If 79Br is one of the isotopes, what is the other isotope given the atomic mass of bromine is approximately 80 amu?

With no more information than that I would guess that

Two isotopes so we average them out.
I would guess that 80 = (79 + x)/2
160 = 79 + x
x = about 160 - 79 = about 81 for the other isotope.

Well, I must say, Bromine is quite the "brilliant" element! The atomic mass of bromine is approximately 80 amu, and since 79Br is known to be one of its isotopes, the other isotope must be 81Br. It seems Bromine likes to keep it odd with its isotopes!

To determine the other isotope of bromine, we need to subtract the atomic mass of 79Br from the total atomic mass of bromine, which is approximately 80 amu.

Let X represent the other isotope of bromine.

Total atomic mass of bromine = mass of 79Br + mass of X

80 amu = mass of 79Br + mass of X

Rearranging the equation:

mass of X = 80 amu - mass of 79Br

Substituting the known atomic mass of 79Br:

mass of X = 80 amu - 79 amu

mass of X ≈ 1 amu

Therefore, the other isotope of bromine, apart from 79Br, has an atomic mass of approximately 1 amu.

To find the other isotope of bromine, we need to subtract the mass of the known isotope (79Br) from the total atomic mass of bromine (approximately 80 amu).

The atomic mass of bromine is the weighted average of the masses of its isotopes, taking into account their relative abundance.

Let's denote the mass of the other isotope as x. We have the following equation:

(79 amu)(abundance of 79Br) + (x amu)(abundance of the other isotope) = 80 amu

We know that the abundance of isotopes can vary, but for simplicity, let's assume that each isotope has an equal abundance (50% each). Therefore, we can rewrite the equation with the abundance values:

(79 amu)(0.5) + (x amu)(0.5) = 80 amu

Now we can solve the equation for x:

(39.5 amu) + (0.5x amu) = 80 amu
0.5x amu = 40.5 amu
x amu = 81 amu

Therefore, the other isotope of bromine is 81Br.