Chemistry: Matter and Pure Substances

Chemistry

• Matter is composed of tiny particles called atoms.
• Particle movement increases with temperature.
• Temperature affects particle kinetic energy, influencing behaviour.
• Higher temperatures result in faster particle movement causing a greater volume, while lower temperatures result in slower particle movement and a smaller volume.
• The space between gas particles is typically greater than in solids and liquids.
• Higher temperatures lead to increased volume, while higher pressure compresses particles, decreasing volume.
• Different states of matter (solid, liquid, and gas) have distinct characteristics regarding shape, volume, and fluidity.
• Pure substances consist of a single substance without impurities; these have precise melting and boiling points.

Pure Substances and Mixtures

• Pure substances have a defined melting and boiling point.
• Mixtures are composed of two or more substances physically combined.
• Mixtures can have varying compositions (amounts of each substance).
• Mixtures retain their original properties after combination.
• Mixtures can be separated using physical methods such as filtration, distillation, and magnetism.

Separation Techniques

• Mechanical / Physical Separation: Separating parts of a mixture based on size differences using sieves.
• Filtration: Separating solids from liquids using a filter.
• Decantation: Separating liquids from solids by letting the mixture settle and pouring off the liquid.
• Magnetism: Separating magnetic materials from a mixture using a magnet.

Atomic Structure

• Atoms consist of protons, neutrons, and electrons.
• Protons and neutrons are located in the nucleus.
• Electrons orbit the nucleus in specific energy levels.
• Protons carry a positive charge; neutrons are neutral, and electrons carry a negative charge.
• Protons and neutrons have similar mass; electrons are virtually massless.
• Electrons fill energy levels starting from the innermost, with higher levels having more electrons.
• Atomic number identifies a specific element and is equal to the number of protons.
• Mass number determines the total mass of an atom and corresponds to the total number of protons and neutrons.

Periodic Table

• The periodic table arranges elements based on their atomic number (number of protons) in increasing order.
• Elements in the same group share similar chemical properties due to their similar electron configurations.
• The periodic table is organised into periods (rows) and groups (columns), which give useful information about the element.

Chemical Behavior

• The arrangement of electrons in an atom's electron shells determines its chemical properties and reactivity.
• The outermost electron shell (valence shell) is crucial.
• The number of electrons in the valence shell determines how easily atoms form chemical bonds.
• Elements in the same group of the periodic table tend to have similar chemical behavior due to similar valence electron configurations.
• Atoms will gain, lose, or share electrons to achieve a stable electron configuration.
• Understanding electronic arrangements helps in predicting behavior in chemical reactions and the formation of compounds.

Isotopes

• Atoms of the same element can have different masses (different numbers of neutrons in their nucleus).
• Isotopes of an element have the same number of protons and electrons but a different numbers of neutrons.
• Isotopes are named by their mass numbers (number of protons plus neutrons in that nucleus).

Physics - Waves and Optics

• Waves transfer energy through vibrations.
• Waves have properties including frequency, wavelength, amplitude, and speed.
• Wavelength is the distance between two successive crests (or troughs) of the wave, while amplitude is the height of the wave above (or below) the undisturbed position.
• Frequency is the number of oscillations or cycles per unit time, measured in Hertz (Hz).
• Wave speed is the rate at which the wave travels through a medium.

Types of Waves

• Transverse waves: particles oscillate perpendicular to the direction of the wave propagation.
• Longitudinal waves: particles oscillate parallel to the direction of the wave propagation.

Reflection, Refraction and Diffraction

• Reflection: Light or waves bouncing off a surface; The angle of incidence equals the angle of reflection.
• Refraction: Light or waves changing direction when moving from one medium to another; it is caused by a change in speed.
• Diffraction: Light or waves spreading out when passing through an opening or around an obstacle; more pronounced when the wavelength of the wave corresponds to the size of the opening, obstacle, or gap.

The Human Ear, Part 1

• Sound waves are collected into the ear canal.
• The eardrum vibrates when sound waves travel through the ear canals.
• Vibrations cause the ossicles (tiny bones) in the middle ear to vibrate and further amplify vibrations.
• The cochlea converts vibrations into electrical signals.

The Human Eye, Part 1

• The cornea initially refracts (bends) light.
• The pupil adjusts to control the amount of light entering the eye.
• The lens focuses the light onto the retina.
• The retina converts light into electrical signals that travel to the brain.

