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

Nucleus: The Center of an Atom

The nucleus is located at the center of an atom. It is very small and has a positive electrical charge due to the protons. The nucleus contains particles called protons and neutrons, which make up nearly all of the atom's mass.

Electron Cloud: The External Area of an Atom

The electron cloud surrounds the nucleus and is longer than the nucleus. It has an equal but negative electrical charge compared to the protons. The electron cloud contains particles called electrons, and their mass is negligible compared to the protons and neutrons.

Historical Development of Atomic Structure

In the 5th century, ancient Greeks proposed the concept of the atom. In 1808, Dalton discovered the existence of protons and electrons. In 1904,... Continue reading "Atomic Structure and Chemical Reactions: A Comprehensive Overview" »

Physical Changes: States of Matter

Changes of state are fundamental physical changes in matter, and they are reversible. These transformations occur by adding or removing energy from matter, causing it to transition from one state to another. The five states of matter include solid, liquid, gas, and the less common plasma and liquid crystal.

Defining the States of Matter

Solid State Properties

A solid is matter that can be picked up and moved from one place to another without changing its shape or size.

Liquid State Properties

A liquid is matter that changes shape when it moves from one container to another, but its volume remains constant.

Gaseous State Properties

A gas is matter whose shape and volume can change significantly by applying pressure... Continue reading "Matter's Transformations: States and Kinetic Theory" »

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" »

Fatty Acid Classification: Saturated, Monounsaturated, and Polyunsaturated

Fatty acids are the main components of triglycerides and phospholipids. They are non-polar and therefore hydrophobic. Their chains consist of covalently bonded carbon atoms with hydrogen atoms.

Saturated fatty acids contain only single bonds, meaning they are "saturated" with hydrogen. Unsaturated fatty acids, conversely, contain one or more double bonds.

Saturated Fatty Acid	Monounsaturated Fatty Acid	Polyunsaturated Fatty Acid

Cis vs. Trans Unsaturated Fatty Acid Isomers

• If hydrogen atoms are on the same side of the double bond, the isomer is cis (e.g., yellow H in diagrams). If hydrogens are on the opposite side of the double bond, the isomer is trans.
• Cis fatty acids have

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