3.1 Physical Chemistry

In the early twentieth century the apparatus shown in the diagram was used to investigate atomic structure. When He²⁺ particles were fired at a thin sheet of gold, most of the particles were detected at point P. What conclusion can be drawn from the detection of He²⁺ particles at point P?

• Gold atoms contain electrons.

• Gold atoms contain protons.

• Gold atoms contain neutrons.

• Gold atoms are mainly empty space.

When He²⁺ particles were fired at a thin sheet of gold, about 1 in 8000 of the particles were detected at point Q. What conclusion can be drawn from the detection of He²⁺ particles at point Q?

• Gold atoms have a small, positive nucleus.

• Gold atoms have electrons in orbitals.

• Gold consists of ions in a sea of delocalised electrons.

• Gold atoms have more protons than He2+ particles.

Which of these correctly shows the numbers of sub-atomic particles in a ⁴¹K⁺ ion?

• Number of electrons: 19, Number of protons: 19, Number of neutrons: 20

• Number of electrons: 18, Number of protons: 20, Number of neutrons: 21

• Number of electrons: 18, Number of protons: 19, Number of neutrons: 22

• Number of electrons: 19, Number of protons: 18, Number of neutrons: 23

Which of these correctly shows the numbers of sub-atomic particles in a ²¹Na⁺ ion?

• Number of electrons: 11, Number of protons: 11, Number of neutrons: 10

• Number of electrons: 10, Number of protons: 12, Number of neutrons: 9

• Number of electrons: 10, Number of protons: 11, Number of neutrons: 10

• Number of electrons: 11, Number of protons: 10, Number of neutrons: 11

Which of these correctly shows the numbers of sub-atomic particles in a ⁴²Ca²⁺ ion?

• Number of electrons: 20, Number of protons: 20, Number of neutrons: 22

• Number of electrons: 18, Number of protons: 21, Number of neutrons: 21

• Number of electrons: 18, Number of protons: 20, Number of neutrons: 22

• Number of electrons: 20, Number of protons: 19, Number of neutrons: 23

Which species has the same number of electrons as the radical •CH₃?

• CH₂

• CH₃⁺

• CH₃⁻

• CH₄⁺

What are the numbers of neutrons and electrons in the ⁵⁷Fe²⁺ ion?

• Neutrons: 31, Electrons: 24

• Neutrons: 57, Electrons: 24

• Neutrons: 31, Electrons: 26

• Neutrons: 57, Electrons: 28

Which of these atoms has the largest atomic radius?

• Ar

• Cl

• Mg

• Na

Which of these atoms has the smallest atomic radius?

• Ar

• Cl

• Mg

• Na

Which of these atoms has the smallest atomic radius?

• F

• O

• B

• Be