Introduction to Chemistry: Core Concepts for Medical Admissions

Chemistry for Medical Admissions

Introduction

This section provides an overview of the essential chemistry topics required for entry into medical studies. The content aligns with foundational concepts in introductory college chemistry, focusing on both general and organic chemistry relevant to biological and medical contexts.

1. Fundamentals of Chemistry

1.1 Atomic Structure

• Proton, Neutron, Electron: Subatomic particles that make up atoms. Protons (+) and neutrons (neutral) are found in the nucleus, while electrons (-) orbit the nucleus.

• Atomic Number (Z): Number of protons in an atom; defines the element.

• Mass Number (A): Sum of protons and neutrons in the nucleus.

• Isotopes: Atoms of the same element with different numbers of neutrons.

1.2 Chemical Properties and Bonding

• Electronegativity: The tendency of an atom to attract electrons in a bond.

• Periodic Trends: Electronegativity, atomic radius, and ionization energy vary across the periodic table.

• Covalent and Ionic Bonds: Covalent bonds involve sharing electrons; ionic bonds involve transfer of electrons.

1.3 Solutions and Concentrations

• Solubility: The ability of a substance to dissolve in a solvent.

• Concentration Units: Molarity (M) is moles of solute per liter of solution.

• Example: To prepare 0.9% saline, dissolve 9 g NaCl in 1 L water.

1.4 Moles and Calculations

• Mole: The amount of substance containing $6.022 \times 10^{23}$ particles (Avogadro's number).

• Molar Mass: The mass of one mole of a substance (g/mol).

• Equation: $\text{Moles} = \frac{\text{Mass (g)}}{\text{Molar Mass (g/mol)}}$

2. Fundamentals of Acids, Bases, and pH

2.1 Definitions

• Acid: Substance that donates protons ($H^+$) in solution.

• Base: Substance that accepts protons or donates hydroxide ions ($OH^-$).

• pH Scale: Measures acidity/alkalinity; $\text{pH} = -\log_{10}[H^+]$

2.2 Calculations and Buffers

• pH Calculation: For a solution with $[H^+] = 1 \times 10^{-7}$ M, $\text{pH} = 7$.

• Buffers: Solutions that resist changes in pH when acids or bases are added.

3. Nomenclature and Structure Drawing

3.1 IUPAC Nomenclature

• Alkanes, Alkenes, Alkynes: Saturated and unsaturated hydrocarbons named according to chain length and functional groups.

• Functional Groups: Specific groups of atoms (e.g., -OH, -COOH) that determine chemical properties.

3.2 Drawing Structures

• Condensed, Expanded, and Skeletal Formulas: Different ways to represent molecules.

• Example: Ethanol can be written as CH3CH2OH (condensed) or as a structural diagram.

4. Isomerism

4.1 Types of Isomers

• Structural Isomers: Same molecular formula, different connectivity.

• Stereoisomers: Same connectivity, different spatial arrangement (e.g., cis/trans, enantiomers).

5. Alcohols, Aldehydes, Ketones, and Carboxylic Acids

5.1 Functional Groups and Properties

• Alcohols: Contain -OH group; classified as primary, secondary, or tertiary.

• Aldehydes and Ketones: Contain carbonyl group (C=O); aldehydes at end of chain, ketones within chain.

• Carboxylic Acids: Contain -COOH group; acidic properties.

5.2 Reactions

• Oxidation: Alcohols can be oxidized to aldehydes/ketones, then to carboxylic acids.

• Reduction: Reverse process; carboxylic acids to aldehydes/ketones to alcohols.

6. Amines

6.1 Classification and Properties

• Amines: Organic compounds derived from ammonia (NH3), classified as primary, secondary, or tertiary based on number of alkyl groups attached to nitrogen.

• Basicity: Amines act as bases due to lone pair on nitrogen.

7. Aromatic Chemistry

7.1 Structure and Reactions

• Aromatic Compounds: Contain benzene ring; exhibit resonance stabilization.

• Electrophilic Substitution: Main reaction type for aromatic compounds (e.g., nitration, halogenation).

• Example: Benzene reacts with nitric acid to form nitrobenzene.

Additional info:

• This summary is based on the chemistry section of a medical admissions test guide, which covers foundational topics in general and organic chemistry relevant to introductory college-level courses.

• Students are expected to be familiar with SI prefixes (e.g., kilo-, milli-, micro-, nano-).