What Is an Atom?
An atom is the smallest unit of ordinary matter that forms a chemical element, serving as the building block of all physical substances. It consists of a central nucleus surrounded by a cloud of electrons. The nucleus contains protons and neutrons, while electrons orbit the nucleus in energy levels, held by electromagnetic forces.
Roles of Protons, Neutrons, and Electrons
Protons are positively charged particles in the nucleus that determine the atom's identity through its atomic number. Neutrons, neutral particles also in the nucleus, provide stability and contribute to isotopes by varying mass without changing the element. Electrons, negatively charged, occupy shells around the nucleus and balance the protons' charge, enabling chemical bonding.
How Protons, Neutrons, and Electrons Interact
Protons and electrons interact via electromagnetic attraction, keeping electrons in orbit around the nucleus. Neutrons stabilize the nucleus by countering proton repulsion through the strong nuclear force. In a neutral atom, the number of protons equals electrons, preventing net charge; imbalances create ions, as seen in sodium losing an electron to become Na+.
Importance in Chemistry and Physics
Understanding these interactions explains chemical reactions, bonding, and material properties. For instance, electron sharing forms molecules like water (H2O), while nuclear interactions power stars via fusion. This knowledge underpins technologies from batteries to medical imaging, highlighting atoms' role in everyday science.