Question

Write the isotopic symbol for the following (show your work) a) An isotope of iodine whose atoms have 78 neutrons b) An isotope of cesium whose atoms have 82 neutrons c) An isotope of strontium whose atoms have 52 neutrons

Answer 1

For a: The isotopic representation of iodine is
`_(53)^(131)\textrm{I}`

For b: The isotopic representation of cesium is
`_(55)^(137)\textrm{Cs}`

For c: The isotopic representation of strontium is
`_(38)^(52)\textrm{Sr}`

Step-by-step explanation:

The isotopic representation of an atom is:
`_Z^A\textrm{X}`

where,

Z = Atomic number of the atom

A = Mass number of the atom

X = Symbol of the atom

• For a:

We are given:

Number of neutrons = 78

Atomic number of iodine = 53 = Number of protons

Mass number = 53 + 78 = 131

Thus, the isotopic representation of iodine is
`_(53)^(131)\textrm{I}`

• For b:

We are given:

Number of neutrons = 82

Atomic number of cesium = 55 = Number of protons

Mass number = 55 + 82 = 137

Thus, the isotopic representation of cesium is
`_(55)^(137)\textrm{Cs}`

• For c:

We are given:

Number of neutrons = 52

Atomic number of strontium = 38 = Number of protons

Mass number = 38 + 52 = 90

Thus, the isotopic representation of strontium is
`_(38)^(52)\textrm{Sr}`