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How many protons, neutrons and electrons are in calcium?

Answer
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Hint: The atomic number of Ca is 20.
The mass number or atomic mass of Ca is 40.

Complete answer:
So in the question it is asked to write the number of protons, electrons and number of neutrons present in the Ca atom. In the lower classes we have studied about the three main subatomic species i.e. protons, electrons and neutrons. Let’s brush up our memory about these subatomic particles and trace the relation between the atomic number and atomic mass with the number of protons, neutrons and electrons.
From the time we study about an atom, we always have heard of protons, electrons and neutrons, that an atom consists of these three subatomic particles and it contributes to the atomic mass of an element and its stability. Now let’s grab some basic idea of these three.
Protons: these are the positively charged subatomic species which is present in the atomic nucleus and they are represented as ${{p}^{+}}$.The protons possess a charge of $+1.602\times {{10}^{-19}}C$ and a mass of$1.67\times {{10}^{-27}}Kg$.
Electrons: these are the negatively charged species present in the atom in contrast to the protons and these are the species which revolve around the nucleus and possess much smaller size than the atomic nucleus. The electron is represented as ${{e}^{-}}$ and they possess a charge of $-1.602\times {{10}^{-19}}C$ and has a mass of about$9.11\times {{10}^{-31}}kg$.
Neutrons: these are the neutral species present in the nucleus of the atom and they do not have charge. Neutron is represented as ${{n}^{0}}$ and has a mass of$1.67\times {{10}^{-27}}Kg$.
Atomic number is the unique number or can be said as the identity of an element. Each element possesses a unique atomic number. Atomic number is the number of electrons or the number of protons present in an atom.
Atomic number is the sum of the number of protons and neutrons present in the atomic nucleus.
Now let’jkss move on to the solution:
Since we know that the atomic number of Ca is 20, it gives the number of protons and electrons present in the atom.
$Number\,of\,protons\,=20$
$Number\,of\,electrons\,=20$
Now we have to find the number of neutrons.
The atomic number of Ca is 40.
$\text{Atomic}\,\text{mass=no}\text{.}\,\text{of}\,{{\text{p}}^{\text{+}}}\text{+no}\text{.}\,\text{of}\,{{\text{n}}^{\text{0}}}$
$\text{no}\text{.}\,\text{of}\,{{\text{n}}^{\text{0}}}\text{=Atomic}\,\text{mass-no}\text{.}\,\text{of}\,{{\text{p}}^{\text{+}}}$
$\text{no}\text{.}\,\text{of}\,{{\text{n}}^{\text{0}}}\text{=40-20=20}$
There number of neutrons is 20.
Hence the number of protons, neutrons and electrons in a Ca atom is 20.
$Number\,of\,protons\,=20$
$Number\,of\,electrons\,=20$
$Number\,of\,neutrons=20$

Note:
There is always a chance of getting confused with the calculation of the atomic mass and the atomic number, many add up the number of protons and electrons for atomic mass. The atomic nucleus accounts for the mass of the element.
$\text{Atomic}\,\text{number=No}\text{.}\,\text{of}\,\text{protons=No}\text{.}\,\text{of}\,\text{electrons}$
The number of protons and electrons will be the same in an atom.