Wonderful! The first letter must be a capital letter, and the second letter must be a small letter. So, Pb is the correct way to write the symbol. By the way, Pb is the symbol for Lead.
We said that elements get their properties from their atoms. Mass (weight) is one property of elements.

According to Dalton, each atom has a mass. The mass of an object is nothing but the total mass of all its atoms. So, if an object has a mass of \(1 \, \mathrm{kg}\), it means that the total mass of all the atoms in that object is \(1 \, \mathrm{kg}\).