Answer:
X is the chemical symbol of the element.
A is the mass number (number of protons neutrons).
Z is the atomic number (number of protons).
Explanation:
In stating the chemical representation of an element, the AZX symbol is used.
The symbol of the element may either come from its Latin or English name. For instance, the symbol of the element sodium, comes from its Latin name natrium (Na).
Its atomic number is the number of protons in the nucleus of the atom. For sodium, the atomic number is 11.
The mass number refers to the sum of the number of protons and neutrons in the atom. For sodium the mass number is 23.
Hence the AZX symbol for sodium is
23_11Na.
