Atoms are the smallest units of matter that retain the properties of an element. Each atom consists of a central nucleus made up of positively charged protons and neutral neutrons, surrounded by negatively charged electrons orbiting the nucleus. The number of protons in the nucleus defines the chemical element, while electrons govern its chemical behavior. Atoms combine to form molecules, which make up all substances around us. Although atoms themselves are extremely small and cannot be seen with conventional microscopes, they are the fundamental building blocks of everything that has mass and occupies space.
