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

The symbol of ion will be:

The symbol of ion will be:

The symbol of ion will be:

The symbol of ion will be:  

Explanation:

The symbol of an ion of an element is written as:

Where:

A = Mass number of the atom

Z = Atomic number of the atom

X = Symbol the atom

C = Charge on the atom

Given:

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

To find:

The symbols of given ions

Solution:

a)

Charge on the ion = C = 3+

Number of electrons in the ion = 28

Number of electrons in ion's parent atom = 28 +3 = 31

Number of electrons in parent atom = Number of proton in ion/ paarent atom

= 31 = 31

Atomic number = Number of protons

Atomic number of the ion = Z = 31

Mass number of ion = A = 71

The element with atomic number 31 is gallium with the chemical symbol Ga, so the symbol of ion will be:

b)

Charge on the ion = C = ?

Number of electrons in the ion = 36

Number of protons in the ion = 35

Number of neutrons = 45

Number of electrons in parent atom = Number of protons in ion/ parent atom

= 35 = 35

Atomic number = Number of protons

Atomic number of the ion = Z = 35

Number of electrons in ion's parent atom = Number of protons in the ion = 35

Charge on the ion = C = 36 - 35 = 1-

Mass number of ion = Number of protons + Mass of neutrons

A = 35 + 45 = 80

The element with atomic number 35 is bromine with the chemical symbol Br, so the symbol of ion will be:

c)

Charge on the ion = C = 4+

Number of electrons in the ion = 86

Number of electrons in ion's parent atom = 86+4 = 90

Number of electrons in parent atom = Number of protons in ion/ parent atom

= 90= 90

Atomic number = Number of protons

Atomic number of the ion = Z = 90

Number of neutrons = 142

Mass number of ion = Number of protons + Mass of neutrons

A = 90+ 142 = 232

The element with atomic number 90 is thorium with the chemical symbol Th, so the symbol of ion will be:

d)

Charge on the ion = C = 2+

Atomic number of the ion = Z = 38

Mass number of ion = A = 87

The element with atomic number 38 is strontium with chemical symbol Sr, so the symbol of ion will be:

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Explanation:

(a)

If the ion has 28 electrons and a 3+ charge, it normally has 31 electrons. It must also have 31 protons. Atom 31 is gallium.

(b)

If the ion has 35 protons, it normally has 35 electrons. It has 36 electrons, so it has a negative charge.  Atom 35 is bromine.

A = p + n = 35 + 45 = 80, so the isotopic mass number is 80

\text{The symbol for the ion is }\boxed{\mathbf{_{35}^{80}\textbf{Br}^{-}}}

(c)

If the ion has 86 electrons and a charge of 4+, it normally has 90 electrons. It must also have 90 protons. Atom 90 is thorium.

A = p + n = 90 + 142 = 232, so the isotopic mass number is 232.

(d)

If the ion has 38 protons, it is strontium.