Which of the following is the atomic number of an atom that has 12 protons and 12 neutrons?
A.
24
B.
12
C.
1
D.
144
The correct answer and Explanation is :
The atomic number of an atom is defined as the number of protons in its nucleus. Given that the atom in question has 12 protons, its atomic number is 12. Therefore, the correct answer is:
B. 12
Here’s a brief explanation:
The atomic number (Z) of an element is a fundamental property that defines the identity of the element. It represents the number of protons in the nucleus of an atom. In this case, the atom has 12 protons, which means its atomic number is 12.
The number of neutrons in an atom does not affect the atomic number. Instead, it contributes to the atom’s mass number. The mass number (A) is the sum of protons and neutrons in the nucleus. For the atom described, with 12 protons and 12 neutrons, the mass number is calculated as:
[ \text{Mass Number} (A) = \text{Number of Protons} + \text{Number of Neutrons} ]
[ A = 12 + 12 = 24 ]
Thus, the mass number of this atom is 24, but this is different from the atomic number. The atomic number remains defined solely by the number of protons, which in this case is 12.
So, while the mass number of this atom is 24, indicating that it is an isotope of an element with an atomic number of 12, the atomic number itself is simply 12.