How do I read a period and a group?

Periods are rows, set by the number of shells; groups are columns, set by outer-shell electrons.

What separates atomic number from mass number?

Atomic number is the proton count; mass number is protons plus neutrons.

S4 Chemistry: The Periodic Table — Practice Paper 1 (10 Questions)

2026-11-03

Paper 1 fixes the language of position: atomic number, electron arrangement, and how to read periods and groups, then adds mass number arithmetic.

Quick answer　Ten questions, about 20 minutes. Items 01 to 04 cover atomic number and arrangement; 05 to 07 cover group patterns, the metal divide and symbols; 08 to 09 cover mass number and neutrons; item 10 redoes reading a period as a group.

01　Paper details (check answers afterwards)

Item	Detail
Questions	10 questions
Suggested time	20 minutes
Difficulty mix	Foundation 4 · Intermediate 3 · Challenge 2 · Error redo 1
Chapter	Chapter: Secondary 4 Maths: Equivalent Fractions and Decimals — Tutor Lesson Plan
Level	Secondary 4

02　Questions (10 items)

FoundationHydrogen has atomic number 1. How many protons and electrons does one hydrogen atom contain?
FoundationOxygen has atomic number 8. Give its electron arrangement and outer-shell count.
FoundationSodium is 2, 8, 1. Which period and which group is it in?
FoundationChlorine has atomic number 17. Give its arrangement and group.
IntermediateWhat do elements in the same group share?
IntermediateHow are metals and non-metals arranged in the table? Give one example each.
IntermediateWhat is the difference between Co and CO?
ChallengeA sodium atom has mass number 23. How many neutrons does it hold?
ChallengeCarbon-12 has 6 protons and 6 neutrons. What is its mass number?
Error redoError drill: why is calling sodium a Group 3 element wrong?

03　Answers and one-line notes

#	Answer	One-line note
1	One proton and one electron.	In a neutral atom the electron count equals the proton count.
2	2, 6; six electrons in the outer shell.	Electrons fill shells of 2, then 8, from the inside out.
3	Period 3, Group I.	Three shells means Period 3; one outer electron means Group I.
4	2, 8, 7; Group VII.	Seven outer electrons, one short of a full shell.
5	The same number of outer-shell electrons.	Every Group I element has a single outer electron.
6	Metals on the left (sodium), non-metals on the right (sulfur).	Elements near the dividing line show properties of both.
7	Co is cobalt; CO is carbon monoxide.	A capital second letter signals another element; a lower-case one keeps the same element.
8	23 minus 11 gives 12 neutrons.	Neutrons equal mass number minus atomic number.
9	12.	Mass number is protons plus neutrons.
10	Sodium is Period 3, Group I.	A period is a row (shell count); a group is a column (outer electrons).

04　What to do after marking

After marking, redo only the wrong items and write down which step went wrong (formula, unit, or misread number).
Repeat the same item two days later; move to the next paper only when both attempts are correct.
Parents only need the answer and note columns; there is no need to explain every item.

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