The electronic configuration of Cu(29) is an exceptional case due to exchange of energy and symmetrical distribution of electrons in orbital to acquire more stability.
copper has the atomic number 29, its electronic configuration is Cu (29)= 1s² 2s²2p⁶ 3s² 3p⁶ 3d¹º 4s¹. This is because half filled and fully filled shells are more stable, therefore it does not follow hund’s rule.
The atomic structure of an element refers to the constitution of its nucleus and the arrangement of the electrons around it. Primarily, the atomic structure of matter is made up of protons, electrons and neutrons.
Dalton proposed that every matter is composed of atoms that are indivisible and indestructible.
The following are the postulates of his theory:
Several atomic structures of an element can exist, which differ in the total number of nucleons.These variants of elements having a different nucleon number (also known as the mass number) are called isotopes of the element. Therefore, the isotopes of an element have the same number of protons but differ in the number of neutrons. For example, there exist three known naturally occurring isotopes of hydrogen, namely, protium, deuterium, and tritium.