Question

1. give the symbol and number of neutrons in one atom of: (to get “mass number”, you must round the “atomic mass” to the nearest whole number) show your calculations. barium ___________ bismuth _________ carbon _________ hydrogen _________ fluorine _________ magnesium _________ europium _________ mercury ___________

Explanation:

Step1: Recall the atomic - number and atomic - mass relationship

The number of neutrons $n$ in an atom is given by $n = A - Z$, where $A$ is the mass number (rounded atomic mass) and $Z$ is the atomic number. We need to look up the atomic numbers and atomic masses from the periodic table.

Step2: For Barium ($Ba$)

Atomic number $Z = 56$, atomic mass $\approx137.33$. Rounding the atomic mass, $A = 137$. Then the number of neutrons $n=137 - 56=81$. Symbol: $^{137}_{56}Ba$.

Step3: For Carbon ($C$)

Atomic number $Z = 6$, atomic mass $\approx12.01$. Rounding the atomic mass, $A = 12$. Then the number of neutrons $n=12 - 6 = 6$. Symbol: $^{12}_{6}C$.

Step4: For Fluorine ($F$)

Atomic number $Z = 9$, atomic mass $\approx18.998$. Rounding the atomic mass, $A = 19$. Then the number of neutrons $n=19 - 9=10$. Symbol: $^{19}_{9}F$.

Step5: For Europium ($Eu$)

Atomic number $Z = 63$, atomic mass $\approx151.96$. Rounding the atomic mass, $A = 152$. Then the number of neutrons $n=152 - 63 = 89$. Symbol: $^{152}_{63}Eu$.

Step6: For Bismuth ($Bi$)

Atomic number $Z = 83$, atomic mass $\approx208.98$. Rounding the atomic mass, $A = 209$. Then the number of neutrons $n=209 - 83=126$. Symbol: $^{209}_{83}Bi$.

Step7: For Hydrogen ($H$)

Atomic number $Z = 1$, atomic mass $\approx1.008$. Rounding the atomic mass, $A = 1$. Then the number of neutrons $n=1 - 1=0$. Symbol: $^{1}_{1}H$.

Step8: For Magnesium ($Mg$)

Atomic number $Z = 12$, atomic mass $\approx24.31$. Rounding the atomic mass, $A = 24$. Then the number of neutrons $n=24 - 12 = 12$. Symbol: $^{24}_{12}Mg$.

Step9: For Mercury ($Hg$)

Atomic number $Z = 80$, atomic mass $\approx200.59$. Rounding the atomic mass, $A = 201$. Then the number of neutrons $n=201 - 80=121$. Symbol: $^{201}_{80}Hg$.

Answer:

Barium: Symbol $^{137}_{56}Ba$, 81 neutrons
Carbon: Symbol $^{12}_{6}C$, 6 neutrons
Fluorine: Symbol $^{19}_{9}F$, 10 neutrons
Europium: Symbol $^{152}_{63}Eu$, 89 neutrons
Bismuth: Symbol $^{209}_{83}Bi$, 126 neutrons
Hydrogen: Symbol $^{1}_{1}H$, 0 neutrons
Magnesium: Symbol $^{24}_{12}Mg$, 12 neutrons
Mercury: Symbol $^{201}_{80}Hg$, 121 neutrons