極性

• Reading: きょくせい
• Romaji: kyokusei
• Kanji breakdown: 極 (kyoku) — pole, extreme end; 性 (sei) — property, nature
• Pronunciation: /kjoː.kɯ.seː/

Meaning

Polarity; the separation of electric charge, leading to a molecule or bond having a positive and a negative end.

A chemistry term describing the unequal distribution of electrons in a bond or molecule, resulting in partial charges. Polar molecules (極性分子) like water (水) have distinct positive and negative ends, making them excellent solvents for ionic compounds. Non-polar molecules (無極性分子) like oils do not mix with water. 極性 also appears in physics (electrical polarity, magnetic polarity) and biology (cell polarity — 細胞極性). The concept is foundational to understanding solubility, intermolecular forces, and chemical reactivity.

Examples

1. 水分子は極性が高く、イオン結合性の物質をよく溶かすことができる。 Water molecules have high polarity and can dissolve ionic substances well.
2. 極性溶媒は極性物質を溶かし、無極性溶媒は無極性物質を溶かすという原則がある。 There is a principle that polar solvents dissolve polar substances, and non-polar solvents dissolve non-polar substances.
3. 共有結合の極性は、結合している原子の電気陰性度の差によって決まる。 The polarity of a covalent bond is determined by the difference in electronegativity of the bonded atoms.

Usage Guide

Context: chemistry, physics, biology, materials science

Tone: technical, academic

Origin & History

Sino-Japanese compound: 極 (kyoku) — pole, extreme end + 性 (sei) — property, nature. 極 is used in 北極 (North Pole), 南極 (South Pole), and 電極 (electrode), all carrying the sense of an extreme or terminal end.

Cultural Context

Era: Meiji-Modern

Generation: Adult

Social background: Educated