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Grade 8 (M2) Science Vocabulary Studyguide for 2nd sem
 

Grade 8 (M2) Science Vocabulary Studyguide for 2nd sem

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    Grade 8 (M2) Science Vocabulary Studyguide for 2nd sem Grade 8 (M2) Science Vocabulary Studyguide for 2nd sem Presentation Transcript

    • Chapter 5- Elements Compounds and Mixtures Examples of non-metals:5.1 Elements State at Room Examples of non-metals Temperature  Element= is the simplest form of matter. It Solid Carbon, phosphorus, can’t be split up into smaller substances by iodine, sulfur physical or chemical processes. Liquid Bromine  Atom= is the smallest particle in a matter. Gas Oxygen, hydrogen,  Molecule= is made of two or more atoms. nitrogen, neon, argon, krypton, fluorine,3 Groups of Elements chlorine, helium, radon 1. Metal=is an element, compound, or alloy Properties of Metals: that is a good conductor of both electricity Have dull surfaces and heat. All metals are solid at room Brittle and snap easily temperature except mercury. Poor heat conductors Cannot conduct electricity (except carbon) Examples of metals: Have low melting and boiling points sodium, copper, iron, aluminum, gold, silver, lead, calcium, mercury, magnesium, 3. Metalloid= is a chemical element with platinum and zinc. properties that are in-between metals and non- metals, or have mixed characteristics. Properties of Metals: Have shiny surfaces. Examples of non-metals: Ductile (can be pulled into wires) boron, silicon, germanium, arsenic, antimony Malleable (can be beaten into many tellurium shapes) Good conductors of heat and 5.2 Compounds electricity Have high melting and boiling  Compound= is a pure chemical substance points which is formed when two or more elements 2. Non-metal= one of the elements which do combine chemically in a chemical reaction. not exhibit metallic properties, generally located in the corner of the Periodic Table. 1
    • Solute= a substance dissolved in another substance.5.3 Mixtures c. Distillation= is used to purify liquids. Mixture= is made up of two or more Distillate= a liquid product substances which are mixed together condensed from vapor physically ( stirring, mixing, shaking, or during distillation. dissolving) Liebig condenser= is an Examples of non-metals: instrument used to condense vapor. Mixture Component Fractional distillation= is theAir oxygen, nitrogen, inert separation of a mixture into its gases, carbon dioxide, component parts, or fractions, such microorganisms, dust, as in separating chemical water vapor compounds by their boiling point byBlood red blood cells, white heating them to a temperature at blood cells, plasma, which one or more fractions of the oxygen, carbon dioxide, compound will vaporize. nutrients, hormones, d. Chromatography= is a method of water separating and identifying mixtures.Iced lemon tea water, lemon, sugar, Types of Chromatography: tea  Paper chromatography= is used to separate the different5.4 Separation Techniques colored components in dyes. a. Filtration= is used to separate a solid from  Liquid chromatography= liquid. uses a long column packed with o Residue= solid material remaining absorbent material such as after a distillation or an evaporation, alumina. or portion of a larger molecule.  Gas chromatography= uses a o Filtrate= liquid produced after long tube with an inner gas filtering a suspension of a solid in a being pumped into it.  Liquid-liquid extraction= is also liquid. known as solvent extraction. It b. Crystallization= is a method to obtain involves the separation of two or pure solid from pure solid. more components due to their Solvent= is a substance that unequal solubility’s in 2 liquid dissolves a solute resulting in a phases. solution. 2
    • Chapter 6- Energy and Chemical Changes5.5 Radioactive Elements 6.1 Physical and Chemical Changes Radioactive Elements= are naturally Physical change= one that affects its unstable. Their nuclei disintegrate and emit physical properties such as its state (liquid, rays that are harmful to living things. gas, solid). It does not produce new Geiger counter= a special instrument that substance Chemical change= always produces one ore detects radiation. more new substances which have different physical and chemical properties comparedUses of Radioactive Elements: to the original substances. Determining the age of fossils Producing energy Some of the roles Physical and Chemical changes in Medical uses daily life: Physical Changes in Chemical Changes in Daily Life Daily Life Evaporation of sweat Photosynthesis in plants Melting of chocolates Digestion of food in our body Dissolving of sugar and Burning of fossil fuels in salt in water vehicles Freezing of water to Cooking raw food form ice 6.2 Chemical Equations Products= are new formed substances during chemical reaction. Reactants= are the original substances that are reacting together. Chemical reaction= is a process that leads to the transformation of one set of chemical substances to another. 3
    • 6.4 Factors Affecting the Rate of a Reaction Chemical equation= is the Temperature symbolic representation of Concentration=amount of a specified a chemical reaction where substance in a unit amount of another the reactant entities are given on substance. the left hand side and the product entities on the right Particle size and pressure hand side. Catalyst= a substance that changes the rate Chemical symbols= are of reaction without being changed. abbreviations that are used to denote a chemical element. 6.5 Chemical Reactions and Chemical Chemical formula= is the Substances in Everyday Life combination of the chemical symbols of the elements in the Combustion of fossil fuels substance itself. Rusting iron6.3 Energy and Chemical Reactions Photosynthesis= a natural chemical reaction that takes place in green plants Exothermic reaction= the reaction that Respiration= is another natural chemical release heat to the surroundings. reaction that takes place in all living things to Endothermic reaction= the reaction that produce energy. absorb heat from the surroundings. Examples of exothermic reaction: Combustion or burning Neutralization Reaction between metal and water Examples of exothermic reaction: Photosynthesis Decomposition by heat 4
