Question

If an isotope of an element has 33 neutrons and a mass number of 64, how many electrons must it have?

Answer 1

The mass number is the sum of the protons and neutrons
64 = #protons + #neutrons
Find the number of protons given the number of neutrons
64 = #protons + 33
#protons = 31
In a neutral element (such as this), the number of electrons equals the number of protons
#electrons = #protons
#electrons = 31

Answer 2

The isotope must have 31 electrons

Step-by-step explanation:

• Mass number = (number of neutrons)+(number of protons)
• Here, mass number of element is 64 and number of neutrons is 33
• So, number of protons i the element = (mass number)-(number of neutrons) = (64)-(33) = 31
• Isotope of an element remain present in neutral form.
• So, number of protons should be equal to number of electrons in that isotope. Because proton has +1 charge and electron has -1 charge
• So, the isotope must have 31 electrons.