Question

An interplanetary probe returns to Earth with soil samples. The atoms in the sample are sorted by their number of protons. A new element is discovered! The new element has 120 protons. 20.0% of these new atoms have 120 neutrons, and the remaining 80.0% have 110 neutrons. They decide to call the new element Bolognium, Bo. What AVERAGE atomic mass should the scientists report in amu? Enter your answer below to the nearest WHOLE NUMBER with no units.

Answer 1

Answer is: the average atomic mass is 232.

ω₁ = 20% ÷ 100%.

ω₁ = 0.20.

ω₂ = 80% ÷ 100%.

ω₂ = 0.80.

Ar₁ = 120 (number of protons) + 120 (number of neutrons).

Ar₁ = 240.

Ar₂ = 120 + 110 .

Ar₂ = 230.

Average atomic mass of atoms of bolognium =  

Ar₁ · ω₁ + Ar₂ · ω₂.  

Average atomic mass of atoms of bolognium =  240 · 0.2 + 230 · 0.8.  

Average atomic mass of atoms of bolognium = 48 + 184.  

Average atomic mass of atoms of bolognium = 232.