The Nuclear Model of AtomCopy
1. What is at the center of an atom?
A. Electrons
B. Protons and electrons
C. Positively charged nucleus
D. A neutral core
2. What particles orbit the nucleus of an atom?
A. Neutrons
B. Protons
C. Electrons
D. Ions
3. Which part of the atom contains almost all its mass?
A. Electrons
B. Orbitals
C. Nucleus
D. Energy levels
4. The nucleus of an atom is:
A. Very large and negatively charged
B. Small and positively charged
C. Small and neutral
D. Large and positively charged
5. What did the alpha-particle scattering experiment show about atoms?
A. Electrons are heavier than protons
B. Atoms are mostly empty space
C. Protons orbit the nucleus
D. Atoms have no internal structure
6. What evidence from the alpha-particle scattering experiment supports the idea that the nucleus is small?
A. Most alpha particles bounced back
B. All alpha particles stopped
C. Most alpha particles passed straight through
D. Alpha particles created light
7. Why were some alpha particles deflected at large angles in Rutherford’s experiment?
A. They collided with electrons
B. They hit the neutron cloud
C. They came close to a dense, positively charged nucleus
D. They passed through empty space
8. What conclusion was made about the charge of the nucleus based on alpha-particle deflection?
A. The nucleus is negative
B. The nucleus is neutral
C. The nucleus is positive
D. The nucleus has alternating charge
9. Which two particles make up the nucleus?
A. Protons and electrons
B. Neutrons and electrons
C. Protons and neutrons
D. Neutrons and ions
10. What is the charge of a neutron?
A. +1
B. -1
C. 0
D. +2
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11. What happens when an atom loses one or more electrons?
A. It becomes neutral
B. It becomes a positive ion
C. It becomes a negative ion
D. Its mass increases
12. What happens when an atom gains electrons?
A. It becomes a positive ion
B. It turns into a different element
C. It becomes a negative ion
D. It disintegrates
13. Which of the following is the definition of the proton number (Z)?
A. Total number of nucleons
B. Number of protons in the nucleus
C. Number of electrons in the outer shell
D. Number of neutrons in the nucleus
14. What does the nucleon number (A) represent?
A. Number of electrons
B. Number of protons
C. Number of protons + neutrons
D. Number of protons – electrons
15. How do you calculate the number of neutrons in an atom?
A. A – Z
B. Z – A
C. A + Z
D. A × Z
16. Which of the following is a correct nuclide notation?
A. Z⁄AX
B. AXZ
C. ZAX
D. ₆¹²C
17. In the notation ₆¹²C, what does the 6 represent?
A. Mass number
B. Neutron number
C. Proton number
D. Isotope number
18. In the nuclide notation ₉¹⁹F, how many neutrons are present?
A. 10
B. 9
C. 19
D. 28
19. What is an isotope?
A. An atom with more electrons than protons
B. Atoms with same number of neutrons
C. Atoms with the same proton number but different neutron numbers
D. Atoms of different elements with equal mass
20. Which of the following are isotopes of hydrogen?
A. H-1, He-4, H-2
B. H-1, H-2, H-3
C. H-2, He-2, H-4
D. H-1, H-2, He-3
Answer key and explanations
1. Correct Answer: C
Explanation: The nucleus is at the center of the atom and is positively charged.
2. Correct Answer: C
Explanation: Electrons are negatively charged and orbit around the nucleus.
3. Correct Answer: C
Explanation: The nucleus contains almost all of the atom’s mass because electrons have negligible mass.
4. Correct Answer: B
Explanation: The nucleus is tiny compared to the atom and carries a positive charge due to protons.
5. Correct Answer: B
Explanation: Rutherford’s alpha-particle scattering experiment showed that most alpha particles passed through → atoms are mostly empty space.
6. Correct Answer: C
Explanation: Most alpha particles went straight through the foil, showing the nucleus is very small.
7. Correct Answer: C
Explanation: Large-angle deflections occurred when alpha particles passed close to the dense, positively charged nucleus.
8. Correct Answer: C
Explanation: Since some positively charged alpha particles were repelled, the nucleus must also be positive.
9. Correct Answer: C
Explanation: The nucleus is made up of protons and neutrons only.
10. Correct Answer: C
Explanation: Neutrons are neutral — they carry no electric charge.
11. Correct Answer: B
Explanation: Losing electrons causes the atom to become positively charged → positive ion.
12. Correct Answer: C
Explanation: Gaining electrons adds negative charge → negative ion.
13. Correct Answer: B
Explanation: The proton number (Z) is the number of protons in the nucleus and defines the element.
14. Correct Answer: C
Explanation: Nucleon number = number of protons + number of neutrons.
15. Correct Answer: A
Explanation: Neutron number = nucleon number (A) – proton number (Z).
16. Correct Answer: D
Explanation: Nuclide notation shows the element with proton number as subscript and nucleon number as superscript, e.g. ₆¹²C.
17. Correct Answer: C
Explanation: The number 6 is the proton number (atomic number).
18. Correct Answer: A
Explanation: Neutrons = A – Z = 19 – 9 = 10.
19. Correct Answer: C
Explanation: Isotopes are atoms with the same number of protons but different numbers of neutrons.
20. Correct Answer: B
Explanation: H-1, H-2 (deuterium), and H-3 (tritium) are the three isotopes of hydrogen.