    • Chapter 7- Forces and Motion Newtons laws of motion7.1 Understanding Force 1. First law: If an object experiences no net  Force =is any influence that causes force, then its velocity is constant: the object an object to undergo a certain change, is either at rest (if its velocity is zero), or it either concerning its movement, direction, moves in a straight line with constant speed or geometrical construction. (if its velocity is nonzero). Types of Forces: 2. Second law: The acceleration a of a body Gravitational force= the force of is parallel and directly proportional to the attraction between all masses in the net force F acting on the body, is in the universe. direction of the net force, and is inversely Magnetic force= attraction or repulsion that arises proportional to the mass m of the body, between electrically i.e., F = ma. charged particles because of their 3. Third law: When a first body exerts a motion force F1 on a second body, the second body Electrostatic force= is one simultaneously exerts a force F2 = −F1 on the between two electric charges first body. This means that F1 and F2 are Electrostatic friction= is the equal in magnitude and opposite in direction. force between two surfaces 7.2 Resultant Forces on a Same Plane (Net Force)  Spring balance= is one common instrument to measure force.  Resultant or Net force= is obtained by  Sir Isaac Newton= a great English computing the vector sum of all of the scientist and mathematician who sought to applied forces and the constraint forces describe the motion of all objects using the acting on a body concepts of inertia and force, and in doing  Parallel forces= are forces whose lines of so he found that they obey action are parallel. certain conservation laws.  Non-parallel forces= are vector forces having an angle other than zero degrees or 180 degrees direction between them. 5
    • Chapter 8- Light7.3 Resultant Forces on Static Objects 8.1 Properties of Lightand Moving Objects with ConstantVelocity Light= is electromagnetic radiation that is visible to the human eye, and is responsible Static object= is an object that is at rest, for the sense of sight. stationary and not moving. Moving object with constant velocity= Properties of light: it is not acted on by any outside force, and thats more "Newton-like" than the first Light is a form of energy. idea. It does not change speed or direction. Light travels extremely fast has a speed of _________________. Light travels in straight lines within the same medium. Light can be reflected when it hits a surface. Light can be refracted when it travels from transparent medium to another. 8.2 Reflection of Light  Reflection of light occurs when light bounces off to surface of an object.  Regular reflection occurs if all the light that hit the surface is reflected regularly, sharp images will be produced.  Irregular or Diffuse reflection occurs when a parallel beam of light hits a rough surface and that tiny bumps on the surface cause the reflected light to head up in all direction. 6
    • 8.4 Light and ColorsLight reflection application in daily life: Spectrum= band of colors in certain order. Plane mirrors are used at home in bedrooms Dispersion= is the splitting or separating of and bathrooms to help in dressing and white light into its spectrum. combing. Rainbow= is a natural phenomenon due to Two plane mirrors are used in a periscope the dispersion of light by the tiny raindrops to reflect and change the direction of light. in the air. Periscopes are used in submarines to see The color of an object depends on: things above the water. Kaleidoscope is a tube containing two or the color of the light that shines on the more plane mirrors to form beautiful object images. the color of the light that the object absorbs Convex mirrors produce a wider scope of the color of the light that the object reflects views which are used as security mirrors, blind corners on road, car wing mirror. Concave mirrors produce magnify images which are used as dental mirrors, cosmetic mirrors, microscopes, and telescopes.8.3 Refraction of Light Refraction= the bending of light when it travels into a medium of different density as its speed changes.Refraction of light makes: Things to appear to be shallower in the water Drinking straw submerged partially in water appears bent The sharp images formed on our retina 7
    • Chapter 9- Soil Types of Soil Size range Sand 0.05 mm to 2 mm Silt 0.002 mm to 0.05 mm9.1 Soil Clay Less than 0.002 mm Soil= mixtures of inorganic materials, organic materials, air, water and soil Soil structure: repeating pattern of peds organisms. Inorganic materials= are the weathered Peds= are the basic unit of soil structure. rocks which are made up of minerals combined in different ways. They are small clumps of soil that have Organic materials= are the decaying formed rock-like clumps. living matter. It could be plants or animals. Types of soil structure:Types of Soil: Clay soil= is soil with a heavy  Granular concentration of clay particles  Platy Loamy soil=soil composed of sand, silt,  Blocky clay, and organic matter in evenly mixed  Prismatic particles of various sizes  Columnar Sandy soil= is a naturally granular composed of finely Types of soil “structureless” soil: divided rock and mineral particles Soil texture=refers to the proportion of  Massive the sand, silt and clay in the soil.  Single grainSoil color: Soil consistency: refers to the ease with which an a. Dark colored soil=rich in nutrients and individual ped can be crushed by the fingers. usually contains more decomposed organic matter known as humus.( yet some certain Moist soil: conditions- dark colored soil are very poor soil) loose, friable firm b. Gray soils= can indicate poor drainage. Wet soil: c. Red soils= can indicate very poor soils plastic, sticky (some conditions, it appears rich and Dry soil: healthy) soft, hard 8
