Question

What is the first step to determine the sequence of filling electron configurations of an element?

Answer 1

To determine the sequence of filling electron configurations, start by figuring out the number of electrons in the atom and then use the Aufbau Principle to fill the electron orbitals beginning from the lowest energy level, following the order indicated by the periodic table.

Step-by-step explanation:

The first step to determine the sequence of filling electron configurations of an element is to determine the number of electrons that the atom has. Once this is known, one can begin to fill the electron orbitals starting with the lowest energy level. According to the Aufbau Principle, electrons are added one at a time to the lowest energy subshells available, following a specific order: 1s, 2s, 2p, 3s, and so on.

This process is guided by the shape of the periodic table, which provides a visual representation of the electron-filling order across different subshells. For example, hydrogen (H) and helium (He) have electron configurations of 1s¹ and 1s² respectively, aligning with the first row of the periodic table, where the n = 1 shell is filled. This pattern continues across the periodic table, reflecting the filling of subshells with electrons in a manner consistent with the energies of orbitals and subshells.

Answer 2

Basically, the arrangement of electrons in electronic configuration follows three principles:

1. Aufbau Principle
You start from the highest energy level to the lowest. The arrangement is: 1s<2s<2p<3s<3p<4s<3d<4p<5s<4d<5p<6s<4f<5d<6p<7s<5f<6d<7p.

2. Hund's Rule
Each box in the configuration can hold up to 2 electrons. This rule tells you to fill all boxes of one particular subshell with 1 electron first, before double occupying them.

3. Pauli's Exclusion Principle
This rule tells you that the two electrons in a box shall always have opposite spins, represented by one half-arrow up and one half-arrow down.