Notes, summaries, assignments, exams, and problems for Chemistry

1. Structure of an atom -  An atom is composed of protons, electrons, and neutrons. The entire mass of an atom is concentrated in the nucleus which is at the centre.

   1. Protons - Protons are the positively charged particles which are present in the nucleus of an atom.

   2. Neutrons - Neutrons are the particles in an atom that have a neutral charge. 

   3. Electrons - An electron is a negatively charged subatomic particle that can be either bound to an atom or free

   4. Atomic Mass (what it represents) - The atomic number refers to the number of protons in the atom's nucleus, 

   5. Atomic Number (what it represents) - The atomic mass of an element represent the average total mass of its neutrons, protons, and electrons

2. Standard Atomic Notation

   1. How to determine how many neutrons,

Three major characteristics of life

The cell theory

Three major domains of life

Ethers and Epoxides: Reactions, Properties, and Applications

1. Boiling Point Difference: Ethanol vs. Dimethyl Ether

Question: Which provides the best explanation for the large boiling point difference between ethanol (b.p. 78 °C) and dimethyl ether (b.p. -25 °C)?

Correct Answer: The difference in hydrogen bonding (H-bonding).

Note: The molecular weight of both ethanol and dimethyl ether is 46. The significant difference in boiling points is due to ethanol's ability to form strong intermolecular hydrogen bonds, which dimethyl ether cannot.

2. Utility of Crown Ethers

Question: Crown ethers are especially useful for:

Correct Answer: Complexing with metal cations.

3. Product of Cyclohexene and Peroxybenzoic Acid

Question: What is the product of the reaction... Continue reading "Ethers and Epoxides: Reactions, Properties, and Synthesis Mechanisms" »

Ductility: Able to undergo change of form without breaking

·Malleability: capable of being shaped, as by Hammering or pressing:

·Density (give an Example): a measurement of how Tightly matter is crammed together. Example: Oil floats on vinegar because Its density is less.

• Chemical properties of matter (give an Example): Are any of the properties Of matter that may only be observed and measured by performing a chemical change or chemical Reaction. Example: oxidation states

·What is a physical Change (give an example): A usually reversible change in the physical 

properties of a substance,as size or shape. Example: When melting an ice cube.

·Difference between Chemical properties and physical properties (give an example)

Ionic Bonding

Bonding between a non-metal and a metal where electrons are transferred from the metal to the non-metal. This results in the non-metal forming a negative ion and the metal forming a positive ion. The structure is a giant ionic lattice with strong electrostatic forces between ions. A lot of energy is needed to break these forces, resulting in high melting and boiling points. Ionic compounds conduct electricity when aqueous or molten, as the ions are free to move around. They can be represented using dot and cross diagrams.

Covalent Bonding

Bonding between two non-metals. Covalent compounds do not conduct electricity as there are no charged particles. Small molecules are liquids or gases at room temperature due to weak intermolecular... Continue reading "Chemical Bonding and Structure" »

Thompson: A Marxist Historian

Thompson was a historian with a Marxist background whose interest in radical political works sets him apart from other authors we studied. He, like Hoggart, followed culturalism, a perspective that stresses human agency, or the active production of culture and not its passive consumption. His book The Making of the English Working Class really embodies the term, since in it he traces the development of the English working class between 1780 and 1832, more or less the time encompassed by the Industrial Revolution. The book can be seen as a rescue operation of the members (especially radicals) of the working class lost in a history led by the deaths of monarchs, statesmen, military leaders, and politicians. These... Continue reading "The Making of the English Working Class: A Radical Perspective" »

Alkali Metals

Lithium

• Lithium is harder than other alkali metals.
• It has higher melting and boiling points than other alkali metals.
• It is the least reactive alkali metal.
• It is a strong reducing agent compared to other alkali metals.
• It is the only alkali metal that forms its monoxide.
• It is not capable of forming solid hydrogen carbonates, unlike other alkali metals.
• It does not react with ethyne to form ethynide, while other alkali metals do.
• It reacts slowly with bromine compared to other alkali metals.
• It is the only alkali metal that reacts with nitrogen to give lithium nitride (Li₃N).

Alkaline Earth Metals

Beryllium

• Beryllium is harder than other members of its group.
• It has higher melting and boiling points than other members of its group.
• Its electronegativity

Heat vs. Enthalpy

Enthalpy is a property of a system, sometimes termed "heat content." It represents the system's internal energy (U) plus the product of pressure and volume (pV).

Heat is energy in transit, transferred between systems. Enthalpy (H) is a state function defining the system's state.

Hess's Law and Enthalpy

Hess's law states that the total enthalpy change for a multi-step reaction equals the sum of enthalpy changes for each individual step. This principle, grounded in the conservation of energy, allows for calculating ΔH even when direct measurement is impossible. It enables the determination of standard enthalpies of formation, useful for designing complex syntheses.

Enthalpy and Reaction Types

Enthalpy determines whether a reaction... Continue reading "Heat vs. Enthalpy, Hess's Law, Reaction Types, and Chemical Properties" »

^{Correction fluid is a white liquid. The organic solvent was originally used as an ingredient in the product. This solvent is readily absorbed by the lungs via inhalation. It has been replaced by a safer alternative for painting over mistakes. A brush (which was later replaced by a foam applicator) is attached to the cap, so when the bottle is closed, the brush is immersed in the fluid. When unscrewed, the brush is covered in liquid which is then painted over the mistake. However, it is still possible to see that the product has been used, and also the original content if the paper is held up to a light.}

Functions of Language

• Expresiva or emotiva: expresses feelings
• Funcion apelativa: incites the receiver
• Representativa: provides information
• Poetica