Atomic Structure Basics

Atomic Structure

Subatomic Particles

• Protons: positively charged, found in the nucleus, atomic number (number of protons) defines the element
• Neutrons: no charge, found in the nucleus, atomic mass (protons + neutrons) defines the isotope
• Electrons: negatively charged, orbit the nucleus, equal in number to protons (neutral atom)

Atomic Nucleus

• Nucleus: central region of the atom, composed of protons and neutrons
• Atomic Number: number of protons in the nucleus, defines the element (e.g., H=1, C=6, O=8)
• Atomic Mass: total number of protons and neutrons in the nucleus, defines the isotope (e.g., carbon-12, oxygen-16)

Electron Configuration

• Energy Levels (Shells): electrons occupy specific energy levels around the nucleus
• Electron Cloud: region where electrons are likely to be found
• Valence Electrons: outermost energy level, participate in chemical bonding

Atomic Size and Shape

• Atomic Radius: distance from the nucleus to the outermost energy level
• Electron Cloud Shape: influenced by the number of electrons and energy levels

Key Concepts

• Atomicity: atoms are the building blocks of matter
• Element: a substance consisting of atoms with the same atomic number
• Isotope: atoms of the same element with different atomic masses