Question

Calculate the total mass of the protons and electrons in 19 9F. Use 1.007825 amu as the mass of 11H (mass of a proton and an electron). Express your answer in atomic mass units to 6 significant figures.

Answer 1

Explanation:

Atomic mass means the sum of total number of protons and neutrons present in an atom.

When an atom is neutral then number of protons equal the number of electrons.

Mass of a proton equals to 1.007276 u, mass of neutron equals to 1.008664 u.

For example, in a $^{19}_{9}F$ atom there are total 9 protons and number of neutrons is 19 - 9 = 10.

Since, it is a neutral atom so number of electrons will also be 9.

So, total mass will be calculated as follows.

                  Total mass = 9 (mass of electron + mass of proton)

                                      = 9 (1.007825 u)

                                      = 9.07043 u

Therefore, we can conclude that total mass of protons and electrons in $^{19}_{9}F$ is  9.07043 u.