原子

• Reading: げんし
• Romaji: genshi
• Kanji breakdown: 原 (gen) — original, fundamental; 子 (shi) — child, element, particle
• Pronunciation: /geɴ.ɕi/

Meaning

Atom. The smallest unit of a chemical element that retains the properties of that element.

A fundamental chemistry and physics noun. The 子 (shi) suffix here means 'particle' (as in 分子, 電子, 遺伝子). Common collocations include 原子番号 (genshi bangou, atomic number), 原子核 (genshikaku, atomic nucleus), and 原子力 (genshiryoku, atomic/nuclear power). Also appears in 原子爆弾 (genshi bakudan, atomic bomb), often shortened to 原爆 (genbaku).

Examples

1. すべての物質は原子からできている。 All matter is made up of atoms.
2. 水分子は二つの水素原子と一つの酸素原子から構成される。 A water molecule is made up of two hydrogen atoms and one oxygen atom.
3. 原子の構造を理解することは化学の基本だ。 Understanding the structure of atoms is fundamental to chemistry.

Usage Guide

Context: chemistry, physics, education

Tone: neutral

Origin & History

From Sino-Japanese: 原 (gen, original/fundamental) + 子 (shi, particle/element). Literally 'fundamental particle' — the basic building block of matter. Coined as a translation of the Greek-derived 'atomos' (indivisible).

Cultural Context

Era: Modern

Generation: All ages

Social background: Universal