Part 3 Reading the Atomic Number
- Read the periodic table according to the atomic number at the top center or top left of each element's box.
- Understand that the atomic number is the number of protons in the nucleus of a single atom of the element.
- Know that adding or removing protons would create a different element.
Correspondingly, what do the numbers mean on the elements?
The number above the symbol is the atomic mass (or atomic weight). This is the total number of protons and neutrons in an atom. The number below the symbol is the atomic number and this reflects the number of protons in the nucleus of each element's atom. Every element has a unique atomic number.
What is the number at the bottom of an element?
The full chemical symbol for an element shows its mass number at the top, and its atomic number at the bottom. This symbol tells you that the chlorine atom has 17 protons. It will also have 17 electrons, because the number of protons and electrons in an atom is the same.
What do the whole number on the periodic table represent?
Atomic number: The number of protons in an atom is referred to as the atomic number of that element. Individual atoms always have an integer number of atomic mass units; however, the atomic mass on the periodic table is stated as a decimal number because it is an average of the various isotopes of an element.