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An atom has 17 protons, 18 neutrons, and 17 electrons. What is its mass number?
18
35
24
34
35
The mass number (also known as the atomic mass number) of an atom is defined as the sum of the number of protons and neutrons in its nucleus. Since the mass of electrons is negligible, the mass number is calculated by adding the protons and neutrons.
The mass number (also known as the atomic mass number) of an atom is defined as the sum of the number of protons and neutrons in its nucleus. Since the mass of electrons is negligible, the mass number is calculated by adding the protons and neutrons.
Think of the nucleus as a small bag containing marbles. Protons are red marbles and neutrons are blue marbles. The total count of marbles in the bag is the mass number, regardless of how many tiny, light 'dust particles' (electrons) are hovering outside the bag.
MAN: Mass = Atomic number + Neutrons (or Protons + Neutrons).
A=Z+N тАФ Mass number equals number of protons plus number of neutrons.
An atom's identity is determined by its atomic number (number of protons). The mass number (A) represents the total count of nucleons (A=Z+N), where Z is the atomic number (number of protons) and N is the number of neutrons. Electrons reside in outer orbitals and contribute insignificantly to the total mass of the atom.
Protons and neutrons are collectively known as nucleons.
Electrons have a mass of approximately 1/1836 of a proton and are excluded from the mass number calculation.
The given atom with 17 protons is Chlorine (Cl).
Identification of isotopes.
Calculation of atomic weight.
Nuclear physics and chemistry calculations.
Atomic number (Z) = 17.
Neutron count (N) = 18.
Calculation: 17+18=35.
Option A (18) is the neutron count. Option C (24) and Option D (34) are incorrect results.
B is correct тАФ The mass number is calculated by adding the 17 protons and 18 neutrons, resulting in a total of 35.
Always verify if the question asks for Atomic Number (Z) or Mass Number (A). Remember that mass number is the sum of protons and neutrons, while the electron count only determines the charge or state of the atom.
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