The periodic table is a system that scientists use to organize and classify chemical elements.

元素周期表是科学家用来记录和分类化学元素的系统r#eo&aa]2=h3SsnWj。

Originally, many scientists tried to sort the elements by properties.

最初，许多科学家试图按性质对元素进行分类m+t-!|i^%]b。

One of the early models of the periodic table arranged elements by atomic weight, which naturally grouped elements with similar properties together.

有种早期的元素周期表按原子量来排列元素，自然就将性质相似的元素放在一起了JC(Y!V(]M)。

However, certain elements were outliers, and did not fit in their groups.

然而，某些元素是“异类”，与周边元素的性质并不相似#_FbghuuDoXx6TQ[EH3。

In 1898, a scientist named J.J. Thomson discovered the electron, a subatomic particle with a negative charge.

1898年，科学家J．J．汤姆逊发现了电子，那是一种带负电荷的亚原子粒子8Fx^m9UdUK1DDGPT。

Later, in 1911, a scientist named Ernest Rutherford learned that electrons orbit a nucleus, which makes up most of the atom’s mass.

后来，在1911年，科学家欧内斯特·卢瑟福了解到，电子围绕原子核运行，而原子的大部分质量都集中在原子核上.4hn!PtAlk=#nE[@]。

Inside the nucleus, there are protons, which have a positive charge.

原子核内部有带正电荷的质子5.wiU;jeAZ#0C@dT7。

An atom has an equal number of electrons and protons.

原子有相等数量的电子和质子pAvKVqt,%k~V|^Vs4vqn。

This number became known as an element’s atomic number.

后来，这个数字被称为元素的原子序数~3t)Ec3ej|EUs5vS。

Today, elements on the periodic table are arranged by atomic number, which gives a more accurate understanding of element properties.

如今，元素周期表上的元素是按原子序数排列的，这使人们对元素的性质有了更准确的理解uCSbeO|[;1lnn^。