Which of the following statements about the mass number of...

Which of the following statements about the mass number of an atom is incorrect? It has a unit defined as a dalton. b. $\quad$ On Earth, it equals the atomic weight. c. Unlike the atomic weight of an atom, it does not change when gravitational forces change. d. It equals the number of electrons in an atom. e. $\quad$ It is the sum of the protons and neutrons in the atomic nucleus.

Which of the following statements about the mass number of an atom is incorrect?
It has a unit defined as a dalton.
b. $\quad$ On Earth, it equals the atomic weight.
c. Unlike the atomic weight of an atom, it does not change when gravitational forces change.
d. It equals the number of electrons in an atom.
e. $\quad$ It is the sum of the protons and neutrons in the atomic nucleus.

Labs

Want to see this concept in action?

NEW

Explore this concept interactively to see how it behaves as you change inputs.

View Labs

Key Concepts

Unified Atomic Mass Unit (Dalton)

The unified atomic mass unit, commonly known as the dalton, is a standard unit of mass used to express atomic and molecular masses. It is defined as one twelfth of the mass of a carbon-12 atom. While atomic weight is measured in daltons, the mass number itself is a simple count without any associated measurement unit.

Atomic Structure and Electron Count

In the atomic structure, the nucleus contains protons and neutrons while electrons orbit around the nucleus. The mass number pertains only to the nucleons (protons and neutrons) and does not include electrons, meaning it does not represent the number of electrons in an atom.

Mass Number

Mass number is the total count of protons and neutrons present in an atomic nucleus. It is an integer value that characterizes each isotope of an element and does not depend on external factors such as gravitational forces.

Atomic Weight

Atomic weight (or atomic mass) represents the weighted average mass of the atoms of an element, taking into account the natural abundance of each isotope. Unlike the mass number, it is a calculated average and is typically measured in unified atomic mass units (daltons).

Transcript

Please give Ace some feedback