BMST - Basic Math and Science Atomic Structure and Bonding Questions and Answers 4 — Questions and Answers
Question 1: Carbon-12 and Carbon-14 are isotopes. How do they differ?
- Number of protons
- Number of electrons
- Number of neutrons (Correct answer)
- Atomic number
Correct answer: Number of neutrons
Carbon-12 has 6 neutrons while Carbon-14 has 8 neutrons; both have 6 protons.
Question 2: Which property of an atom is represented by its mass number?
- Number of protons only
- Number of electrons only
- Total number of protons and neutrons (Correct answer)
- Total number of protons and electrons
Correct answer: Total number of protons and neutrons
The mass number equals the sum of protons and neutrons in the nucleus.
Question 3: A polar covalent bond forms when two atoms share electrons:
- Equally, because both atoms have identical electronegativity
- Unequally, because one atom pulls electrons more strongly (Correct answer)
- By full transfer of one electron to the other atom
- Through electrostatic attraction between oppositely charged ions
Correct answer: Unequally, because one atom pulls electrons more strongly
In polar covalent bonds, the more electronegative atom attracts the shared electrons more strongly.
Question 4: Which of the following best describes a cation?
- An atom that has gained one or more electrons
- An atom that has lost one or more electrons (Correct answer)
- An atom with more neutrons than protons
- A neutral atom with paired electrons
Correct answer: An atom that has lost one or more electrons
A cation is a positively charged ion formed when an atom loses electrons.
Question 5: In the Bohr model of the atom, electrons emit energy when they:
- Move from a lower to a higher energy level
- Move from a higher to a lower energy level (Correct answer)
- Remain in the same energy level
- Are removed from the atom entirely
Correct answer: Move from a higher to a lower energy level
Electrons release a photon of energy when they fall from a higher to a lower energy level.
Question 6: Which statement about noble gases is correct regarding chemical bonding?
- They readily form ionic bonds with metals
- They easily share electrons with nonmetals
- They are largely unreactive due to a full valence shell (Correct answer)
- They always bond with oxygen to form oxides
Correct answer: They are largely unreactive due to a full valence shell
Noble gases have 8 valence electrons (or 2 for helium), giving them a stable configuration that makes them nearly inert.
Question 7: What determines the number of valence electrons in a main-group element?
- The period number
- The atomic mass
- The group number (Correct answer)
- The number of neutrons
Correct answer: The group number
For main-group elements, the group number (1–18 system: groups 1, 2, and 13–18) directly indicates the number of valence electrons.
BMST - Basic Math and Science Atomic Structure and Bonding Questions and Answers 4
Carbon-12 and Carbon-14 are isotopes.
How do they differ?