质子Proton

同一元素的所有原子质子数相同，中子数可以不同（同位素）。中性原子中质子数等于电子数。1913 年莫塞莱发现元素 X 射线谱线的频率与原子序数有简单关系，证明原子序数就是核电荷数，周期表应按原子序数而不是原子量排列。

All atoms of an element have the same number of protons, though their neutron numbers may differ (isotopes). In a neutral atom the number of protons equals the number of electrons. In 1913 Moseley found a simple relation between the frequencies of elements' X-ray lines and atomic number, showing atomic number is the nuclear charge and that the periodic table should follow atomic number rather than atomic mass.

氢原子失去电子后只剩一个质子，所以 H⁺ 常称为质子。布朗斯特–劳里酸碱理论把酸定义为质子给体、碱定义为质子受体。水溶液中 H⁺ 实际与水分子结合为 H₃O⁺（水合氢离子）。¹H 核磁共振谱研究的也是分子中氢原子核（质子）所处的化学环境。

A hydrogen atom that loses its electron is just a proton, so H⁺ is often called a proton. In Brønsted–Lowry theory an acid is a proton donor and a base a proton acceptor. In water H⁺ is actually bound to a water molecule as H₃O⁺, the oxonium ion. ¹H NMR spectroscopy studies the chemical environments of hydrogen nuclei (protons) in molecules.

1917–1919 年，卢瑟福用 α 粒子轰击氮气，发现产生了氢原子核，说明氢核是其他原子核的组成部分。1920 年他将其命名为 proton，源自希腊语“第一”。质子由两个上夸克和一个下夸克构成。

In 1917–1919 Rutherford bombarded nitrogen with alpha particles and detected hydrogen nuclei, showing the hydrogen nucleus is a building block of other nuclei. In 1920 he named it the proton, from the Greek for first. The proton is made of two up quarks and one down quark.