Symbol: A one or two-letter abbreviation used ... which is based on atomic number rather than atomic mass. This arrangement was established by the British physicist Henry Moseley in 1913, who ...

The atomic number is shown below the chemical symbol, and the mass number is shown above. In this example the atomic number is 17 and the mass number is 35. This means that each of these atoms has: ...

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 allows scientists to discern trends in ...

The full chemical symbol for an element shows its nucleon ... work out the number of neutrons by subtracting the atomic number from the mass number. In this example, it is 35 – 17 = 18 neutrons.