Atoms are the ultimate building blocks of the universe, composed of three fundamental particles: protons, neutrons, and electrons. They make up everything we see, touch, and experience in the world, from the smallest grain of sand to the largest galaxy. Though incredibly small and invisible to the naked eye, atoms hold the secrets to the structure and behavior of matter.
Table of Contents
Building Blocks of the Universe: Atoms
Have you ever seen a mason constructing walls, then turning those walls into a room, and eventually a collection of rooms to create a building? What is the basic unit of that large structure? What about the building block of an ant-hill? It’s a tiny grain of sand. In the same way, the basic units of all matter are atoms.
An atom is the smallest part of an element that can exist on its own or combine with other atoms, either of the same element or a different one. Every substance in the universe, whether solid, liquid, or gas, is composed of atoms. These tiny particles are made up of three main components: protons, electrons, and neutrons.
Fundamental particles of an atom
Protons: These positively charged particles reside in the nucleus (the center of the atom). The number of protons in an atom determines its atomic number and, therefore, its identity as a particular element (e.g., hydrogen has one proton, oxygen has eight protons). Protons contribute to the overall mass of the atom. The positive charge of protons attracts the negatively charged electrons, keeping them bound to the atom.
Neutrons: Neutrons are neutral particles, meaning they carry no charge. They also reside in the nucleus alongside protons. Neutrons play a key role in stabilizing the nucleus by balancing the repulsive forces between positively charged protons. Neutrons contribute to the atomic mass but not the atomic number.
Electrons: Electrons are negatively charged particles that orbit the nucleus in regions called electron shells or orbitals. These particles are much smaller than protons and neutrons and are responsible for the chemical properties of an atom including bonding and reactions. They balance the positive charge of protons, making the atom electrically neutral when the numbers are equal. Electrons in the outermost shell, called valence electrons, are especially important in chemical bonding.
Properties of the proton, electron and neutron
| Proton | Electron | Neutron | |
| Charge / C | +1.602 X 10-19 | -1.602 X 10-19 | 0 |
| Charge number (relative charge) | 1 | -1 | 0 |
| Rest mass / kg | 1.673 X 10-27 | 9.109 X 10-31 | 1.675 X 10-27 |
| Relative mass | 1837 | 1 | 1839 |
A neutron and a proton have nearly the same mass, while an electron has a much smaller, negligible mass in comparison (see Table). The charge of a proton is positive and equal in magnitude but opposite in sign to the negative charge of an electron. A neutron, on the other hand, carries no charge. In any atom, the number of protons equals the number of electrons, making the atom electrically neutral.
The nucleus of an atom, made up of protons and neutrons, carries a positive charge. Electrons occupy the space surrounding the nucleus. Almost all the atom’s mass is concentrated in the nucleus, even though the nucleus takes up only a tiny fraction of the atom’s volume. The radius of the nucleus is approximately 10-15 meters, while the atom’s size is about 105 times larger. This means the nucleus has an incredibly high density.
Conclusion
Atoms are the basic building blocks of matter, composed of three fundamental particles: protons, neutrons, and electrons. Protons and neutrons form the dense, positively charged nucleus, which contains nearly all the atom’s mass. Electrons, much lighter and negatively charged, orbit the nucleus in a vast surrounding space. Together, these particles determine the structure, properties, and behavior of all matter. Also check our other article on The Dynamic Power of Chirality And Optical Activity.
The below video also explain how the 3 important Atoms is the building blocks of the universe.
