A se ion has a mass number of 77 and a charge of −2
. Determine the number of neutrons, protons, and electrons in this ion.

1. Neutron number = 43

2. Proton number = 34

3. Electron number = 36

Explanation:

From the question given above, the following data were obtained:

Mass number = 77

Charge of ion = –2

1. Determination of the number of neutron.

Mass number of Se = 77

Atomic number = 34

Neutron number =?

NOTE: Atomic number = proton number

Mass number = Proton + Neutron

77 = 34 + Neutron

Collect like terms

77 – 34 = Neutron

Neutron number = 43

2. Determination of the proton number.

The atomic number of an element is simply defined as the number of protons in the atom of the element. Mathematically,

Atomic number = Proton number

Atomic number of Se = 34

Therefore, the proton number of Se²¯ is 34.

NOTE: The atomic number does not change be it atom, ion or molecule. It remains the same.

3. Determination of electron number.

Charge of ion = –2

Proton number = 34

Electron number =?

Proton – Electron = Charge

34 – Electron = –2

Rearrange

34 + 2 = Electron

36 = Electron

Electron number = 36

the answer for sodium is 0.186

the answer for rubidium is 0.251

if the temperature drops and becomes cool

then the atmosphere can be freezing as the water vapor in the air is at maximum (100%) and can be severely cold

also can be snowing lightly as the moisture in the air will start to solidify

and btw this is not chemistry but