Mastering Electron Positions

Hund's Rule, the Pauli exclusion principle, and the Aufbau principle.

Orbitals are fixed locations where electrons are likely to be found within an atom. Their location is defined by their quantum number.

The first quantum number, n, represents the electron shell and gives the energy levels of the atomic structure.

The analogy of a hotel can be used to explain electron shells by comparing them to floors of the hotel. The lower the floor (i.e. the smaller the value of n), the lower the energy of that electron shell.

The second quantum number, l, represents the subshells within each electron shell. These subshells have different shapes depending on their energy level.

The third quantum number, ml, represents the number of orbitals per subshell. Each of these orbitals can hold exactly two electrons.

The first quantum number (n) represents the shell.

The second quantum number (l) represents the subshell.

The third quantum number (ml) represents the number of orbitals in a subshell.

The fourth quantum number (ms) represents the electron spin.

The Pauli exclusion principle states that no two electrons can have the exact same quantum numbers.

Hund's rule states that electrons will fall into empty orbitals of the same energy before electrons begin to pair up into the same orbital, and that these electrons falling into empty orbitals will all have the same spin value.

The Aufbau Principle states that electrons fill lower energy orbitals before moving to higher energy orbitals.

With these three rules, we can determine the order in which subshells and shells are filled, exactly how electrons fill each subshell, and how they fill a single orbital.

The Pauli exclusion principle states that no two electrons in an atom can have the exact same quantum numbers.

The fourth quantum number is ms, which gives the spin of an electron. It can come in a value of either 1/2 (spin-up) or -1/2 (spin-down).

Hund's rule states that electrons will fall into empty orbitals of the same energy before electrons begin to pair up into the same orbital. This helps determine the filling of orbitals in subshells containing multiple orbitals.

The Aufbau principle states that electrons will fill the lower energy level orbitals before moving to higher energy orbitals. It determines the filling order of subshells.

In general, the energy levels of orbitals increase with the first and second quantum numbers, which are the shell and the subshell.

According to the diagram provided, the subshells are filled in the order 1s, 2s, 2p, 3s, 3p, 4s, 3d, and so forth.