The Human Eye, Part 2

• The cornea is a tough, protective outer layer.
• The conjunctiva is a thin mucous membrane covering the white part of the eye.
• The aqueous humour is a clear liquid filling the space between the cornea and lens.
• The pupil is the opening at the centre of the iris through which light passes.
• The lens focuses light onto the retina.
• The iris adjusts the size of the pupil.
• The vitreous humour is a clear jelly-like substance filling the space behind the lens.
• The retina contains photoreceptors (rods and cones), which convert light into electrical signals to the brain.
• The fovea is a part of the retina with the highest concentration of cones.

Electromagnetic Spectrum

• Electromagnetic waves are transverse waves that travel at the speed of light.
• They differ based on their wavelengths and frequencies.
• The electromagnetic spectrum consists of radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays.
• Electromagnetic waves have properties and applications, and hazards based on specific wavelengths and frequncies.

Biological Concepts

• Digestion involves ingestion, digestion, absorption, assimilation, egestion.
• Nutrients are molecules crucial to bodily functions.
• Macro-nutrients are carbohydrates, fats, and proteins required in large amounts for energy and physiological functions.
• Micro-nutrients (vitamins, etc.) are required in smaller amounts and essential for numerous bodily processes.
• Different foods contain different levels and types of nutrients.

Photosynthesis and Respiration

• Photosynthesis converts light energy into chemical energy (glucose), releasing oxygen.
• Cellular respiration breaks down glucose to release energy (ATP), requiring oxygen and producing carbon dioxide.
• Plants utilize both photosynthesis and respiration for energy production and growth.

Cell Structure (Animal & Plant)

• Plant cells have cell walls, which provide structural support.
• Animal cells do not have cell walls.
• Both cell types have cell membranes that regulate passage of substances and other organelles such as mitochondria, vacuoles, and ER.
• Specific organelles have specific functions. A list of organelles and their functions are added.

Circulatory System

• The circulatory system transports substances throughout the body.
• Blood vessels, and the heart are crucial parts of this system and have specific purposes.
• Blood pressure is the force exerted by blood against the walls of the blood vessels; measured values are systolic and diastolic. Blood pressure factors are added.

Transport in Plants

• Xylem transports water and minerals from roots to leaves.
• Phloem transports sugars from leaves to other parts of the plants.
• Transpiration is the evaporation of water from leaves, which moves water up xylem through a mechanism called the transpiration stream.
• Translocation is the movement of sugars through phloem to various plant parts. Added information about the factors that affect the rate of transpiration is added.

Diffusion

• Diffusion is the movement of atoms or molecules from an area of high concentration to an area of low concentration.
• Temperature, surface area, and distance affect diffusion rate.
• Diffusion is prevalent in biological structures and systems as a crucial process for transport and maintenance.

Food Tests

• Specific tests (iodine, Benedict's, and ethanol emulsion) are employed for the identification and detection of specific food components, including carbohydrates, proteins, and fats.

Chemical Stoichiometry

• Balancing chemical equations involves adjusting coefficients in front of compounds ensuring similar numbers of atoms on both sides.
• The law of conservation of matter dictates that during a chemical reaction no atom is lost or gained.

Acids & Bases; pH Scale

• Acids have hydrogen ions (H+); bases have hydroxide ions (OH−).
• The pH scale measures acidity and alkalinity, from 0 (strongly acidic) to 14 (strongly alkaline); 7 is neutral.
• Indicators change colour in response to changes in pH of solutions; these are useful in chemical analysis including titration.

Titration

• Titration is an analytical technique for determining the concentration of a solution using a solution of known concentration.
• Titration follows a methodical approach to determine the point at which a neutralization reaction between a solution of unknown concentration (analyte) and a solution of known concentration (titrant) occurs.
• Calculations (MA VA = MB VB) are used to determine the unknown concentration.

Protein Synthesis

• Protein synthesis involves transcription and translation process. Each stage described in greater detail with a diagram
• Transcription: conversion of DNA sequence to mRNA (replace T with U).
• Translation: converting mRNA sequence of codons to their corresponding amino acid sequence.
• The amino acid sequence folds into a protein.

Atomic Structure Summary

• Atomic number (Z) = number of protons, which defines the element
• Mass number (A) = number of protons + number of neutrons
• Law of conservation of mass: Matter cannot be created or destroyed in a chemical reaction (numbers of atoms of each element remain the same on both sides of equation)