Inorganic Chemistry Seminar 1

General Chemistry Overview

• Chemistry studies matter and the changes it undergoes.
• Major branches of chemistry include Organic, Inorganic, Biochemistry, Analytical, and Physical Chemistry.

Thermodynamics

• Heat flows from hot to cold, not the reverse, unless energy is added to the system.
• All processes stop as temperature approaches absolute zero.
• A perfect crystal has zero entropy at absolute zero.

Key Concepts

• Zeroth Law of Thermodynamics: If two bodies are in equilibrium with a third, they are also in equilibrium with each other.
• Matter: Anything that occupies space and has mass; can have a definite composition and structure.

Thermodynamic Laws

• Law of Conservation of Energy: Total energy in an isolated system remains constant; energy cannot be created or destroyed.
• Internal energy increases by transferring energy to the system or through work done by surroundings.

Energy Transfer

• Surroundings performing work or transferring energy increases internal energy and is measured in joules.
• Energy change in the system is positive when internal energy increases.

Definitions

• Pure Substance: Matter with a consistent and unchanging composition; can be elements or compounds.
• Element: Simplest form of matter, cannot be decomposed by simple chemical reactions.
• Compound: A substance formed when two or more elements chemically combine in definite proportions.
• Mixture: Combination of two or more substances that retain their own properties; can be homogeneous or heterogeneous.

Entropy

• Entropy measures a system’s thermal energy dispersal per unit temperature.
• Natural spontaneous processes generally lead to an increase in total entropy.

Bohr Model and Atomic Structure

• Bohr Model, also known as the Planetary Model, presents protons in the nucleus with electrons orbiting in fixed circular paths.
• Isobars: atoms of different elements having the same atomic mass.
• Isotones: atoms of different elements that share the same number of neutrons.

Historical Development of Atomic Theory

• Democritus introduced "atomos" to describe indivisible particles, considered 90% correct.
• John Dalton proposed atomic theory, presenting atoms as solid spheres and introducing laws of definite proportion and multiple proportions.
• Rutherford-Bohr Model: describes electrons in elliptical orbits around the nucleus.

Quantum and Orbital Theories

• Orbital Theory indicates that the number of orbital types in a given shell equals the shell number, providing a 3D probability space for electron location.
• Hund’s Rule of Maximum Multiplicity: electrons occupy orbitals of the same energy level singly before pairing.
• Heisenberg Uncertainty Principle states that it is impossible to precisely measure both the position and momentum of an electron simultaneously.
• Schrödinger’s Quantum Model suggests electrons exist in probability clouds rather than fixed orbits, leading to the concept of sub-energy levels.

Periodic Trends

• Atomic Radius: Distance between two nuclei, increases down a group.
• Electronegativity: Tendency of an atom to attract electrons, increases across a period.
• Ionization Potential: Energy required to remove an electron from an atom, reveals increasing trends.

Atomic Composition

• Atoms consist of a positively charged nucleus (protons and neutrons) with an equal number of electrons to balance the positive charge.
• Protons (positively charged) established by Rutherford’s Gold Foil Experiment; electrons (negatively charged) demonstrated by the Cathode Ray Tube experiment by Karl Ferdinand Braun.
• Neutrons (neutral particles) discovered by James Chadwick, contributing to atomic mass.

Molecules and Compounds

• Molecules are the smallest units of a pure substance with distinct chemical properties.
• Inorganic compounds can be classified into acids (which contain replaceable hydrogen), bases, and salts.
• Examples of metallic compounds include calcium carbonate and aluminum sulfide.

Hydrocarbons

• Alkenes have double bonds between carbon atoms, represented by the formula CnH2n and classified as sp2 hybridized with IUPAC naming ending in -ene.

Alcohol Classification

• Monohydric: containing one -OH group.
• Dihydric: containing two -OH groups.
• Polyhydric: containing multiple -OH groups.

Ethers and Carbonyl Compounds

• Ethers consist of an oxygen atom bonded to two alkyl or aryl groups, with cyclic ethers (like ethylene oxide) forming a ring structure.
• Carbonyl compounds include functional groups characterized by the presence of a carbon atom double-bonded to an oxygen atom.

Key Principles in Quantum Chemistry

• Pauli’s Exclusion Principle: no two electrons in the same atom can have identical quantum numbers, maintaining unique electron states.
• Aufbau Principle: electrons fill the lowest energy orbitals first before occupying higher ones.