Electrons in atoms

Electrons in Atoms

Basic Concepts

• Atoms are composed of three fundamental particles: protons, neutrons, and electrons.
• Electrons are subatomic particles that carry a negative charge. They are located in the space outside the nucleus of an atom.
• The number of electrons in an atom is equal to the number of protons in its nucleus. This balance of charges maintains the atom’s neutral status.

Orbital Structures

• Electrons in atom are found in regions called orbitals.
• An orbital can be visualised as a cloud-like region around the nucleus where there is a high probability of finding an electron.
• Each orbital can accommodate a maximum of two electrons.

Energy Levels

• In an atom, orbitals are grouped in shells or energy levels. Each shell represents a different energy level, with the first shell being the lowest.
• Shells closer to the nucleus (lower shells) have less energy than the shells further away (higher shells).

Electron Fill Order

• The placement of electrons in shells follows the Aufbau principle, electrons occupy the lowest energy orbitals available.
• The first shell (closest to the nucleus) is filled first, followed by the second, and so on.

Electron Configuration

• The distribution of electrons among the orbitals of an atom is known as the electron configuration.
• Electron configuration has implications for an atom’s stability, chemical reactivity, and magnetic properties.

Valence Electrons

• The electrons in the outermost shell of an atom are called its valence electrons.
• Valence electrons are instrumental in forming chemical bonds with other atoms.

Electron Spin

• Each electron in an atom is said to spin, giving it a spin quantum number.
• The Pauli Exclusion Principle states that no two electrons in an atom can have the same set of four quantum numbers, meaning no two electrons can be in the same state. This results in electrons pairing up in orbitals with opposite spins.