    • Weathering= is the process of breaking down of rocksSoil Profile: is the vertical display of soil layers. Types of weathering: Horizon= refers to each layer of the soil. Physical weathering= breaks down the rocksLayers of the Soil: a. Horizon O= is at the very top of the but what it is made up of stays the same. profile. Compose of organic matter lying on Chemical weathering= breaks down the the ground and usually dark in color. rocks but it may change what it is made up b. Horizon A= the soil beneath the horizon O of. and known as the topsoil. It’s usually dark 9.3 Soil Uses and Soil Improvement in color and it’s generally the most productive layer of the soil.  Soil Improvement= is the process of c. Horizon B= layer below the horizon A and making the following aspects of soil known as the subsoil. It’s usually light, favorable for plant growth. colored, dense and low in organic matter. Leaching= is the removal of Examples: organic matter, natural fertilizers and minerals that have dissolved in improving its pH value water Soil Uses: d. Horizon C= is below horizon B and consists Supports the roots of the plants and supplies mostly of big rocks which after weathering, nutrients to the plants. gives rise to the horizon above it. Soil contains minerals such as metals and petroleum that can be used to make things.9.2 Soil Formation Soil prevents floods and droughts by absorbing water and releasing it later.Factors of soil formation: Soil is the habitat for many living things. Parent material ( texture, structure, Soil will loose its fertility and usefulness due chemical, and rock composition) to human and natural factors. Climate Topography Biotic (plants and animals) Time 9
    • Chapter 10- The Earth b. Sedimentary Rocks= are rocks formed10.1 Layers of the Earth by consolidated sediment deposited in layers. a. Crust= is the thinnest layer and is made up They contain fossils. Examples: (limestone, of rocks and minerals. conglomerate, sandstone) b. Mantel= is the thickest and is made up of silicon, oxygen, aluminum and iron Sediment= is a naturally occurring c. Outer core= is made up of molten iron and material that is broken down by nickel processes of weathering and is d. Inner core= is made up of solid iron. subsequently transported by the action of wind, water, or ice, and/or10.2 Rocks by the force of gravity acting on the particle itself. Rocks =are a naturally occurring solid aggregate of one or more minerals or c. Metamorphic Rocks= are formed due to mineraloids. great pressure and heat. Examples; (slate, marble)Types of Rocks: Weathering= the process that breaks down a. Igneous rocks= are formed when magma, rocks into smaller pieces. the molten rock, cools and solidifies. Magma= is made up of melted 2 types of weathering: minerals 1. Mechanical weathering= breaks Intrusive igneous rock= are down rocks without changing their formed from magma that cools and chemical composition. solidifies within the crust of a 2. Chemical weathering= involves planet. Example: granite chemical reaction. It’s the process by Extrusive igneous rocks= form which rocks are decomposed, dissolved when magma makes its way to or loosened by chemical processes to Earths surface. The molten rock form residual materials. erupts or flows above the surface as lava, and then cools forming rock. Examples: Obsidian, Basalt, Pumice 10
    • 10.4 Fossil Fuels Fossil fuels= are hydrocarbon compounds formed from the decay of organic matter Erosion= is a process that wears down over 300 years ago. rocks and moves them away to other Coal= is a type of fossil fuel, from decayed places. plants in swampy areas which were Major erosion agents are: subjected to great pressure and heat for wind, waves, running water, glaciers million of years. 4 types of Coal: Rock cycle= is the cycle in which rocks are a. Bituminous coal b. Anthracite coal formed, broken down and formed again. c. Sub-bituminous coal d. Lignite coal10.3 Minerals Petroleum= is a type of fossil fuel from decayed animals and plants in the oceans Minerals= is a naturally occurring, which were subjected to great pressure and inorganic solid crystals with definite heat for million years. chemical composition. Oil shale= is sedimentary rocks that contain Native minerals= are minerals which are solid bituminous materials that released as composed of only one element. petroleum-like liquid when they are Gems= are rare and expensive minerals processed. which are jewelry. Ore= contain minerals that can be used to 10.5 Fossil Fuels make useful substances. Water=is the most essential element to life on Earth.Physical properties of Minerals: Hydrosphere= is the total water system surrounding our planet. Color Underground water= is water that comes Luster= is the way a minerals reflects light. from the ground. Streak= is the color of the mineral when it Water table= is the level underground is rubbed across a hard surface. which is saturated with water. Cleavage occurs when a mineral breaks to Aquifer= a large deposit of underground form smooth flat surfaces. water. Specify gravity of a mineral= is the Surface water= are waters in lakes in relative weight compared to an equal rivers or oceans. volume of water. Hardness= is the measures of how easy a mineral can be scratched. 11
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