Atomic Structure Fundamentals

Atomic Structure

Basic Components

• Proton: positively charged, found in the nucleus, mass = 1 amu (atomic mass unit)
• Neutron: no charge, found in the nucleus, mass = 1 amu
• Electron: negatively charged, found in the electron cloud, mass = 1/1836 amu

Atomic Nucleus

• Nucleus: central region of the atom, made up of protons and neutrons
• Atomic Number (Z): number of protons in the nucleus, defines the element
• Mass Number (A): total number of protons and neutrons in the nucleus, represents the atomic mass

Electron Cloud

• Electron Cloud: region around the nucleus where electrons are found
• Energy Levels: electrons occupy specific energy levels or shells around the nucleus
• Valence Shell: outermost energy level, involved in chemical bonding

Electron Configuration

• Electron Configuration: arrangement of electrons in an atom's energy levels
• Aufbau Principle: electrons occupy the lowest available energy level
• Pauli's Exclusion Principle: no two electrons in an atom can have the same set of quantum numbers

Atomic Radius and Atomic Size

• Atomic Radius: distance from the nucleus to the outermost electron
• Atomic Size: varies depending on the element, generally increases down a group and decreases across a period