Summary
Highlights
The video revisits the definition of an orbital as a description of the probability of finding an electron. It reviews the S, P, D, and F subshells, noting the number of orbitals within each (s: 1, p: 3, d: 5, f: 7) and the maximum number of electrons each can hold (s: 2, p: 6, d: 10, f: 14).
The video begins discussing electron configurations with a neutral hydrogen atom. With one proton and one electron, the electron resides in the lowest energy level, specifically the 1s subshell. Its configuration is 1s1.
For a neutral helium atom with two electrons, both electrons occupy the 1s subshell, as it can hold up to two electrons. The electron configuration for helium is 1s2.
Lithium, with three electrons, fills the 1s subshell with two electrons (1s2) and then places its third electron in the next available, lowest energy subshell, which is the 2s subshell (2s1). Beryllium, with four electrons, follows a similar pattern, filling the 1s and 2s subshells entirely (1s2 2s2).
Boron, with five electrons, fills the 1s and 2s subshells, then places its fifth electron in the 2p subshell (1s2 2s2 2p1). Carbon, with six electrons, adds another electron to the 2p subshell (1s2 2s2 2p2). The p subshell can hold up to six electrons, allowing for further filling in this subshell for subsequent elements.
To simplify writing electron configurations for larger atoms, the noble gas configuration is introduced. This shorthand uses the symbol of the preceding noble gas in brackets to represent the filled inner shells, followed by the configuration of the valence electrons. For example, carbon's configuration can be written as [He] 2s2 2p2, where [He] represents 1s2.