Chemical Bonding & Periodic Table Essentials
Molecular Union & Crystal Structure
Molecular union of atoms results in discrete groups. Network crystals have millions of atoms ordered regularly. Chemical linkage is the force of attraction holding atoms in a molecule or crystal, known as chemical bonds.
Octet Rule
Atoms of different chemical elements tend to unite to achieve stability by having eight electrons in their last layer, called the octet.
Ions
Cation: Metallic element losing electrons, positively charged.
Anion: Non-metallic element gaining
Nuclear Reactors and Radioactivity Essentials
Nuclear Reactor Basics
A nuclear reactor is an installation where nuclear reactions occur. Key components include:
- Fuel Rods: Mixed uranium-containing aluminum, allowing fluid circulation.
- Reactor Core: Contains fuel rods, typically cooled with H2O.
- Control Rods: System to start or stop nuclear fission chain reactions.
- Moderator: Ensures continuity in the chain reaction by managing neutron speeds.
- Refrigerant: Removes fission heat by plunging into the nucleus.
- Shield: Biological shield preventing radiation
Evolution of Atomic Models: From Democritus to Quantum Mechanics
First Atomic Models
Democritus (450 BC)
Proposed the idea of atoms as indivisible particles.
Dalton Atomic Model
Introduced atomic-molecular theory:
- Matter consists of indivisible atoms.
- Atoms of the same element have identical mass and properties.
- Compounds form from combinations of different elements.
- Mass is conserved in chemical reactions.
- Law of multiple proportions.
Lavoisier: Law of Conservation of Mass
Proust: Law of Definite Proportions
Atomic Model – Thomson
Discovered electrons through cathode ray
Read MoreIndustrial Processes: Filtration, Drying, Mixing, and More
Liquid Mixing vs. Solid Mixing
Liquid Mixing
- Generally involves liquid-liquid or liquid-gas mixing.
- Depends on flow currents for material transport.
- Requires less power.
- Results in a homogenous liquid phase.
- Well-mixed samples are homogenous.
- Equipment: Liquid agitators.
- Technology is well-understood and simple.
Solid Mixing
- Resembles low-viscosity liquid mixing to some extent.
- Lacks flow currents in heavy masses; mixing occurs differently.
- Requires higher power.
- Product may have identifiable phases.
- Well-mixed
Atomic Structure: From Dalton to Quantum Theory
Structure of the Atom
In 1808, English chemist J. Dalton formulated his atomic theory, postulating that matter consists of indivisible atoms. This concept prevailed until the discovery of natural radioactivity by Henri A. Becquerel in 1896, revealing alpha, beta, and gamma rays, suggesting atoms were divisible.
The Electron: Plum Pudding Model
Studies on gas conductivity at low pressure revealed cathode rays, streams of negatively charged particles. J.J. Thomson identified these as electrons. In 1911,
Read MoreUnderstanding Chemical Bonds and Hydrocarbons
Chemical Bonding
Chemical bonding is the joining of atoms, molecules, or ions to create larger structures. These molecules can further interact through intermolecular forces to form more complex, multimolecular structures.
Types of Chemical Bonds
- Ionic Bond: Occurs due to electrical forces between oppositely charged ions, forming an ionic crystal.
- Covalent Bond: Forms when atoms share a pair of electrons, typically completing their valence shells.
- Metallic Bond: Results from the electrical attraction