Question

Which orbital will be filled first in each set? State the reason
a) 2p (or) 3s b) 3d (or) 4

Answer 1

I hope it helps you my friend

Answer 2

Aufbau principle

Explanation:

• The principle of construction determines how electrons fill the atomic orbitals of ground-state atoms. According to this theory, electrons are injected into atomic orbitals in the order of increasing orbital energy. According to the Aufbau principle, the lowest energy atomic orbitals are occupied first, followed by the higher energy levels.
• The word 'Aufbau' has German roots and essentially translates to 'build up' or 'construct.' The order in which atomic orbitals are filled is depicted in the diagram below. The primary quantum number is ‘n,' and the azimuthal quantum number is ‘l.'
• The Aufbau principle can be used to figure out where electrons are in an atom and what energy levels they correspond to. Carbon, for example, has six electrons and has the electrical structure 1s22s22p2.
• It's vital to remember that each orbital can only store two electrons (as per the Pauli exclusion principle). In addition, the way electrons are filled into orbitals in a single subshell must adhere to Hund's rule, which states that every orbital in a given subshell must be single-occupied by electrons before any two electrons pair up in an orbital.    
• The Aufbau principle states that electrons will inhabit the lowest-energy orbitals first. This means that electrons can only enter higher-energy orbitals after lower-energy orbitals have been entirely filled.
• The (n+l) rule can be used to establish the sequence in which the energy of orbitals grows, with the sum of the primary and azimuthal quantum numbers determining the orbital's energy level.  
• Lower orbital energies correspond to lower (n+l) values. When two orbitals have the same (n+l) values, the orbital with the lower n value is said to have less energy.
• The electrons are filled in the orbitals in the following order:  1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p, etc.