Week 1 BC lecture

Importance of Chemistry in Biomedical Science

• Chemistry as a Central Science:

  • Chemistry is often referred to as the central science due to its role in connecting and integrating concepts from various scientific disciplines, particularly in biology and medicine.

  • A deep understanding of chemical interactions and molecular structures is crucial for studying biological processes and developing medical technologies.

First Lecture Learning Outcomes

• Key Concepts Covered:

  • Atomic structure, electronic configurations, and the distribution of electrons in atoms.

  • Drawing and interpreting Lewis structures and resonance structures which are vital for visualizing chemical bonding.

  • Molecular geometry and understanding the polarity of molecules, which are essential for predicting chemical reactivity and interactions.

Key Definitions in Chemistry

• Chemistry: The study of the nature, properties, and transformations of matter, focusing heavily on electron interaction and the principles governing chemical reactions.

• Atoms and Matter: Atoms are the fundamental building blocks of matter, which is defined as anything that occupies space and has mass.

Atomic Structure

Subatomic Particles

• Protons (positively charged), neutrons (neutral), and electrons (negatively charged) are the three primary subatomic particles that make up an atom.

• The atomic number (Z) is defined by the number of protons in the nucleus, which also corresponds to the number of electrons in a neutral atom, determining its chemical identity.

Electron Configuration

• Electrons are distributed among energy levels and subshells (s, p, d, f), influencing the atom's chemical properties.

• Valence electrons are particularly crucial for bond formation and determining the reactivity of an atom in chemical reactions.

Chemical Bonding

Types of Chemical Bonds

• Ionic Bonds: Formed through the complete transfer of electrons from one atom to another, resulting in charged ions that attract each other due to electrostatic forces.

• Covalent Bonds: Occur when electrons are shared between atoms, with molecular geometry significantly influenced by the structure of these shared electrons.

• Weak Interactions: Include hydrogen bonds and dipole-dipole interactions, both of which are critical in dictating the biochemical properties of molecules.

Molecular Geometry and VSEPR Model

• VSEPR Theory (Valence Shell Electron Pair Repulsion Theory): Predicts the three-dimensional shape of molecules based on the repulsion between electron domains around a central atom.

• Molecular shapes can be linear, trigonal planar, tetrahedral, etc., and the presence of lone pairs on the central atom can significantly affect these geometries.

Chemical Equilibria

• Concept of Equilibrium: Refers to the dynamic balance in reversible reactions, where the concentrations of reactants and products remain constant over time.

• Equilibrium Constants (K): Expressed to convey the relationships between the concentrations of reactants and products: [ K_{eq} = \frac{[Products]}{[Reactants]} ]

• Le Châtelier's Principle: Describes how a system at equilibrium adjusts to changes in conditions (stress) to restore balance, crucial in understanding reaction dynamics.

Acids and Bases Overview

• Brønsted-Lowry Definition: States that acids donate protons (H+), while bases accept them, forming the backbone for acid-base reaction explanations, particularly in aqueous solutions.

• Strength of Acids/Bases:

  • Strong acids and bases fully dissociate in solution (e.g., hydrochloric acid (HCl), sodium hydroxide (NaOH)).

  • Weak acids and bases establish an equilibrium state (e.g., acetic acid, ammonia), which is crucial for biological pH regulation.

pH and pKa Values

• pH: The negative logarithm of the concentration of hydronium ions (H3O+) in a solution, indicating its acidity or basicity. [ pH = -\log[H_{3}O^{+}] ]

• pKa: The pH at which the concentrations of an acid and its conjugate base are equal, serving as a measure of acid strength; more potent acids have lower pKa values, highlighting their stronger tendencies to donate protons.

Buffer Solutions and Their Functionality

• Buffers: Solutions designed to maintain a stable pH upon the addition of small amounts of acids or bases; they are comprised of weak acids and their conjugate bases, functioning to resist drastic pH changes.

• Buffers are especially effective within a range near the pKa value of the weak acid they contain.

• Henderson-Hasselbalch Equation: A crucial tool for calculating the pH of buffer solutions: [ pH = pK_{a} + \log\left(\frac{[A^{-}]}{[HA]}\right) ]

Conclusion and Transition to Next Week

• A comprehensive overview of concepts learned in this lecture, emphasizing the foundational importance of chemistry within bioscience studies.

• A reminder of upcoming workshop topics and a preparatory note acknowledging the transition into more detailed exploration of biochemical aspects in the following lectures.