To calculate the atomic mass of a compound based on its formula, you need to consider the atomic masses of the individual elements and the number of atoms of each element present in the compound. Here's a step-by-step guide:
Start by writing down the chemical formula of the compound. For example, let's use water (H2O).
Determine the atomic masses of the elements in the formula. You can find the atomic masses of elements on the periodic table. For water, the atomic mass of hydrogen (H) is approximately 1.01 amu, and the atomic mass of oxygen (O) is approximately 16.00 amu.
Count the number of atoms of each element in the formula. In water (H2O), there are two hydrogen atoms and one oxygen atom.
Multiply the atomic mass of each element by the number of atoms present in the compound.
For hydrogen (H): Atomic mass of hydrogen (H) = 1.01 amu Number of hydrogen atoms (H) = 2 Total mass contribution from hydrogen = Atomic mass of hydrogen (H) x Number of hydrogen atoms (H)
Total mass contribution from hydrogen = 1.01 amu x 2 = 2.02 amu
For oxygen (O): Atomic mass of oxygen (O) = 16.00 amu Number of oxygen atoms (O) = 1 Total mass contribution from oxygen = Atomic mass of oxygen (O) x Number of oxygen atoms (O)
Total mass contribution from oxygen = 16.00 amu x 1 = 16.00 amu
Add up the mass contributions from each element to obtain the total atomic mass of the compound.
Total atomic mass of water (H2O) = Total mass contribution from hydrogen + Total mass contribution from oxygen
Total atomic mass of water (H2O) = 2.02 amu + 16.00 amu = 18.02 amu
Therefore, the atomic mass of water (H2O) is approximately 18.02 amu.
You can apply this method to calculate the atomic mass of any compound by considering the atomic masses of the elements and the number of atoms present in the formula.