Atomic Structure and the Periodic Table: Properties and Trends
Limitations of the Bohr Model
The Bohr model could not explain why the orbits were quantized, nor why some properties of the elements are repeated periodically. Experimental results also did not fit this model:
- By increasing the resolution of the spectrograph, it was shown that some lines of the spectrum were in fact two.
- When making the spectrum while the substance is subjected to an intense magnetic field, it was observed that some spectral lines unfold into several.
Quantum Mechanical Model
The basic
Read MoreElectrochemistry and Cement: Principles and Applications
Electrochemistry
What is EMF, and What is its Significance in Electrochemistry?
- EMF (Electromotive Force) is the potential difference between two electrodes when no current flows. It drives the redox reaction in an electrochemical cell.
- Significance:
- Determines the spontaneity of a reaction (\(\Delta G^\circ = -nFE^\circ_{cell}\)).
- Measures the energy available for work.
- Helps calculate thermodynamic parameters like the equilibrium constant and Gibbs free energy.
Working Principle and Reactions in a Glass
Intermolecular Bonds: Types and Characteristics
Intermolecular Bonds
Intermolecular bonds are bonds between atoms that form molecules or ionic compounds.
Types of Intermolecular Bonds
- Ionic Bonds
- Covalent Bonds
- Metallic Bonds
Ionic Bonds
An ionic bond is the electrostatic attraction between two or more ions of opposite charges. The resulting structure must be electrically neutral and have a noble gas configuration. It is a bond between a metal and a non-metal, with a strong bond forming solid ionic compounds. These substances are in the form of ionic
Read MoreMatter Structure: Atoms, Bonds, and Reactions
Structure of Matter
Dalton thought that an atom could not be broken into smaller pieces.
Thomson discovered that cathode rays were negative particles, which he called electrons.
Rutherford bombarded gold foil with positively charged particles and observed that some were barely diverted, while others bounced around. His conclusions were:
- All positive charge is concentrated in the nucleus.
- The lightweight core of the hydrogen atom is formed by a positively charged particle called a proton.
- The nuclei of
Key Figures in Atomic Theory and Chemistry
John Dalton
British physicist and chemist
His studies included meteorological observations.
Origin of instruments for rain and weather measurements.
1. Large measure of weather phenomena.
What was Dalton’s first work? Observations and tests in 1773.
Key theory: Elements and compounds.
His theory consisted of the atomic nature of elements and compounds: Material formed by atoms.
Atoms of different masses combine in simple ratios to form compounds.
How did the atomic theory emerge? Through the study
Read MoreWater Treatment: Clarification, Filtration, Disinfection, and Softening
Water Clarification
Clarifiers of American origin act by carrying out two operations simultaneously on the same device, in addition to proceeding with the automatic removal of sludge. The flocculant and the raw water are introduced through the top and make contact with preformed sludge kept in suspension by a horizontal vane agitator, P, driven by a variable speed motor, M.
Water Filtration
Filtering aims to retain the particles in suspension that the water carries, both from the raw water and originating
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