Chemical Reactions and Gas Tests

• Effervescence is the production of gas in a chemical reaction, often seen as bubbling or fizzing.
• Hydrogen gas production can be confirmed by a 'squeaky pop' sound when a burning splint is placed near the gas.
• Oxygen gas can be identified if a glowing splint relights when placed near the gas, as oxygen supports burning.
• Carbon dioxide turns lime water cloudy, which serves as a test for its presence.
• Oxygen content in the air is approximately 21%, while nitrogen accounts for about 78%.
• During chemical reactions, matter is conserved, meaning the total mass of reactants equals the total mass of products.
• Exothermic reactions release energy, often as light, sound, or heat, leading to a temperature increase.
• Endothermic reactions absorb energy from their surroundings, resulting in a temperature decrease.
• Combustion is a chemical reaction where a substance reacts with oxygen, forming an oxide, and is also known as oxidation.

Incomplete Combustion

• Incomplete combustion occurs when there is insufficient oxygen, leading to the formation of carbon monoxide (CO) and soot instead of carbon dioxide.
• Carbon monoxide is a poisonous, hard to detect gas.
• Soot consists of fine carbon particles that can cause respiratory issues.

Environmental Impacts

• Burning fuels with sulfur impurities produces sulfur dioxide.
• Internal combustion engines can form oxides of nitrogen from nitrogen and oxygen in the air.
• Sulfur dioxide and nitrogen oxides dissolve in clouds to form sulfuric and nitric acids, contributing to acid rain.
• CFCs (chlorofluorocarbons) formerly used in aerosols, polystyrene production, refrigerators, and air conditioners, deplete the ozone layer when released into the atmosphere.
• Ozone layer depletion increases exposure to harmful ultraviolet radiation from the Sun.
• A 'carbon footprint' describes the impact of releasing carbon dioxide and other greenhouse gases on the environment.
• The 'fire triangle' illustrates the three components needed for burning: fuel, heat, and oxygen.

Light and Reflection

• Opaque surfaces either reflect or absorb light, not allowing it to pass through.
• Transparent surfaces allow all light to pass through.
• Translucent surfaces absorb some light and allow some light to pass through.
• Light travels in straight lines, a principle known as rectilinear propagation.
• Shadows are formed when opaque objects block light, though some light may bend around the object.
• Dispersion is the splitting of white light into its constituent colors.
• Red light refracts the least, while violet light refracts the most.
• White light consists of different colors that travel at varying speeds through glass.
• Mixing two primary colors equally results in secondary colors such as magenta, yellow, and cyan.
• Mixing all three primary colors equally produces white light.
• Black is perceived when no light is present.
• A light filter transmits only one color of light, absorbing all others.
• Mirrors have smooth surfaces that reflect light directly, known as specular reflection.
• Rough surfaces scatter light randomly, creating diffuse reflection.
• Images in plane mirrors are laterally inverted, the same size as the object, and appear to be as far behind the mirror as the object is in front, classifying them as virtual images.
• Virtual mirror images are formed using virtual rays in a location that light rays do not actually reach.
• Convex mirrors curve outwards, diverging reflected rays.
• More curved mirrors have a focal point closer to the mirror and greater divergence.
• Concave mirrors curve inwards, converging rays to focus on a point.
• Concave mirrors can form both real and virtual images.

Refraction

• Refraction occurs when light passes from one substance to another.
• When light passes from air into glass, it slows down because glass is more optically dense, causing it to bend towards the normal line.
• When light leaves glass and enters air, it speeds up and bends away from the normal line.
• A higher refractive index indicates a material is more optically dense.
• Total internal reflection (TIR) occurs when the angle of incidence is too large, causing the light to reflect within the substance instead of refracting.
• The critical angle is the minimum angle at which TIR occurs.
• Substances with a larger refractive index have a smaller critical angle.

