Atomic structure revision notes

Understanding Atomic Structure

Atomic structure is foundational to chemistry, evolving through historical scientific discoveries. An atom consists of a nucleus made up of protons and neutrons, surrounded by electrons in defined energy levels. The relative charges are +1 for protons, 0 for neutrons, and -1 for electrons, with respective masses of approximately 1 amu for protons and neutrons and negligible mass for electrons.

Key Concepts:

• Atoms, Ions, and Isotopes: Atoms are neutral, ions are charged particles, and isotopes are variants of elements with differing neutron counts.
• Mass Number and Atomic Number: The mass number is the total number of protons and neutrons, while the atomic number is the number of protons. This helps determine the number of electrons in neutral atoms and ions.
• Isotopes: Isotopes exist due to variations in neutron numbers, affecting atomic mass but not chemical properties.
• Mass Spectrometry: A technique used to identify isotopes and calculate relative atomic masses based on isotopic abundance.
• Electron Configuration: Electrons are arranged in shells and subshells (s, p, d) up to atomic number 36, influencing chemical behavior.
• Ionisation Energy: The energy required to remove an electron from an atom. Trends in ionisation energy provide insights into atomic structure, including the presence of shells and subshells.