Atomic Models: From Thomson to Quantum Theory
Atomic Models: A Historical Perspective
Thomson’s Atomic Model
Thomson’s atomic model proposed that an atom is a uniform sphere of positive electricity with electrons dispersed throughout, held apart by repulsive forces. This model attempted to explain the neutrality of atoms and the ionization process when electrons are lost.
Rutherford’s Discovery of the Atomic Nucleus
Thomson’s model failed to explain the alpha particle scattering experiments conducted by Geiger and Marsden under Rutherford’s direction.
Read MoreAtomic Properties and Periodic Trends
Atomic Properties
Electron Configuration
The electron configuration of an atom describes the distribution of its electrons among the various atomic orbitals. Several principles govern this distribution:
- Pauli Exclusion Principle: No two electrons in the same atom can have the same four quantum numbers. Each orbital can hold a maximum of two electrons with opposite spins (anti-spin).
- Building-Up Principle (Aufbau Principle): Electrons fill orbitals successively in order of increasing energy.
- Hund’s
Fundamental Chemical Laws and Concepts
The Law of Conservation of Mass
The law of conservation of mass, also known as the law of conservation of matter or the Lomonosov-Lavoisier law, states that in an ordinary chemical reaction, the mass remains constant. That is, the mass of the reactants consumed is equal to the mass of the products obtained.
Dalton’s Law (Law of Multiple Proportions)
Dalton’s law, or the law of multiple proportions, formulated in 1803 by John Dalton, is one of the most fundamental stoichiometric laws. It was demonstrated
Read MoreUnderstanding Nuclear Power: Reactions, Radiation, and Environmental Impact
Nuclear Power: An Overview
Nuclear power involves changes that occur in the nuclei of atoms during nuclear reactions. The structure of the atom consists of a nucleus containing protons and neutrons, with electrons orbiting around it. An atom is characterized by the number of protons in its nucleus. This number is called the atomic number (Z). The atomic mass (A) is the total number of protons and neutrons in an atom. Isotopes are atoms that have the same atomic number but different mass numbers.
Radioactivity
Natural
Read MoreUnderstanding Water Hardness: Causes and Properties
Hard Water: Definition and Causes
In chemistry, water hardness refers to the concentration of minerals dissolved in water, particularly calcium and magnesium salts. These minerals are the primary cause of water hardness, and the hardness level is directly proportional to their concentration. For example, rainwater becomes hard water when an increased concentration of H+ ions leads to more CO2, increasing the water’s acidity. When hard water is heated, calcium carbonate deposits form, reducing the
Read MoreMetallurgy and Pulp Production
Metallurgy
Mineral Concentration/Preparation
- Flotation: Enriches ore by removing worthless mineral species.
- Amalgamation: Creates an alloy of mercury with other metal(s).
- Magnetic Concentration: Uses electromagnets to attract magnetic minerals, separating them from non-magnetic materials.
Pretreatments
- Roasting: Converts sulfides into oxides by heating in air.
- Calcination: Converts carbonates or hydroxides into more easily reducible compounds.
Reduction
- Chemical Reduction: Employs a more electropositive