Junior Secondary · Science

Atoms and elements : Practice Questions

5 multiple-choice questions marked as you go, and 5 written questions with worked solutions. All on Atoms and elements .

10 questions27 marksFree, no account

Question 1

1 mark

Which of the following is the correct chemical symbol for the element Magnesium?

Question 2

1 mark

The identity of a chemical element is uniquely determined by the number of a specific subatomic particle. Which particle is this and where is it found within an atom?

Question 3

1 mark

A hypothetical ion $ X^{3+} $ is found to have a total of 25 subatomic particles located within its nucleus. If the ion currently possesses 10 electrons, how many neutrons does it have?

Question 4

1 mark

What is the electrical charge of a neutron?

Question 5

1 mark

A neutral atom of element X has a mass number of $$31$$ and contains $$16$$ neutrons. How many electrons does a neutral atom of element X possess?

Question 6

2 marks

What is the smallest basic unit of an element that still retains the chemical properties of that element?

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Question 7

3 marks

Describe the location and relative charge of protons, neutrons, and electrons within an atom.

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Question 8

6 marks

An unknown atom, denoted as $$X$$, has 17 protons and 18 neutrons. This atom can form an ion with a charge of $$-1$$.

a) Determine the mass number of atom $$X$$.

b) Calculate the total number of electrons in the ion formed from atom $$X$$.

c) Explain how an isotope of atom $$X$$ would differ in terms of its subatomic particles, and state one similarity it would share with atom $$X$$ itself.

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Question 9

5 marks

All matter is made up of tiny particles called atoms. Scientists classify these atoms into different elements, each with unique properties.

(a) Briefly explain what an element is in terms of its constituent atoms.

(b) A neutral atom of the element Magnesium (Mg) has an atomic number of 12.

(i) How many electrons are present in this neutral Magnesium atom? Explain your answer.

(ii) If the mass number of this specific Magnesium atom is 24, calculate the number of neutrons it contains. Show your working.

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Question 10

6 marks

An atom of an unknown element, denoted as X, has 11 protons, 12 neutrons, and 11 electrons.

a) What is the atomic number of element X? Explain how you determined this.
b) Calculate the mass number of element X. Show your working.
c) Based on its atomic number, would element X be classified as a metal or a non-metal? Justify your answer by referring to its likely position in the Periodic Table.

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