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Electrodes: Definition & Types

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  • 0:01 Definition & Background
  • 1:47 Anodes & Cathodes
  • 2:31 How Does an Electrode Work?
  • 4:37 Lesson Summary
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Lesson Transcript
Instructor: Danielle Reid

Danielle has taught middle school science and has a doctorate degree in Environmental Health

An electrode is a pretty versatile material - you can find one in your non-rechargeable battery or an electrolytic cell. Continue reading to learn about the two types of electrodes - anodes and cathodes - and how they function in electrical devices.

Definition and Background

Before you read this lesson, grab a non-rechargeable battery. If you don't have one, don't panic, you can just follow along using this image.

As you look at the battery, you will notice it has two ends. That is, there is a positive sign on one end and a negative sign on the other end. Did you know these signs are representative of two different types of electrodes, an anode, and cathode? Before we continue dissecting our battery, let's discuss more about this term 'electrode' in more detail.

Illustration of a Non-Rechargeable Battery
battery

Electrode refers to a conductor by which electrical currents can travel. In fact, these little guys are sometimes referred to as electrical conductors. You can find them in a wide variety of electrical devices such as batteries, electrolytic cells, or electron tubes.

You might be wondering what is an electrode made of. Well, what do you suspect is a great conductor of electricity? Metals are great conductors of electricity. In fact, metals are commonly used in the production of electrodes. The type of metals used range from copper to zinc to gold and platinum.

Think of an electrode as a bridge that forges a passageway for electrons to travel on. Electrons are the guys zipping around the nucleus of an atom. Technically, they're subatomic particles with a negative electric charge.

Atoms have protons too, which have a positive charge. Atoms with the same number of protons and electrons are called neutral, because their charges cancel each other out.

However, if the number of electrons are different from the proton count, the atom will either be negative or positive. We can call that atom an ion. There are two different types of ions:

  1. Cations are positively charged ions.
  2. Anions are negatively charged ions.

Anodes and Cathodes

Similarly, there are two different types of electrodes:

  1. An anode is an electrode that attracts anions.
  2. A cathode is an electrode that attracts cations.

A helpful way to remember the relationship between ions and electrodes is to know that 'cat' in cathode refers to cation. The first letter 'a' in anode refers to anion.

When you connect both electrodes together, you can form an electrical circuit. An electrical circuit is the path by which electrons flow. Thus, if the electrode is our bridge that electrons travel on, the circuit is the road map electrons use to determine where to travel. In electrical devices, electrons will always flow from the anode to the cathode.

How Does an Electrode Work?

In describing how an electrode works, there are two different electrical devices we can use as examples. The first example involves our battery. As shown in this diagram, a battery has two terminal ends, the cathode and anode. Two different processes occurring inside the battery contribute to the flow of electrical current. First, chemical reactions are firing off within the battery. Second, we have electrons zooming around from the anode and cathode to generate electricity for a device.

Function of an Electrode in a Battery
battery

Let's say you'd like to power a flashlight. When you place the battery in its holder, chemical reactions take place. These reactions release a lot of ions at the anode. As the ions dissolve they leave their electrons behind at the anode.

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