The molecular mass of a molecule is just the sum of the masses of each atom in it. So if water has a mass of 18, and hydrogen has a mass of 1, and there are two hydrogens and one oxygen in water (it has formula H2O), than oxygen must weigh 16. That is:
18 - (2*1) = 16
You can also look at a Periodic Table, and it will tell you the mass of every element without doing any calculations! See the Web Links to the left of the answer.
Atomic mass
On the periodic table each element will have 2 numbers. One will be a whole number going from 1 hydrogen to 113 or so. This is the atomic number which is the number of protons it has. There will also be a number with a few decimal places. Carbon has a atomic number of 6 (as it is element number 6 and has 6 protons.) and an atomic mass of 12.011. The atomic mass is the average mass of a an atom for Carbon 99% of the atoms have a mass 12 (6 protons and 6 neutrons) and 1% has a mass of 13 the average of the two (0.99 X 12) + (0.01 X 13) = 12.011
The atomic mass (or weight) of silver is 107.8682 amu (atomic mass units)
The atomic mass number of aluminum is 27. The atomic mass of aluminum is 26.98115386
Cobalt has an atomic mass of 58.933195(5) while nickel has an atomic mass of 58.6934(4). Nickel has the lower atomic mass.
Atomic no.=no. of protons Atomic mass=no. of protons+no. of neutrons Hence, atomic mass is greater
The atomic mass is the mass of a molecule, atomic particle or sub-atomic particle.
Atomic mass
On the periodic table each element will have 2 numbers. One will be a whole number going from 1 hydrogen to 113 or so. This is the atomic number which is the number of protons it has. There will also be a number with a few decimal places. Carbon has a atomic number of 6 (as it is element number 6 and has 6 protons.) and an atomic mass of 12.011. The atomic mass is the average mass of a an atom for Carbon 99% of the atoms have a mass 12 (6 protons and 6 neutrons) and 1% has a mass of 13 the average of the two (0.99 X 12) + (0.01 X 13) = 12.011
The atomic mass (or weight) of silver is 107.8682 amu (atomic mass units)
The atomic mass number of aluminum is 27. The atomic mass of aluminum is 26.98115386
Cobalt has an atomic mass of 58.933195(5) while nickel has an atomic mass of 58.6934(4). Nickel has the lower atomic mass.
The atomic mass of arsenic is approximately 74.92 atomic mass units.
The atomic mass of potassium is approximately 39.10 atomic mass units.
== == Atomic Mass: 54.93805 amu
Sulfur has an atomic mass of approximately 32.06 atomic mass units.
The atomic mass unit is used to express the measure of the atomic mass.