Science Notes PDF

ELECTRICAL SWITCH: A device that controls the flow of electric current through a circuit. In an open circuit, a light will be off; in a closed circuit, a light will be on. ELECTRIC CURRENT: A continuous flow of electric charges moving from one place to another along a pathway; required to make all el...

ELECTRICAL SWITCH: A device that controls the flow of electric current through a circuit. In an open circuit, a light will be off; in a closed circuit, a light will be on. ELECTRIC CURRENT: A continuous flow of electric charges moving from one place to another along a pathway; required to make all electrical devices work; measured in amperes (A). ELECTRICAL ENERGY: The better term for electricity; the form of energy that consists of a flow of electric charges as the energy is transferred through a conductor. BIOMASS ENERGY: Energy created by burning any type of plant or animal tissue to heat water and create steam, which turns turbines and generates electricity. BATTERY: An energy source that uses a chemical reaction to create an electric current. BALANCED FORCES: When the total of all forces on an object equals zero and the object’s motion does not change. MATERIALS AT HOME VITAMINS: The organic compound that is required as a nutrient by an organism and is often obtained from its diet. The deficiency of vitamins can cause many diseases and illness in the organism. NUTRIENT: Molecules that can be used by cells or living organism to extract energy through metabolic processes. Although nutrients are often sought off only as energy providers, they can also be used as molecular building block for the biosynthesis of cellular structures ETHANOL: A flammable, colourless, slightly toxic chemical compound with a distinctive perfume-like odour. Also known as ethyl alcohol, drinking alcohol, or grain alcohol, in common usage it is often referred to simply as alcohol. ANTIOXIDANT: A molecule that protects cells from oxidative damage of oxygen and free radical molecules that are chemically unstable and cause random reactions damaging proteins, nucleic acids, and cell membranes. Examples of dietary antioxidants are vitamins C, E, and K, and diverse plant products such as lycopene AMINO ACID: Building block of proteins and enzymes. Dietary proteins need to be broken into their amino acid components before they can be used by the body. Note that there are 20 amino acids found in proteins. Many nutritional lists describe only 18 occluding glutamine and asparagine. Their values are included in those reported for the acidic forms glutamate and aspartate. ACID: A sour tasting, corrosive substance - the opposite of a base substance. Acidic solutions will turn litmus red. AEROSOL: Liquid or solid particles that are suspended in air or a gas. Also referred to as particulate matter. VOLATILE: Compounds with low melting temperatures, such as hydrogen, helium, water, ammonia, carbon dioxide and methane. ACIDIC: A term used to describe a solution that has a value below 7 on the pH scale; the more acidic a solution, the lower its pH value. SUSPENSION: A cloudy mixture in which clumps of a solid or droplets of a liquid are scattered throughout a liquid or gas. For example, muddy water is a suspension. SUPERSATURATED: A solution that is more than saturated; using temperature changes, a solution is forced to dissolve more of the substance (the solute) than would normally be found in a saturated solution. Solute: The smaller part that is put into a solution. A solute is mixed with a solvent to form a solution. SOLUTION: A homogeneous mixture of two or more substances that combine so that the mixture is the same throughout and the properties of the substances blend. SOLUBILITY: The ability of a substance (the solute) to dissolve in another substance (the solvent). Temperature plays an important role in solubility. For example, you can dissolve more orange- drink crystals in warm water than in cold water. SATURATED: A solution that contains as much of one substance (the solute) as can be dissolved in another substance (the solvent). For example, when you cannot dissolve any more drink crystals in water, the solution is saturated. PURE SUBSTANCE: A substance that is composed of only one type of atomic particle and therefore always has the same properties. There are two kinds of pure substances: elements and compounds. PH SCALE: A scale that measures the acidity of substances in solution; has numbers from 0 (strongly acidic) to 7 (neutral) to 14 (strongly basic). NEUTRAL PH: Neither an acid nor a base. On the pH scale, a neutral substance or solution has a pH value of 7. Pure distilled water has a pH of 7. EMULSION: A special kind of suspension that has been treated to prevent the parts of the mixture from separating. For example, homogenized milk is an emulsion. DISSOLVE: To completely mix one substance (the solute) in another (the solvent) to form a solution. For example, if you add sugar to water, the sugar dissolves in the water. DILUTE: A solution that has a low concentration of the dissolved substance (the solute). BASIC: A term used to describe a solution that has a value above 7 on the pH scale; the more basic a solution, the higher its pH value. BASE: A compound that produces hydroxide (OH-) in water. A solution that is basic turns red litmus paper blue because it has less hydrogen ions. THE EARTH AND ITS COMPONENTS TROPOSPHERE: The lower region of a planetary atmosphere where convection keeps the gas mixed and maintains a steady increase of temperature with depth. Most clouds are in the troposphere. STRATOSPHERE: The cold region of a planetary atmosphere above the convecting regions (the troposphere), usually without vertical motions but sometimes exhibiting strong horizontal jet streams. LITHOSPHERE: Equivalent in part to the crust, the lithosphere comprises of a number of tectonic plates that 'float' on the asthenosphere.\ ATMOSPHERE: The blanket of air that surrounds the Earth. It is thickest near the ground and gradually fades away to nothing in outer space. BIOSPHERE: The parts of Earth where life can be found, from mountaintops to the deepest parts of the ocean. SUBDUCTION: The process in which one plate is pushed downward beneath another plate into the underlying mantle when plates move towards each other. SUBDUCTION ZONE: A place on Earth’s crust where high pressure pushes an oceanic plate under another, converging tectonic plate. PLATE TECTONICS: A concept stating that the crust of the Earth is composed of crustal plates moving on the molten material below. The theory that the surface of Earth consists of large plates that are continually moving. CRUST: The outermost rock layer, divided into continental and oceanic crust. The continental crust is 25-90 km thick and is mostly granite and andesite. The oceanic crust is 6-11 km thick and mostly basalt. thin, outer layer of Earth; made of solid rock. The crust “floats” on the inner layers of Earth because it is made of lighter materials than the lower layers ASTHENOSPHERE: Ductile rocks that lie from below the lithosphere to 250 km below the surface.