Question

Write the symbol for each of the following ions:

(a) the ion with a 3+ charge, 28 electrons, and a mass number of 71
(b) the ion with 36 electrons, 35 protons, and 45 neutrons
(c) the ion with 86 electrons,142 neutrons, and a 4+ charge
(d) the ion with a 2+ charge, atomic number 38, and mass number 87

Answer 1

a)
`_(31)^(71)\textrm {P^(3+)}`

b)
`_(35)^(80)\textrm {Br^(-)}`

c)
`_(90)^(232)\textrm {Th^(4+)}`

d)
`_(38)^(87)\textrm {Sr^(2+)}`

Step-by-step explanation:

For neutral atoms:

Atomic Number (Z)= number of protons = number of electrons

Mass number (A) = number of protons + number of neutrons

For ions with positive net charge:

Number of protons = Z + net charge

For ions with negative net charge:

Number of protons= Z - net charge

a) A = 71, Charge = +3

Number of electrons = 28

Number of protons = 28 +3 =31

`_(31)^(71)\textrm {P^(3+)}`

b) A = 35, Z = 45+35=80, Charge = -1

Number of protons =35

Number of neutrons = 45

Number of electrons = 36

Charge = Number of protons- Number of electrons =35-36 = -1

`_(35)^(80)\textrm {Br^(-)}`

c) Charge = +4

Number of electrons = 86

Number of protons = Z = 86+4 = 90

mass number = A = 90+142 = 232

`_(90)^(232)\textrm {Th^(4+)}`

d) Charge = +2

Atomic number = Number of protons = Z = 38

mass number = A = 87

`_(38)^(87)\textrm {Sr^(2+)}`