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 ...

118 Elements and Their Symbols and Atomic Numbers ... which is based on atomic number rather than atomic mass. This arrangement was established by the British physicist Henry Moseley in 1913 ...

For example, the mass number of both argon atoms and calcium atoms is 40. The atomic number of a sodium atom is 11 and its mass number is 23. Calculate the number of protons, neutrons and ...

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 ...