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

Crystalline Solids

Crystal Lattice

The main characteristic of crystalline solids is a regular and repeating pattern of constituent particles. A crystal lattice is a three-dimensional arrangement of points in space, representing the arrangement of these particles.

Unit Cells

Unit cells are the smallest repeating units in a crystal lattice. They are broadly divided into two categories:

• Primitive Unit Cells: Constituent particles are present only at the corners.
• Centred Unit Cells: Contain particles at positions other than corners, in addition to those at the corners. There are three types of centered unit cells:
  • Body-Centred Unit Cells: Contain one particle at the body-center, besides those at the corners.
  • Face-Centred Unit Cells: Contain one particle

Water: Essential Properties for Life

Polarity and Hydrogen Bonds in Water Molecules

• A water molecule comprises an oxygen atom covalently bonded to two hydrogen atoms.
• Oxygen is more electronegative than hydrogen, leading to an unequal sharing of electrons.
• This creates a polar covalent bond, with hydrogen having a partial positive charge and oxygen having a partial negative charge.
• The bent shape of water molecules results in a positive charge concentration on one side and a negative charge on the opposite side.
• The partial positive charge is attracted to the partial negative charge, creating an intermolecular attraction between water molecules called a hydrogen bond.
• Hydrogen bonds are the strongest intermolecular forces, but they are still considered

Saturated Solution

Contains the maximum amount of solute for a given quantity of solvent at a constant temperature and pressure.

Solubility

Is the amount of solute that dissolves in a given quantity of a solvent at a specified temperature and pressure to produce a saturated solution.

Unsaturated Solution

A solution that contains less solute than a saturated solution at a given temperature and pressure.

Supersaturated Solution

Contains more solute than it can theoretically hold at a given temperature.

Miscible

Forming a homogeneous mixture when added together.

Immiscible

Liquids that are insoluble in one another.

Henry's Law

States that at a given temperature, the solubility of a gas in a liquid is directly proportional to the pressure of gas above the liquid.... Continue reading "Solutions and Solubility: Key Terms and Definitions" »

Experiment:Red Cabbage Indicator

Aim:To make our own indicator.

Background information:

• The Red Cabbage is red in acid solution

• Purple is a neutral solution

• Greenish-yellow is a base solution

• Red Cabbage contains a pigment molecule called FLAVIN(antocianina).

• The red cabbage juice will work over a wide pH range.To identified substances(acid or Bases)

Conclusion:The red Cabbage works as an indicator because we could identify the changes of each substance and classifies the bu colour of pH.For that we needed the ph scale.

Experiment :Acids and Bases

Aim:To find which substances are acid and bases by using different indicators

Materials:

1. Indicators(blue and red Litmus paper)

2. Samples

Procedure:Drop one drop of each substance on the indicators(the litmus

French Grammar

Passé Composé

• Subject + avoir/être (in present) + past participle
• Verbs with être: naître, mourir, aller, venir, arriver, partir, monter, descendre, passer, retourner, entrer, sortir, rester, tomber

Verbs Pouvoir and Vouloir

• Pouvoir: peux, peux, peut, pouvons, pouvez, peuvent
• Vouloir: veux, veux, veut, voulons, voulez, veulent

Questions

• Aimez-vous votre métier?
• Est-ce que vous aimez votre métier?
• Que préférez-vous aujourd'hui?
• Qu'est-ce que vous préférez aujourd'hui?
• Comment êtes-vous devenu réalisateur?
• Comment est-ce que vous êtes devenu réalisateur?
• Quels métiers avez-vous faits?
• Quels métiers est-ce que vous avez faits?

Exercer un Métier

• Avoir de l'imagination
• Être créatif(ve)
• Organisé(e)
• Sociable
• Résistant(e)
• Rapide
• Patient(

Structure of DNA and RNA

Understandings:

The nucleic acids DNA and RNA are polymers of nucleotides.

• Nucleotides are the monomers of the polymer DNA.
• DNA nucleotides are made up of 3 components: a phosphate group (PO₄^-3), a pentose sugar, and a nitrogenous base.
• The phosphate, sugar, and base are linked by covalent bonds.
• In DNA and RNA, each nucleotide is linked to the next nucleotide between the phosphate of one and the pentose sugar of the other nucleotide.

DNA differs from RNA in the number of strands present, the base composition, and the type of pentose.

Wastewater Treatment

Sludge Density Index (SDI)

The weight in grams of one mL of sludge after settling for 30 minutes. SDI = 100/SVI.

Process Design Examples

• Complete Mix Activated Sludge (CMAS): Air is blown into the tank to keep the waste mixed with the organisms and to add oxygen to the water. This process removes soluble suspended solids (SS) and ammonia by exposing the waste to organisms.
• Sequencing Batch Reactor (SBR): This reactor operates under non-steady state conditions in a batch mode with aeration and sludge settlement occurring in the same tank. The SBR tank carries out the functions of equalization, aeration, and sedimentation in a time sequence.
• Staged Nitrification Process: Offers greater treatment efficiency and capacity than a single

Metals, Bonding, and Extraction: Key Concepts

Attractive forces in a metallic structure arise because positive ions and electrons attract each other.

High Melting Points

Why does X have a high melting point? Due to its giant covalent structure, a lot of energy is needed to break the strong covalent bonds.

Lattice Structure of Metals

Why do metals have a lattice structure? The atoms in a pure metal are arranged in closely packed layers, which makes them strong.

Alloys

Alloy: A mixture of a metal with at least one other element.

Isotopes

Isotope: An atom with a different number of neutrons.

• The more reactive the metal, the more likely it is to corrode from oxygen and water.

Ores

Ore: A rock that contains enough metal to make mining and extraction economical.... Continue reading "Metals, Bonding, and Extraction: Key Concepts Explained" »

Carbon's Versatility

Carbon is a versatile atom due to its ability to form four covalent bonds with other atoms, including other carbon atoms. This allows carbon to create a wide variety of organic molecules with diverse structures and functions.

Definitions:

• Organic Compound: A compound containing carbon that is typically found in living organisms.
• Hydrocarbon: An organic compound consisting of only carbon and hydrogen atoms.
• Macromolecule: A large molecule formed by the joining of smaller repeating units (monomers). Examples include proteins, carbohydrates, and nucleic acids.

Dehydration and Hydrolysis Reactions

Dehydration Reaction:

A dehydration reaction is a chemical reaction where water is removed from the reactants to form a larger molecule.... Continue reading "Organic Molecules: Structure and Function" »

Electronegativity

Measure of the tendency of an atom to attract bonding pair of electrons.

Cation

Ion that has a positive charge.

Ionic Bond

Chemical bond formed between two ions with opposite charge.

Anion

Ion that has a negative charge.

Chemical Bond

Electrical attraction between nuclei and valence electrons that binds atoms together.

Covalent Bond

Bond formed when atoms share one or more pairs of electrons.

Non Polar Bond

Type of chemical bond where two atoms share a pair of electrons with each other.

Polar

Uneven distribution of charge.

Polar Bond

Type of chemical bond where a pair of electrons is unequally shared between two atoms.

Molecule

Neutral group of atoms that are held together by covalent bonds.

Molecular Compound

Chemical compound whose simplest... Continue reading "Chemical Bonding and Organic Chemistry" »