how are electrons organized in an atom of potassium

Atomic Structure and Electron Configuration

This entry details the arrangement of electrons within an atom, focusing on the principles governing electron shell occupancy and the specific example of a potassium atom.

Electron Shells and Subshells

Electrons reside in distinct energy levels, or shells, surrounding the atom's nucleus. These shells are designated by principal quantum numbers (n = 1, 2, 3, etc.), with higher n values indicating greater distance from the nucleus and higher energy. Each shell can contain a maximum number of electrons, determined by the formula 2n². Shells are further divided into subshells (s, p, d, f), each capable of holding a specific number of electrons (s: 2, p: 6, d: 10, f: 14). Electrons fill these subshells according to the Aufbau principle and Hund's rule.

The Aufbau Principle and Hund's Rule

The Aufbau principle states that electrons first fill the lowest energy levels available. Hund's rule dictates that electrons individually occupy each orbital within a subshell before pairing up. Orbitals within a subshell have equal energy.

Electron Configuration of Potassium

Potassium (K) has an atomic number of 19, meaning it possesses 19 protons and 19 electrons in a neutral atom. Following the Aufbau principle and Hund's rule, the electron configuration of potassium is 1s²2s²2p⁶3s²3p⁶4s¹. This indicates that:

  • The first shell (n=1) contains 2 electrons in the 1s subshell.
  • The second shell (n=2) contains 8 electrons (2 in the 2s and 6 in the 2p).
  • The third shell (n=3) contains 8 electrons (2 in the 3s and 6 in the 3p).
  • The fourth shell (n=4) contains 1 electron in the 4s subshell.

Valence Electrons and Chemical Reactivity

The outermost shell electrons, known as valence electrons, are crucial in determining an atom's chemical behavior. Potassium possesses one valence electron in its 4s subshell, making it highly reactive and prone to losing this electron to achieve a stable, filled outer shell configuration.

Orbital Diagrams

A visual representation of electron configuration using orbital diagrams illustrates the arrangement of electrons within each subshell, showing both the shell and subshell occupancy and electron spin.