Charge number

The charge number of the atomic nucleus (synonyms: atomic number , atomic number , the ordinal number of the chemical element ) is the number of protons in the atomic nucleus. The charge number is equal to the charge of the nucleus in units of the elementary charge and at the same time is equal to the ordinal number of the corresponding nucleus of the chemical element in the periodic table .

The term “atomic” or “ordinal” number is usually used in atomic physics and chemistry , while the equivalent term “charge number” is used in nuclear physics . In a non-ionized atom, the number of electrons in the electron shells coincides with the charge number.

The charge number is usually denoted by the letter Z ( from it. Atom z ahl - "atomic number", "atomic number" ^[1] ) . Nuclei with the same charge number but different mass number A (which is equal to the sum of the number of protons Z and the number of neutrons N ) are different isotopes of the same chemical element, since it is the nuclear charge that determines the structure of the electron shell of an atom and, therefore, its chemical properties.