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Atomic Structure Practice Questions

Question 1

3 marks

In 1803 John Dalton described atoms as tiny solid spheres that could not be split into anything smaller. Later experiments led scientists to change this model.

(a)

Which statement describes an atom in Dalton's model?

Put a cross ( ☒ ) in the box next to your answer.

☐ A a sphere that cannot be divided into smaller particles

☐ B a nucleus that contains protons and neutrons

☐ C a nucleus surrounded by electrons in shells

☐ D a sphere with a very small nucleus at its centre

(b)

Describe two ways in which the model of the atom used today is different from Dalton's model.

Question 2

3 marks

An atom of magnesium is represented as 1225Mg^{25}_{12}\mathrm{Mg}

(a)

State the meaning of the term mass number of an atom.

(b)

Give the number of protons, neutrons and electrons in this magnesium atom.

Question 3

2 marks
(a)

Which row shows the relative mass and the relative charge of a neutron?

relative mass relative charge
A 1 +1+1
B 1 00
C very small −1-1
D very small 00

Put a cross ( ☒ ) in the box next to your answer.

(b)

Explain why almost all of the mass of an atom is found in its nucleus.