Symbol: A one or two-letter abbreviation used to represent the element. Atomic number: The number of protons in the nucleus of an atom of the element ... than atomic mass. This arrangement ...

For example, the atomic number of sodium is 11. Every sodium atom has 11 protons and 11 electrons. It has 11 positive charges and 11 negative charges. The mass number of an atom is its total ...

according to increasing atomic number. Scientists use the periodic table to quickly refer to information about an element, like atomic mass and chemical symbol. The periodic table’s arrangement also ...

This symbol tells you that the chlorine atom has 17 protons ... work out the number of neutrons by subtracting the atomic number from the mass number. In this example, it is 35 – 17 = 18 ...