What is the relationship between atomic number and electron configuration?

The atomic number of an element determines its electron configuration, as it equals the number of electrons in a neutral atom.

The atomic number, also known as the proton number, is a fundamental property of an atom. It is denoted by the letter 'Z' and it represents the number of protons in the nucleus of an atom. In a neutral atom, the number of protons is equal to the number of electrons. Therefore, the atomic number also indicates the number of electrons in an atom.

Electron configuration refers to the distribution of electrons in an atom's atomic orbitals. It is determined by the Aufbau principle, the Pauli exclusion principle, and Hund's rule. The Aufbau principle states that electrons occupy the lowest energy level first. The Pauli exclusion principle states that each atomic orbital can hold a maximum of two electrons with opposite spins. Hund's rule states that electrons will occupy all the orbitals of a sublevel singly before pairing up.

The atomic number is directly related to the electron configuration. For example, hydrogen has an atomic number of 1, which means it has one electron. This electron is found in the 1s orbital, so the electron configuration of hydrogen is 1s¹. Helium has an atomic number of 2, meaning it has two electrons. Both of these electrons are found in the 1s orbital, so the electron configuration of helium is 1s².

In summary, the atomic number of an element is a key determinant of its electron configuration. By knowing the atomic number, one can predict the electron configuration of an atom, which is crucial in understanding the chemical behaviour and properties of the element.