What is an atom

Atoms are the fundamental building blocks of the universe, composed of a nucleus with protons and neutrons, and surrounded by electrons. The nucleus is positively charged, while electrons are negatively charged, creating an attraction. Most of an atom's mass is in the nucleus, but its size is defined by the electron orbits. Electrons orbit in specific shells with distinct energy levels. The video explores these concepts and the differences in atomic structures across elements.

Explain the concept of atomic size and how it is measured.

What is the significance of electron shells in an atom?