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
My answer is B.
To determine the correct answer, let's first understand the concept of atomic mass (A) and atomic number (Z).
- Atomic mass (A) represents the total number of protons and neutrons in an atom's nucleus.
- Atomic number (Z) represents the number of protons in an atom's nucleus.
Now, let's analyze the given question. The question states that a proton is emitted from the atom's nucleus.
When a proton is emitted, it means that one proton is lost from the nucleus. Since protons are positively charged, losing a proton would result in a decrease in the overall positive charge of the nucleus.
Based on this information, let's evaluate the options:
A. A+ 1, Z + 1 - This option suggests an increase in both atomic mass (A) and atomic number (Z), which is incorrect because a proton is lost, not gained. Therefore, this option is incorrect.
B. A-1, Z-1 - This option suggests a decrease in both atomic mass (A) and atomic number (Z), which is correct. When a proton is emitted, both the atomic mass and atomic number decrease by one.
C. A+ 1, Z-1 - This option suggests an increase in atomic mass (A) and decrease in atomic number (Z), which is incorrect based on the concept discussed above. Therefore, this option is incorrect.
D. A-1, Z + 1 - This option suggests a decrease in atomic mass (A) and an increase in atomic number (Z), which is incorrect. Losing a proton would decrease the atomic mass, but it would not increase the atomic number. Therefore, this option is incorrect.
Therefore, the correct answer is B. A-1, Z-1, as it accurately describes an atom after a proton is emitted from its nucleus.