Chemical Bonding: An In-Depth Exploration of Ionic, Covalent, and Metallic Bonds
The Periodic Table and Element Classification
The arrangement of elements in the periodic table is based on their atomic number, a concept discovered by Henry Moseley through his study of X-ray spectra. This organization reflects the electronic configuration of each element, with periods representing the filling of electron energy levels. The first period holds two elements, the second and third contain eight each. While subsequent periods also fill ‘d’ and ‘f’ sublevels, these are energetically
Read MoreChemical Equilibrium and Le Chatelier’s Principle
Chemical Equilibrium
The chemical equilibrium is a reversible process where the rates of the forward and reverse reactions are equal, resulting in constant reactant and product concentrations over time. When all species are in the same phase, the equilibrium is homogeneous.
Homogeneous Equilibria: Law of Mass Action
In a homogeneous equilibrium, all chemical species are in the same phase. A general homogeneous equilibrium is represented as: aA + bB ⇌ cC + dD. At a given temperature, a constant ratio
Read MoreFundamental Chemistry Laws, Atomic Models, and Periodic Properties
Fundamental Chemical Laws
Law of Conservation of Mass
In any chemical reaction that takes place in a closed system, mass is conserved: The mass of starting substances (reactants) is the same as that of the final products.
Law of Definite Proportions
When two or more elements combine to yield a compound, they do so in a fixed proportion.
Law of Multiple Proportions
When two or more elements combine to form different compounds, they do so in a ratio of small whole numbers.
Dalton’s Atomic Theory
- Chemical
Electron Configuration and Chemical Periodicity
Electron Configuration
Pauli Exclusion Principle
Two electrons in the same atom cannot have identical quantum numbers. Since electrons in the same orbital are identical, an orbital cannot contain more than two electrons.
The maximum number of electrons per energy level is 2n2
Electronic Configuration of the Elements
Spectral Notation
Spectral notation schematically represents the distribution of electrons in an atom based on Bohr’s atomic model. Electrons tend to occupy the lowest energy orbitals.
The
Read MoreIntroduction to Organic Chemistry: Reactions, Hydrocarbons, and Petrochemicals
Enthalpy of a Reaction
Enthalpy Change
When a process takes place at constant pressure, the heat of reaction is called enthalpy change (ΔH). Under standard conditions (1 atm pressure and 25°C), it is written as ΔH°. Enthalpy is a relative measure of the energy of the initial or final state of a system. Therefore, it quantifies the change in enthalpy.
Enthalpy of Formation
The enthalpy of formation (ΔH0f) is the heat absorbed or released when one mole of a compound is formed from its constituent
Read MoreChemical Reactions: Definition, Equation, and Factors Affecting Reaction Rate
Chemical Reaction
A chemical reaction, or chemical change, is a process in which two or more substances (called reactants) transform into other substances called products due to an energy factor.
Chemical Equation
A chemical equation is the symbolic representation of a chemical reaction.
Classification of Chemical Reactions
By How They Perform:
- Synthesis: Elements react to form a compound.
- Decomposition: A compound breaks down into two or more simpler substances.
- Replacement: An element reacts with a compound,