If A represents atomic mass and Z represents atomic number, which of the following describes an atom after a proton is emitted from its nucleus?
A.
A-1,Z+1
B.
A+1,Z-1
C.
A-1,Z-1
D.
A+1,Z+1
The correct answer and Explanation is :
The correct answer is C. A-1, Z-1.
Explanation:
When a proton is emitted from the nucleus of an atom, the process is known as proton emission. This is a type of radioactive decay where the atom’s nucleus releases a proton, which is a positively charged particle.
Let’s break down how this emission affects the atomic mass (A) and the atomic number (Z) of the atom:
- Atomic Number (Z): The atomic number represents the number of protons in the nucleus of an atom. When a proton is emitted, the number of protons in the nucleus decreases by one. Therefore, the new atomic number becomes ( Z-1 ).
- Atomic Mass (A): The atomic mass is the sum of protons and neutrons in the nucleus. When a proton is emitted, the number of nucleons (protons and neutrons) in the nucleus decreases by one. Thus, the atomic mass also decreases by one. Hence, the new atomic mass becomes ( A-1 ).
For example, if we start with an atom of element X with atomic number Z and atomic mass A, emitting a proton changes the atom into a new element with an atomic number of ( Z-1 ) and an atomic mass of ( A-1 ).
To summarize:
- Before emission: Atomic number = Z, Atomic mass = A
- After proton emission: Atomic number = ( Z-1 ), Atomic mass = ( A-1 )
Thus, the resulting atom will be represented as having ( A-1 ) as the new atomic mass and ( Z-1 ) as the new atomic number. This explains why option C (A-1, Z-1) correctly describes the atom after a proton is emitted.