Learners' AlleyDesigned by Khow Willard

Atomic Structure

Set AFoundations

Name

Time 50 minutes

Total 28 marks

Use a copy of the Periodic Table where you need one.

From the lesson

9 marks

Which statement about atoms of chlorine-35 and chlorine-37 is correct?

AThey have the same number of neutrons.

BThey have the same nucleon number.

CThey have the same number of electrons.

DThey have the same mass.

Answer [1]

Source: Learners' Alley, Atomic Structure slides

Calcium has proton number 20. What is its electronic configuration?

A2.4.6.8

B2.6.8.4

C2.8, 10

D2.8.8.2

Answer [1]

Source: Learners' Alley, Atomic Structure slides

Complete the table. The first row is done for you.

particle	protons	neutrons	electrons
¹⁸⁴₇₄W	74	110	74
an atom of uranium-235 (proton number 92)
a sodium ion with a charge of +1 (a sodium atom has 11 protons and 12 neutrons)
³²₁₆S²⁻

[3]

Source: Learners' Alley, Atomic Structure slides

Boron-11 is the most common isotope of boron. Boron has proton number 5.

(a)

How many protons, neutrons and electrons does an atom of boron-11 have?

[1]

(b)

What is its electronic configuration?

[1]

Source: Learners' Alley, Atomic Structure slides

ChallengeArsenic is a toxic element with proton number 33. Arsenic and its compounds react in the same way as phosphorus and its compounds. Phosphorus has proton number 15. Arsenic has 5 valence electrons.

Suggest why arsenic and its compounds react in the same way as phosphorus and its compounds.

[2]

Source: Learners' Alley, Atomic Structure slides

Practice

19 marks

Which option correctly describes the locations of the sub-atomic particles in an atom?

	proton	neutron	electron
A	in the nucleus	in the nucleus	orbiting the nucleus
B	in the nucleus	in the nucleus	in the nucleus
C	orbiting the nucleus	in the nucleus	orbiting the nucleus
D	orbiting the nucleus	orbiting the nucleus	in the nucleus

Answer [1]

Source: 2023 GESS Sec 3 End-of-Year P1 Q8

Which statement about an atom is true?

AThe proton number can be more than the nucleon number.

BThe proton number of all atoms of an element is the same.

CThe nucleon number cannot be equal to the proton number.

DThe nucleon number cannot be equal to the number of electrons.

Answer [1]

Source: 2023 HYSS Sec 3 End-of-Year P1 Q6

In which of the following sets do all the particles have the same number of electrons?

AF⁻, Cl⁻, Br⁻

BH⁺, He, N³⁻

CK⁺, Ca²⁺, P³⁻

DNa⁺, Mg²⁺, S²⁻

Answer [1]

Source: 2023 GESS Sec 3 End-of-Year P1 Q11

Chlorine-37 is an isotope of chlorine.

(a)

Explain what is meant by the term isotope.

[2]

(b)

An ion of chlorine-37 contains the particles in Table 9.1. Identify particles X, Y and Z.

particle	number	name of particle
X	20
Y	18
Z	17

[2]

(c)

Chlorine-35 is another isotope of chlorine. Complete Table 9.2 to show the number of each type of particle in an atom of chlorine-35.

particle	number
X
Y
Z

[2]

Source: BLSS 2024 Sec 4 Prelim P2 Q3, adapted

(a)

Table 10.1 describes the properties of some sub-atomic particles. Complete Table 10.1.

	relative mass	relative charge
proton
neutron
electron

[2]

The symbol of an atom of aluminium is ²⁷₁₃Al.

(b)

Answer the following about this atom of aluminium.

(i)

State the number of neutrons it has.

[1]

(ii)

Write the electronic configuration of this atom of aluminium.

[1]

(iii)

The symbol for another atom of aluminium is ²⁶₁₃Al. State and explain the relationship between these two atoms of aluminium.

[1]

Source: 2023 GESS Sec 3 End-of-Year P2 Q5

Flerovium, Fl, has proton number 114. It was first made in research laboratories in 1998. Two isotopes of flerovium are ²⁸⁶Fl and ²⁸⁹Fl.

(a)

Define the term isotope.

[1]

(b)

Complete Table 11.1 to show the number of protons, neutrons and electrons in the isotopes shown.

isotope	protons	neutrons	electrons
²⁸⁶Fl
²⁸⁹Fl

[2]

Source: CHS Sec 3 End-of-Year Section B Q5(b)

Table 12.1 shows information about two atoms. Complete Table 12.1.

atom	protons	neutrons	electrons
³⁹₁₉K
		28	24

[2]

Source: 2025 TKGS Sec 4 Prelim P2 Q2(a)