Answer:
207.89g
Explanation:
The formula of the compound is:
Fe₂S₃
Find the molar mass of the compound;
Atomic mass of Fe = 55.845g/mol
S = 32.065g/mol
Now;
Molar mass of Fe₂S₃ = 2 (55.845) + 3 (32.065)
= 207.89g
Answer:
three valence electrons
Explanation:
Gallium has three electrons in the outer energy level and therefore has three valence electrons. The identification of valence electrons is vital because the chemical behavior of an element is determined primarily by the arrangement of the electrons in the valence shell.
Great question, but I believe you are mixing up atomic number with mass number. Assuming you are, 12.011 amu is the average mass of a carbon atom. For carbon, it can come in three forms: carbon-12, carbon-13, carbon-14. The number following carbon is the mass number of that particular carbon "isotope". The reason the average is so close to 12 is because carbon-12 is by far the most common, so the average should be (and is) very close to 12. Therefore, 12.011 is a weighted average of all carbon molecules, and carbon-14 is a particular carbon molecule that weighs 14 amu.
