Medium Level Atomic Structure Questions

1. An atom has an atomic number of 15 and mass number 31. Calculate:

a) Number of protons

b) Number of neutrons

c) Number of electrons (if neutral)

a) 15, 16, 15
b) 31, 15, 31
c) 15, 31, 15
d) 16, 15, 16

2. When an electron absorbs electromagnetic radiation and moves to a higher energy level, what happens when it returns to its original level?

a) It absorbs more radiation
b) It emits radiation with lower energy
c) It emits radiation with equal energy to what was absorbed
d) No radiation is emitted

3. Why does lithium-7 have different properties from lithium-6, despite both being the same element?

a) Different number of electrons
b) Different number of protons
c) Different number of neutrons affecting mass but not chemical properties
d) Different energy levels

4. What happens to the atomic number and mass number when an atom loses two electrons?

a) Both decrease by 2
b) Atomic number decreases by 2, mass number stays same
c) Mass number decreases by 2, atomic number stays same
d) Both stay the same

5. Which conclusion about atomic structure came from the alpha particle scattering experiment?

a) Atoms contain electrons
b) Atoms contain specific energy levels
c) Most of an atom's mass is concentrated in a small, positive nucleus
d) Atoms contain neutrons

6. If chlorine has an atomic mass of 35.5, what does this suggest about naturally occurring chlorine?

a) All chlorine atoms have 35.5 protons
b) It's a mixture of isotopes, mainly chlorine-35 and chlorine-37
c) Chlorine atoms have a fractional number of neutrons
d) Some chlorine atoms have half electrons

7. A neutral atom has 18 electrons. An ion of the same element has 16 electrons. What is the charge on the ion?

a) -2
b) +2
c) -16
d) +16

8. How does the Bohr model improve upon Rutherford's nuclear model?

a) It shows electrons orbit in fixed energy levels
b) It shows the nucleus contains neutrons
c) It shows electrons have negative charge
d) It shows the nucleus is positive

9. What experimental evidence suggests that electron energy levels are quantized (fixed)?

a) Alpha particle scattering
b) Atoms emit only specific frequencies of light
c) Existence of isotopes
d) Formation of ions

10. Which statement correctly explains why atoms form positive ions?

a) They gain protons
b) They lose electrons, leaving more protons than electrons
c) They gain neutrons
d) They lose neutrons