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CAIE A-Level Chemistry 1.1 Particles and Atomic Radius

Practise describing atomic particles, calculating particle numbers and explaining radius trends from nuclear charge and shielding.

Syllabus
2028–2030
Course
Chemistry 9701
Level
AS

Exam points

  • use proton and nucleon numbers with ionic charge to determine protons, neutrons and electrons
  • compare particle mass and charge to predict deflection in an electric field at equal velocity
  • explain radius trends using shell number, shielding, nuclear charge and attraction to outer electrons

Covered syllabus points

1.1.1—Atomic structure and nucleus1.1.2—Protons, neutrons and electrons1.1.3—Terms: atomic and proton number, mass1.1.4—Distribution of mass and charge within an atom1.1.5—Behaviour of beams of protons, neutrons1.1.6—Determine the numbers of protons, neutrons1.1.7—Trends: the variations in atomic radius

1.1 Particles in the atom and atomic radius question 1

[Maximum number: 1]

Neutrons are passed through an electric field. The mass of one neutron relative to 112\frac{1}{12} the mass of a 12C{ }^{12} \mathrm{C} atom and any deflection in the electric field is recorded.

Which row is correct?

mass of

neutron

behaviour of beam of

neutrons in an electric field

0

deflected

1

deflected

0

not deflected

1

not deflected

1.1 Particles in the atom and atomic radius question 2

[Maximum number: 9]

Question (a)

(a)

The Group 2 elements form stable 2+ cations.

[ 2 ]

Question (i)

(i)

State and explain the variation in ionic radius of the Group 2 elements down the group.

[ 2 ]

Question (b)

(b)

All the Group 2 elements except beryllium have more than one stable isotope.

[ 7 ]

Question (i)

(i)

Beryllium exists as the single isotope 49Be{ }_{4}^{9} \mathrm{Be}.

Describe the distribution of mass within an atom of 49Be{ }_{4}^{9} \mathrm{Be}.

[ 2 ]

Question (ii)

(ii)

Complete Table 2.2 to show the numbers of protons and neutrons in the isotopes of magnesium.

Table 2.2

Table 2.2

[ 2 ]

Question (iii)

(iii)

Fig. 2.1 shows the behaviour of a beam of protons in an electric field.

Complete Fig. 2.1 to show the behaviour of separate beams of neutrons and electrons in the same electric field.

Label your diagram clearly. Assume that the beams of each particle are moving at the same velocity.

Fig. 2.1

Fig. 2.1

[ 3 ]
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