Atomic Structure, Bonding, and Properties of Matter
1. The Nuclear Model of the Atom
Democritus proposed the concept of atoms. J. Dalton’s atomic theory stated that atoms were indivisible and unchanged by chemical processes.
1.1 The Gold Foil Experiment
E. Rutherford bombarded a thin gold foil with alpha rays. He expected all particles to pass through uniformly. However, some particles were deflected, demonstrating that:
- The atom has a central core (nucleus) containing most of its mass, including protons.
- Electrons revolve in concentric circular orbits
Matter Transformation and Atomic Structure
Matter Transformation
Physical Process: A transformation where matter retains its composition, structure, and properties. For example, changes in state (solid, liquid, gas).
Chemical Process: A transformation where matter changes its composition, structure, and properties. The resulting substances are different from the initial ones. For example, burning wood.
Mixtures
A mixture is the combination of several pure substances that retain their original properties.
Heterogeneous Mixture: Does not have
Read MoreNatural Resources, Manufacturing & Environmental Management
Item 11: Natural Resources and Manufacturing
Natural Resources
Water, air, minerals, rocks, oil, natural gas, timber, and agricultural products are examples of natural resources.
Manufacturing
Key processes involve acids and bases under specific conditions (durable, accessible, abundant).
Classification of Resources
Resources are classified based on their durability:
- Inexhaustible: Air (separation of components by distillation, nitrate combination, electrical discharges, ozone), Water (desalination, potable
Alkali, Alkaline Earth, Earthy & Carbonoide Elements
Alkali Metals
The alkali metals, Lithium, Sodium, Potassium, Rubidium, Cesium, and Francium, are in Group 1 of the periodic table. They are named for the alkalinity of their compounds. Due to their chemical activity, they are not found in a free state and comprise almost 5% of the Earth’s crust (especially Sodium and Potassium).
Properties
- Electronic configuration: ns1
- Low first ionization energy
- Low electronegativity, decreasing down the group
- Common oxidation state: +1
- Form ionic compounds
- Low melting
Chemical Reactions, Equilibria, and Industrial Processes
Hess’s Law
If a reaction can be performed in several steps, whether real or theoretical, the total enthalpy change is equal to the sum of the enthalpy changes of these intermediate reactions.
Standard Enthalpy of Reaction
From standard enthalpies of formation.
From bond enthalpies.
Standard Entropy of Reaction
Free Energy
Spontaneous
Theories of Chemical Reactions
Collision Theory
For a chemical reaction to occur, reactants (atoms, molecules, or ions) must collide. Effective collisions require:
- Sufficient
Atomic Structure and Chemical Reactions
Atomic Structure
Dalton’s Atomic Theory and Its Demise
Dalton’s atomic theory proposed that matter consists of indivisible particles called atoms. However, the discovery of the electron, a subatomic particle, challenged this theory.
Cathode Rays and the Electron
Cathode rays exhibit specific properties:
- They travel in a straight line from the cathode to the anode, producing fluorescence upon hitting the tube walls.
- They behave like a negatively charged electric current, deflecting towards the positive