Question

Determine the mass number of a gold atom with 118 neutrons.

Answer 1

Step 1

Z = atomic number

A = mass number

n = number of neutrons

The next formula is used:

`n\text{ = A - Z}`

-----------------------

Step 2

Information provided:

Element = Gold => The atomic number (Z) for gold is 79

(Z is found in the periodic table)

n = 118 nutrons

-----------------------

Step 3

From step 1, A is found as follows:

n = A - Z

n + Z = A

118 + 79 = A

197 = A

Answer: The mass number (A) = 197