Question

Define the term -'mass number ‘of an atom. If an atom ’B' has mass number 35 and atomic number 17, state the number of protons , electrons, and neutrons it contains

Answer 1

Understanding the concept: An atom is the smallest particle of matter which is made up of three subatomic particles electrons, protons, and neutrons.

Explanation:

Mass number(A): The total number of protons and neutrons present in a nucleus of an atom is called a mass number. It is denoted by ‘A’.

If an atom ‘B’ has an atomic number(Z) 17 and maas number (A) 35. Its mass number can be calculated by a formula;

• Mass number = Number of neutrons + number of protons( atomic number)
• 35 = number of neutrons + 17
• Number of neutrons =35-17
• Number of neutrons =18.
• A number of an electron in a neutral atom is always equal to the number of protons, thus a number of electrons are equal to a number of protons =17.