Bromine (Br) is atomic number 35. How many protons, neutrons, and electrons in a negative ion of Bromine-79 (Br” -79)?
A.
B. 35p, 44n, 36e
C. 35p, 79, 36e
D.
E 79p, 35, 36e
The correct answer and explanation is :
The correct answer is:
B. 35 protons, 44 neutrons, 36 electrons
Explanation:
Understanding Bromine-79
- Atomic number of Bromine (Br) = 35, meaning it has 35 protons in its nucleus.
- Mass number of Bromine-79 = 79. The mass number is the sum of protons and neutrons.
Finding the Number of Neutrons:
[
\text{Number of neutrons} = \text{Mass number} – \text{Atomic number}
]
[
79 – 35 = 44
]
So, Bromine-79 has 44 neutrons.
Finding the Number of Electrons:
- In a neutral atom, the number of electrons equals the number of protons.
- Bromine normally has 35 electrons in its neutral state.
- However, the problem states that it is a negative ion (Br⁻). A negative ion means it has gained an extra electron.
- Since Bromine is Br⁻ (with a charge of -1), it has gained one additional electron.
Thus, the total number of electrons in Br⁻-79 is:
[
35 + 1 = 36
]
Final Answer:
- Protons = 35
- Neutrons = 44
- Electrons = 36
- Correct option: B. 35p, 44n, 36e
Here is an image illustrating the structure of a Bromine-79 negative ion (Br⁻), showing its protons, neutrons, and electrons.