Unraveling the Building Blocks of Matter

Atoms are the fundamental units of matter that make up everything around us. Each atom consists of three main subatomic particles: protons, neutrons, and electrons.

• Protons are positively charged particles found in the nucleus (center) of the atom.
• Neutrons have no charge and are also located in the nucleus.
• Electrons are negatively charged and orbit the nucleus in regions called electron shells.

The number of protons defines the element (for example, all hydrogen atoms have 1 proton), while neutrons can vary and create different isotopes. Electrons determine how atoms interact and bond with each other.

Atomic Number and Mass Number

The atomic number is the number of protons in an atom, and the mass number is the sum of protons and neutrons.

Models of the Atom

Early models, like the "plum pudding" model, were replaced by more accurate ones such as the Bohr model and the quantum mechanical model. The Bohr model introduced the concept of electrons orbiting the nucleus in fixed energy levels.

Real-world Connection

Understanding atoms helps us grasp why elements behave differently and how materials are created, from the air we breathe to the devices we use daily.