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An element symbol with mass number above and atomic number below, to its left.
Also known as: Nuclide notation, Numbers before an element
The two numbers to the left of an element symbol are its mass number above and atomic number below. The lower one is redundant — the element's name already fixes it — and it is written anyway because balancing a nuclear equation needs both visible.
States a nuclide's mass number as a superscript and its atomic number as a subscript, both to the left of the element symbol.
Contexts: Laboratory
Writes the atomic number even though the element symbol already determines it, because a nuclear equation is balanced by checking that both columns sum correctly on each side.
Contexts: Laboratory
Is contracted in speech and in text to the element name with the mass number after it, as carbon-14, which drops the redundant figure.
Contexts: Laboratory
One or two capital letters preceded by two numerals stacked vertically at the upper and lower left, the upper larger than the lower.