Atomic Structure and Quantum Theory Fundamentals
Z (Atomic Number) = Number of Protons = Number of Electrons.
A (Mass Number) = Protons + Neutrons.
Origins of Quantum Theory
Although the Rutherford model successfully explained the observed experimental evidence, it was inherently inconsistent. It was known that when an electric charge (q) moves with accelerated motion, it loses energy in the form of electromagnetic radiation. The electron in circular motion around the nucleus is subjected to centripetal acceleration; therefore, it must lose energy.
Read MoreChemical Reactions and Laws: Essential Concepts
Chemical Reactions and Fundamental Laws
Chemical Reaction: A process involving the combination of two or more initial substances, called reagents, resulting in new products. These products possess physical and chemical properties entirely distinct from the starting substances.
Key Laws Governing Chemical Reactions
Lavoisier’s Law (Law of Conservation of Mass): In any chemical reaction, the total mass of the reactants is equal to the total mass of the products. In essence, “In a chemical reaction,
Read MoreThermochemistry and Chemical Equilibrium
Work and Heat
Reversible processes are those in which the system and surroundings are in constant equilibrium; involves infinitesimal changes to some property:
- Slow heating
- Slow expansion
Irreversible processes are those in which the system and surroundings are not in equilibrium:
- Expansion against constant pressure
- Phase change at non-standard transition temperature
Internal Energy
For isothermal processes where ΔT = 0, ΔU = 0 and therefore q = -w.
At constant volume, ΔU = q.
Enthalpy
At constant pressure,
Read MoreChemical Processes in the Environment
Environmental Chemistry
Atmospheric Chemistry (Acid Rain, Smog)
In the air, there are a variety of chemicals. Often, these chemicals combine with each other through chemical reactions, creating new types of chemicals. This is called “atmospheric chemistry.” Earth’s atmosphere has different layers. The lowest layer is called the troposphere. We live in the troposphere. Some of the chemicals in the air come from pollution. Most of the gas in our atmosphere is nitrogen. Approximately 4/5 of air is nitrogen.
Read MoreUnderstanding Matter: Properties, Changes, and Laws
Physical Property
A characteristic of matter that can be observed or measured without changing the sample’s composition; also describes a pure substance having a uniform and unchanging composition.
Extensive Property
Physical properties that are dependent on the amount of a substance present, such as length, shape, weight, and volume.
Intensive Properties
Physical properties of matter that are independent of the amount of a substance, such as density, color, and specific heat.
Chemical Properties
The ability
Understanding the Periodic Table of Elements
ITEM 8 – Periodic Table
- Pure Substance: A substance that consists of a single component, has characteristic properties and a fixed, unchanging chemical composition. It cannot be separated into other components by physical methods.
- Mixture: A combination of two or more substances in a way that does *not* produce a chemical reaction. The individual components maintain their identity and chemical properties.
- Chemical Element: Pure substances that cannot be decomposed into any other simpler pure substance