Introduction to Atoms

Atoms are the fundamental building blocks of matter. Each atom is made up of a nucleus, containing protons and neutrons, surrounded by electrons orbiting in shells.

Subatomic Particles

• Protons have a positive charge and determine the atomic number.
• Neutrons have no charge and, together with protons, make up the atomic mass.
• Electrons are negatively charged and occupy energy levels around the nucleus.

Electron Configuration

Electrons fill energy levels in a specific order: first the lowest level (closest to the nucleus), then higher ones. The arrangement of electrons determines an element's chemical properties.

Real-World Connection

Understanding atomic structure explains why elements react differently and is the foundation for studying chemical reactions.

Key Points

• Atomic number = number of protons
• Mass number = protons + neutrons
• Electrons define chemical behavior

Visualizing Atoms

Imagine the nucleus as a tiny marble in a stadium; the electrons buzz around far from the nucleus!