elektronhéj

An elektronhéj, or electron shell, is a region around the nucleus of an atom where electrons are most likely to be found. These shells are quantized, meaning electrons can only occupy specific energy levels within these regions. Think of them as distinct orbits or layers where electrons reside.

The shells are numbered sequentially, starting with n=1 for the innermost shell, closest to the nucleus. As the number 'n' increases, the shells become further from the nucleus and have higher energy. Each electron shell can hold a specific maximum number of electrons. The first shell (n=1) can hold up to 2 electrons, the second shell (n=2) up to 8, the third shell (n=3) up to 18, and so on, following the formula 2n^2.

The arrangement of electrons in these shells, known as electron configuration, determines an atom's chemical properties. Electrons in the outermost shell, called valence electrons, are particularly important as they participate in chemical bonding. The filling of electron shells follows specific rules, such as the Aufbau principle, Hund's rule, and the Pauli exclusion principle, which dictate how electrons occupy the available orbitals within each shell. Understanding electron shells is fundamental to comprehending atomic structure and chemical behavior.