Free CART Atomic Structure Questions and Answers — Questions and Answers
Question 1: What is the atomic number of an element?
- The number of protons in an atom's nucleus (Correct answer)
- The number of neutrons in an atom's nucleus
- The number of electrons in an atom's nucleus
- The total number of protons and neutrons in an atom's nucleus
Correct answer: The number of protons in an atom's nucleus
The atomic number (Z) is fundamentally defined by the number of protons found in an atom's nucleus. This unique count of protons determines the identity of an element and its position on the periodic table, distinguishing it from all other elements.
Question 2: Which subatomic particles are located in the nucleus of an atom?
- Protons and electrons
- Neutrons and electrons
- Protons and neutrons (Correct answer)
- Electrons only
Correct answer: Protons and neutrons
The nucleus of an atom is the dense, central core where the majority of an atom's mass is concentrated. It is composed of positively charged protons and neutral neutrons, while electrons orbit the nucleus in electron shells.
Question 3: What is the charge of an electron?
- Positive
- Negative (Correct answer)
- Neutral
- Variable
Correct answer: Negative
Electrons are fundamental subatomic particles that carry a single negative elementary charge. This negative charge is crucial for their role in forming chemical bonds and interacting with other atoms.
Question 4: Isotopes of an element differ in the number of which subatomic particle?
- Neutrons (Correct answer)
- Protons
- Electrons
- Positrons
Correct answer: Neutrons
Isotopes are atoms of the same element, meaning they share the same number of protons and thus the same atomic number. They differ in their mass number because they have varying numbers of neutrons in their nucleus, leading to different atomic masses.
Question 5: Which of the following best describes the mass number of an atom?
- The total number of electrons in an atom
- The sum of the protons and neutrons in the nucleus (Correct answer)
- The number of protons in the nucleus
- The average mass of all isotopes of an element
Correct answer: The sum of the protons and neutrons in the nucleus
The mass number (A) of an atom represents the total count of protons and neutrons residing in its nucleus. It provides an approximate measure of the atom's mass in atomic mass units, as electrons contribute negligibly to the overall mass.
Free CART Atomic Structure Questions and Answers
What is the atomic number of an element?