Anatomy

• Organs consist of tissues, which are groups of cells working together, and each organ has a specific role in the life processes.
• The body contains eleven organ systems, each responsible for specific functions.
• The breathing system facilitates oxygen intake for respiration and removes carbon dioxide.
• The circulatory system, with the heart, transports blood and gases through blood vessels.
• The digestive system breaks down food, absorbs nutrients, and eliminates waste.
• The reproductive system produces gametes and enables offspring production.
• The skeletal system supports the body, protects organs, and collaborates with the muscular system for movement.

The Skeletal System

• The skeleton comprises 206 bones and provides support, protection, movement, and blood cell production in the bone marrow.
• Bones connect at joints, held together by ligaments.
• Fixed joints allow no movement.
• Cartilaginous joints allow some flexibility.
• Synovial joints allow different types of movement.
• Pivot joints allow twisting but not bending.
• Ball-and-socket joints allow movement in almost any direction.
• Hinge joints allow folding movement in one direction
• Condyloid joints can be flexed or extended.
• Muscles are attached to bones via tendons and work in pairs to facilitate movement.
• The agonist muscle contracts while the antagonist muscle relaxes.

The Circulatory System

• The circulatory system is a network of blood vessels that transports blood.
• The heart is a double pump, circulating blood to the lungs and then to the rest of the body.
• Deoxygenated blood flows from the right atrium to the right ventricle and then to the lungs via the pulmonary artery.
• Oxygenated blood returns to the heart's left atrium through the pulmonary vein, passes to the left ventricle, and is pumped to the body via the aorta.
• Deoxygenated blood returns to the right atrium via the vena cava.
• Arteries carry blood away from the heart, carrying oxygenated blood (except the pulmonary artery), and have thicker walls due to higher pressure.
• Veins carry blood towards the heart, carry deoxygenated blood (except the pulmonary vein), and have valves to prevent backflow.
• Capillaries facilitate gas exchange between blood and organs through their thin walls.

The Respiratory System

• The breathing system takes on oxygen and removes carbon dioxide.
• Air passes through the trachea and branches into bronchi, then bronchioles, ending in alveoli.
• During inhalation, the diaphragm contracts and intercostal muscles expand the rib cage.
• During exhalation, the diaphragm relaxes and intercostal muscles relax reducing the rib cage
• A symptom is a way in which the body displays that it has a disease
• Tears and sweat contain bacteria-killing enzymes protecting the eyes and skin.
• Ears are protected by bacteria-killing wax.
• Breathing organs produce mucus to trap microbes.
• Stomach acid kills ingested microbes.
• Platelets seal wounds.
• Skin acts as a physical barrier from pathogens.
• Airways are lined with mucus and ciliated epithelial cells.
• Cilia move mucus to the nose or gut to eliminate microbes.
• Skin is a barrier because it is not too moist, and slightly acidic.
• Platelets form clots; fluid from blood fight against microbes

Immune System

• The immune system destroys microbes using white blood cells (phagocytes) to form antibodies.
• Phagocytes trap and break down pathogens, using digestive enzymes and expelling waste.
• Antibodies are proteins that stick to the microbes surface, dissolve them, make them stick together and disarm the toxins
• Memory cells recall past antigens and produce antibodies quickly for future invasions.
• Passive immunity is when a baby becomes immune via the placenta or breast milk,
• A vaccine immunizes against diseases using antigens, weak microbes, or harmless toxins, stimulating antibody production.
• Active immunity is when the body produces new antibodies to fight antigens by a vaccine injection

Drugs

• A drug is a chemical that changes how the body works
• Recreational drugs are for fun, but have dangerous effects.
• Medicines cure illness or relieve symptoms, but can be unsafe
• Depressants slow down reaction times and affect concentration.
• Stimulants increase alertness, reaction times, heart rate, and blood pressure.
• Hallucinogens cause hallucinations and can lead to unusual thoughts, numbness, confusion, memory loss, anxiety, and aggression.
• Nicotine in tobacco products is addictive and can cause heart disease.
• Tar damages alveoli and bronchi.
• Carbon monoxide reduces oxygen transport in the blood.
• Smoke damages cilia in the airways.
• Alcohol is a depressant that slows reaction times and can damage the liver.
• Excessive alcohol consumption can damage the liver.