For a long time, atoms were thought to be the smallest, most fundamental building blocks of matter. The word atom even comes from the Greek word atomos, which means "indivisible." But in the late 19th century, experiments with cathode rays, which are streams of particles in vacuum tubes, suggested there was something smaller.

In 1897, the physicist J.J. Thomson was studying these rays. He found that they were made of particles that were incredibly small, much smaller than any known atom, and carried a negative electric charge. He had discovered the first subatomic particle: the electron.

So what exactly is an electron? It's a fundamental particle, meaning it can't be broken down into smaller pieces. It's a member of a family of particles called leptons.

Electrons have a few key properties that define them.

Electrons are a crucial part of an atom's structure. They move in the space surrounding the atom's dense central core, called the nucleus. The nucleus contains positively charged protons and neutral neutrons.

The negative charge of the electrons is attracted to the positive charge of the protons. This electromagnetic force is what holds the atom together, keeping the electrons bound to the nucleus.

The number and arrangement of electrons in an atom determine its chemical properties. When atoms bond to form molecules, it's the outermost electrons that do all the work, getting shared or transferred between atoms. Without electrons, there would be no chemistry.

Because they are charged particles, electrons are affected by electric and magnetic fields. An electric field will push or pull on an electron, causing it to accelerate. A magnetic field will cause a moving electron to change its direction, forcing it into a curved path.

This behavior is the basis for much of our technology. The controlled flow of electrons through a material is what we call an electric current. It's what powers our lights, computers, and everything else that plugs into a wall.

Understanding the electron was the first step into the world of particle physics, and it opened the door to understanding everything from chemical bonds to the electricity that powers our lives. It's a small particle with a huge impact.