam technique

Keywords the mark scheme looks for in this lesson

Period · Group · Atomic radius · Ionization energy · Electronegativity · Shielding · Metalloid

Learn each definition in the Key words tab exactly; a missing keyword in a definition usually loses the mark.

How to get full marks (examiner guidance)

Answer exactly what is asked; extra correct material does not earn credit, and contradictory statements can cancel credit (AP FRQ).

Use precise vocabulary (e.g. “active site”, “concentration gradient”, “allele”), never “it/stuff/things”.

Show units and working in calculations.

In MCQs, predict the answer before reading the options, then eliminate.

Last updated: 18 October 2026