Question

Identify the missing information for each atom or ion. Note that the atoms and ions are not necessarily neutral.

Answer 1

Answer :

(1) Number of neutrons:  44

Number of protons:  34

Number of electrons: 36

(2) Element symbol:  Ni

Number of protons:  29

Number of electrons: 28

(3) Element symbol:  Kr

Mass number:  78

Charge: 0

Explanation :

Atomic number : It is defined as the number of protons or number of electrons.

Atomic number = number of protons

Mass number : It is defined as the sum of number of protons and number of neutrons.

Number of neutrons = Mass number - Atomic number

Part 1:

Element = Se (selenium)

Mass number = 78

Atomic number = 34

Charge on Se = -2

Atomic number = Number of protons = 34

Number of electrons = Number of protons - charge = 34 - (-2) = 36

Number of neutrons = Mass number - Atomic number = 78 - 34 = 44

Part 2:

Mass number = 65

Number of neutrons = 36

Charge on Se = +1

Number of neutrons = Mass number - Atomic number

36 = 65 - Atomic number

Atomic number = 65 - 36 = 29

Atomic number = Number of protons = 29

Number of electrons = Number of protons - charge = 29 - (+1) = 28

The symbol of element is, Nickel (Ni)

Part 3:

Number of neutrons = 42

Number of protons = 36

Number of electrons = 36

Atomic number = Number of protons = 36

Number of neutrons = Mass number - Atomic number

42 = Mass number - 36

Mass number = 42 + 36 = 78

Number of electrons = Number of protons - charge

36 = 36 - charge

Charge = 0

The symbol of element is, Krypton (Kr)