A-level Biology

Welcome to this A-level biology series where we break down complex topics into simple, understandable concepts. This introductory video focuses on the fundamental chemical principles behind biology, starting with the atom. We will explore atomic structure, atomic number, isotopes, and atomic weight, providing a helpful refresher for those familiar with the concepts and a clear overview for newcomers. Understanding these basics is crucial for grasping future biological topics. Elements are composed of a single type of atom, which in turn is made up of three subatomic particles: protons, neutrons, and electrons. Protons carry a positive charge and have a mass of one atomic mass unit. Neutrons have no charge but also a mass of one atomic mass unit. Electrons orbit the nucleus, have a negative charge, and their mass is negligible compared to protons and neutrons. The atomic number, defined by the number of protons, dictates the element. Atomic weight, however, accounts for isotopes, which are atoms of the same element with different numbers of neutrons, by using an abundance-weighted average of their masses. Subscribe to @AxiomTutoringCourses for more educational content.

This video explains covalent bonds by diving into the energy levels and electron configurations of atoms. We explore how elements are arranged on the periodic table based on atom size and electron energy levels, including the concept of electron shells and subshells. Learn about the S, P, D, and F blocks, and the specific rules like the Pauli exclusion principle and Hund's rule that govern electron behavior. We then use carbon as an example to determine its valence electrons and how it forms covalent bonds by sharing electrons to achieve stability. Subscribe to @AxiomTutoringCourses for more educational content.