What is an atom? An introduction to the smallest building blocks of the universe.
The building blocks of everything around us
Have you ever wondered what everything around us is made of—from the air we breathe to the chair we sit on, and even ourselves? The answer lies in the incredibly small and invisible world of atoms. Atoms are the fundamental building blocks of all matter in the universe. In this article, we aim to answer the question “What is an atom?” in simple terms and get to know its fascinating components.
What is an atom? A simple definition
The word **“atom”** comes from the Greek word “atomos,” which means “indivisible” or “uncuttable.” Although we now know that atoms are made of even smaller particles, an atom is still the smallest unit of a chemical element that retains the properties of that element. In other words, if you keep dividing a piece of gold until it no longer has the properties of gold, you will reach gold atoms.
Atomic Structure: The Nucleus and Electrons
Atoms have a structure somewhat like a miniature solar system, although there are important differences. Each atom consists of two main parts:
- Nucleus: The nucleus is located at the center of the atom. It is extremely small but very dense and heavy compared to the rest of the atom. The nucleus has a positive electric charge.
- Electrons: Electrons are extremely light particles with a negative electric charge that move in the space surrounding the nucleus.
Components of the Nucleus: Protons and Neutrons
The atomic nucleus itself is made up of two types of particles:
- Protons: Protons are particles with a positive electric charge. The number of protons in the nucleus determines the identity of a chemical element. This number is called the atomic number and is represented by the letter Z. Each chemical element (such as hydrogen, oxygen, or iron) has a unique atomic number.
- Neutrons: Neutrons are particles without electric charge (neutral). Neutrons, together with protons, are located in the nucleus and contribute to its stability. The number of neutrons in the atoms of an element can vary; such atoms are called isotopes.
Electrons and Electron Shells
The positively charged nucleus attracts and holds the negatively charged electrons around itself through electrostatic (electric) force. These electrons move in specific energy levels or “orbits” around the nucleus. In a neutral atom, the number of electrons is equal to the number of protons; in this way, the positive and negative charges balance each other, and the atom as a whole has no electric charge. If an atom loses or gains one or more electrons, it becomes a charged particle called an ion.
Mass number: the sum of protons and neutrons
The total number of protons and neutrons in the nucleus is represented by the letter A. The mass number shows almost all of the atom’s mass, as the mass of electrons is negligible compared to protons and neutrons.
Why are atoms important?
Atoms are the fundamental building blocks of all visible matter in the universe. By combining with each other, they form molecules (such as water molecules). Molecules, in turn, create various substances with different properties. Understanding the structure and behavior of atoms is essential for studying chemistry, physics, and many other sciences.
How small are atoms?
The diameter of a typical atom is about one ten-billionth of a meter! This means that tens of millions of atoms can be lined up side by side in just one millimeter. For this reason, seeing atoms is impossible even with the most powerful ordinary optical microscopes, and advanced electron microscopes are needed to observe them.
Conclusion
In this article, we learned what an atom is and how these extremely small particles form the building blocks of our vast world. Atoms, with a nucleus made up of protons and neutrons at the center and electrons orbiting around it, present a remarkable structure that determines the properties of chemical elements. Understanding the world of atoms opens a window to a deeper comprehension of the physical universe around us. For more information, please refer to the page “What is Electricity.”