Question

Using the choices below, which is the complete symbol for the isotope that has the following subatomic particles: 19 protons, 21 neutrons, and 18 electrons.

(A: 40 19 K -1)
(B: 40 21 Sc +1)
(C: 38 19 K +1)
(D: 40 19 K +1)
(E: 39 18 Ar +1)

a. A
b. B
c. C
d. D
e. E​

Answer 1

Option D. ⁴⁰₁₉K⁺¹

Step-by-step explanation:

The following data were obtained from the question:

Proton number = 19

Neutron number = 21

Electron number = 18

Complete symbol of isotope =.?

Next, we shall determine the atomic number of the isotope. This is illustrated below:

Atomic number of an element is simply the number of protons in the atom of the element. Thus,

Atomic number = proton number

Proton number = 19

Therefore,

Atomic number = proton number = 19

Since the atomic number of the isotope is 19, the isotope is simply potassium with symbol K.

Next, we shall determine the mass number of the isotope. This can be obtained as follow:

Proton number = 19

Neutron number = 21

Mass number =.?

Mass number = Proton + Neutron

Mass number = 19 + 21

Mass number = 40

Next, we shall determine the charge on the isotope. This can be obtained as follow:

Proton number = 19

Electron number = 18

Charge =.?

Charge = Proton – Electron

Charge = 19 – 18

Charge = +1

Summary:

Atomic number = 19

Mass number = 40

Symbol = K

Charge = +1

Complete symbol = ⁴⁰₁₉K⁺¹