The sum of atomic masses refers to the total mass of all the atoms in a given sample or substance. It is calculated by adding up the atomic masses of all the individual atoms present.
To determine the sum of atomic masses, you need to know the number of atoms of each element in the sample and their respective atomic masses. The atomic masses of elements can be found on the periodic table, typically listed below the element's symbol.
Here's an example to illustrate the calculation:
Let's say you have a sample of water (H2O). To find the sum of atomic masses, you need to consider the atomic masses of two hydrogen atoms (H) and one oxygen atom (O).
Atomic mass of hydrogen (H): 1.008 u (approximately) Atomic mass of oxygen (O): 16.00 u (approximately)
Since there are two hydrogen atoms and one oxygen atom in water, the calculation would be as follows:
Sum of atomic masses = (2 * atomic mass of hydrogen) + (1 * atomic mass of oxygen) = (2 * 1.008 u) + (1 * 16.00 u) = 2.016 u + 16.00 u = 18.016 u
Therefore, the sum of atomic masses for water (H2O) is approximately 18.016 atomic mass units (u).