Question

Determine the number of neutrons, protons, and electrons for a bromide ion that has a mass number of 79, and a charge of -1.

number of neutrons:
number of protons:
number of electrons:

Answer 1

`_(79)`
`Br^(-1)`

Protons 35

Neutrons 44

Electrons 36

Step-by-step explanation:

Bromine is element number 35, so it has 35 protons, by definition. Each proton is assigned an atomic mass of 1. So 35 protons contributes 35AMU (atomic mass units) to the total mass number. Electrons are assigned zero so that means that the rest of bromine's mass much come from neutrons (also at 1 AMU each).

Particle Number AMU Each Total AMU

Proton 35 1 35

Neutron X 1 1X

Electron 35 0 0 [35 in a neutral atom]

Total AMU = 35 + X = 79

X, the number of neutrons is = 44

A neutral bromine atom has equal numbers of protons and neutrons, in the case 35 each. But this is not a neutral atom - it has a charge of -1. This means it has one more electrons (-1 charge each) that it has protons (35), so it has 36 electrons.

`_(79)`
`Br^(-1)`

Particle Number AMU Each Total AMU Total Charge

Proton 35 1 35 + 35

Neutron 44 1 44

Electron 36 0 0 - 36

Total AMU = 79 -1

It has a net charge of -1 due to 36 electrons but only 35 protons.

Answer 2

An ion of platinum with a mass number of 195 contains 74 electrons. The number of protons is equal to its atomic number, which is 74, and the number of neutrons is 121.

Step-by-step explanation:

An ion of platinum with a mass number of 195 contains 74 electrons. To determine the number of protons and neutrons, subtract the number of electrons from the mass number. Therefore, the number of protons in the platinum ion is the same as its atomic number, which is 74. The number of neutrons is calculated by subtracting the number of protons from the mass number: 195 - 74 = 121 neutrons. As for the charge of the ion, it is not mentioned in the question.