4 sentences

1. 这是一个氢原子。

   zhè shì yī gè qīng​yuán​zǐ.

   This is a hydrogen atom.

   Source: OpenSubtitles

2. 苯环上的氢原子可以发生取代反应。

   běn​huán shàng de qīng​yuán​zǐ kě​yǐ fā​shēng qǔ​dài fǎn​yìng.

   Hydrogen atoms on the benzene ring can undergo substitution reactions.

   Source: Dong Chinese Dictionary

3. 每个分子由两个氢原子和一个氧原子组成。

   měi gè fēn​zǐ yóu liǎng gè qīng​yuán​zǐ hé yī gè yǎng yuán​zǐ zǔ​chéng.

   Each molecule is composed of two hydrogen atoms and one oxygen atom.

   Source: Dong Chinese Dictionary

4. 每个水分子由两个氢原子和一个氧原子组成。

   měi gè shuǐ fēn​zǐ yóu liǎng gè qīng​yuán​zǐ hé yī gè yǎng yuán​zǐ zǔ​chéng.

   Each water molecule is composed of two hydrogen atoms and one oxygen atom.

   Source: Dong Chinese Dictionary