atom, parts of an atom, protons, neutrons, electrons

A Quick Guide to the Atomic Structure

Read Time: 4 minutes

Atoms make up everything in the universe. That’s why it’s important for scientists to understand the atomic structure. Every being, from the biggest star to the smallest single-celled organism, owes its existence to a unique arrangement of atoms. Atoms are the smallest unit of matter that can’t be divided using any chemical method.

You can break them into their subatomic particles, but you’d better do it safely. Splitting an atom results in a massive release of nuclear energy. What makes up these particles? Let’s look at the atomic structure and the history of the atom — plus, learn about why understanding what these tiny particles are is so important.

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The History of the Atom

Humans have speculated about the universe’s origins and it’s building blocks for as long as we’ve been forming conscious thoughts. Back in the fifth century BC, two ancient Greek scientists theorized that matter was composed of indivisible building blocks they called atomos. The word atomos, in the ancient Greek tongue, translates to “indivisible.”

Scientists didn’t start actively theorizing about the atomic structure until 1661. That is when an English chemist named John Dalton published his book, “A New System of Chemical Philosophy.” Dalton is now credited with creating the first viable atomic theory, though people largely ignored his studies until the end of the 19th century.

Dalton theorized many of the things we now accept as truth, like the fact that all atoms of a single element are identical. Just like the ancient Greeks, Dalton also theorized that atoms were indestructible — at least by chemical means.

In 1934, after discovering the three different subatomic particles that make up every single atom, an Italian physicist named Enrico Fermi used an early particle accelerator to bombard atoms with neutrons, creating radioactive isotopes. Four years later, Otto Hahn and Fritz Strassmann of Germany used this same method to split the first uranium atom. They created the first instance of nuclear fission.

The rest is, as they say, history. Why did neutrons end up being the magic wand when it came to splitting the atom? To answer that question, we need to take a closer look at the three subatomic particles that make up every single atom. Understanding the parts of an atom will help you find the solution.

Positive Protons

Protons are one of the two subatomic particles that make up an atom’s nucleus. Ernest Rutherford discovered these particles during his gold foil experiments in 1911. During this experiment, he sent alpha particles — the nuclei of helium atoms — toward thin sheets of gold foil.

Positive alpha particles were deflected, while those that carried negative or no charge passed through. This experiment allowed Rutherford to theorize the existence of protons. He also discovered that these particles hold a positive charge.

Neutral Neutrons

Neutrons are the other subatomic particle, besides protons, that reside in the nucleus of every atom. Instead of possessing an opposing charge to the positive proton, neutrons don’t carry a charge at all.

There’s a popular joke in the Fallout game franchise — a neutron walks into a bar and asks the bartender how much it costs for a drink. The bartender looks him over and says, “For you, no charge.”

Pause for a laugh.

Neutrons weren’t discovered until 1932 by James Chadwick. He detected the particles by bombarding atoms with penetrating radiation. The neutral nature of these particles also explains why they were perfect for Enrico Fermi’s atom-splitting method. Neutrons have no charge, so they aren’t repelled by positively charged protons or negatively charged electrons. Therefore, they can pass unimpeded directly to an atom’s nucleus.

Negative Electrons

Electrons represent the earliest discovery when it comes to subatomic particles. Sir John Joseph Tomson discovered them in 1897 during an experiment that involved cathode rays. He figured out that the cathode rays he was using had negative charges, and that they aren’t a part of the atom’s nucleus.

Instead, electrons orbit the nucleus in shells that can only hold a certain number of particles. In 1913, Niels Bohr developed a model of the atom that included electron shells. He also synthesized the theory that for electrons to move from an inner shell to an outer one, they would need to absorb energy. Conversely, they would need to release energy to move closer to the nucleus.

The atom’s outer shell is known as the valence shell. In most cases, this is where the most reactive electrons are going to hang out. Exchanging electrons between valence shells is what creates atomic bonds.

This information is just a small sampling of the subatomic particle that makes up the universe. These three components might make up the atoms you’re familiar with, but dozens exist that are even smaller. Understanding these might help us understand the universe.

The Importance of Atomic Structure

Why is it so important for scientists to understand the parts of an atom?

In addition to constituting everything in the universe, it determines a lot of different things, such as bonding strength, magnetic properties, electrical conductivity and even melting/boiling points for various elements. Chemists can use this information to predict chemical reaction rates and in which direction a reaction will go.

Physicists use atoms to monitor the spectrum of radiation to see which elements might be safe for a given application. They can also dictate which ones would be dangerous without the proper safety equipment.

It is essentially the cornerstone of chemistry, physics and all their related branches. By understanding how these elements work at the atomic level, we can build a comprehensive picture of how they’ll react with in any given circumstance.

Using the Parts of an Atom to Study Our World

Atoms create everything around us. Understanding their structure and how they work is necessary for more than passing a middle-school science exam. This knowledge can help chemists and physicists understand how the world works at its core.

A Quick Guide to the Atomic Structure
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Article by: Megan Ray Nichols

Megan Ray Nichols is a freelance science writer and science enthusiast. Her favorite subjects include astronomy and the environment. Megan is also a regular contributor to The Naked Scientists, Thomas Insights, and Real Clear Science. When she isn't writing, Megan loves watching movies, hiking, and stargazing.