Question

An atom has mass number 23 and atomic number 11. How many protons, electrons and neutrons are present in the atom?
A.11,12,13
B.11,11,12
C.11,11,13
D.11,14,15

Answer 1

Hint: We have to know that the total number of the protons and neutrons present inside the nucleus is called the mass number. The number of protons present in the nucleus is the atomic number. We can calculate the number of neutrons by subtracting the mass number from the atomic number and the number of electrons and protons is given by the atomic number.

Complete answer:
Given data contains,
Mass number is 23.
Atomic number is 11.
For an element $\text{E}$, the top left number signifies the mass number and the bottom left number signifies the atomic number.

The letter A indicates mass number.
The letter Z indicates atomic number.
We must remember that the isotopes of elements contain the same number of protons but dissimilarity is seen in the different number of neutrons.
We can give the number of protons as,
The number of protons present in the nucleus is equal to the atomic number of an atom.
The atomic number of atoms is 11.
The number of protons in an atom is 11.
We know that the number of protons present in the nucleus is equal to the number of electrons orbiting around the nucleus.
The number of protons of an atom is 11, so the number of electrons in an atom is also 11.
We can calculate the number of neutrons present in the atom by subtracting the mass number from the number of protons.
We can write the formula to obtain the number of neutrons as,
Number of neutrons$=\text{Mass number}-\text{Number of protons}$
We know that the mass number is 12 and the number of protons is 11. Substituting the values, we get the number of protons.
Number of neutrons$=\text{Mass number}-\text{Number of protons}$
Number of neutrons=$\text{23 - 11}$
Number of neutrons=$12$
The number of neutrons present in the atom is 12.
The number of protons present in an atom is 11.
The number of electrons present in an atom is 11.
The number of neutrons present in the atom is 12.
Therefore, the option (B) is correct.

Note: Let us consider an example of an element that contains atomic number 12, the number of protons and electrons present in the element will also be 12. Every element in the periodic table will contain various numbers of protons. Since an atom has an equal number of protons and electrons, we can say an atom is neutral in terms of electrical charge. The atomic number of the element is written front and slightly below the symbol of the element.
Example: For the given element ${}_2^{4}He$, the atomic number of the element two and the number of protons and electrons present in the element is also two.