Answer:
Explanation:
Given parameters:
Mass of oxygen atom = 15.994914amu
Mass of a proton = 1.00728amu
Mass of a neutron = 1.00866amu
Unknown:
Mass defect = ?
From the periodic table, the number of the elementary particles in a neutral Oxygen atom is given below:
Number of protons = 8
Number of neutrons = 8
Number of electrons = 8
Solution
The mass defect examines the difference between the actual mass of an atom and sum of masses of the nucleons.
The mass of an atom is concentrated in the nucleus which contains protons and neutrons. Electrons have little to no weight compared with the nucleons.
To calculate the mass defect, we first know the mass of the nucleons first:
1 proton has a mass of 1.00728amu
8 protons will weigh: (8 x 1.00728)amu = 8.05824amu
For the neutrons:
1 neutron has a mass of 1.00866amu
8 neutrons will weigh: (8 x 1.00866)amu = 8.06928amu
Mass of the nucleons = mass of protons + mass of neutrons
= 8.05824amu + 8.06928amu
= 16.12752amu
The mass defect = mass of the nucleons - mass of the atom
= 16.12752amu - 15.994914amu
= 0.132606amu ≅ 0.13261amu to 5 decimal places
