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CRCT Practice S8P1. Students will examine the scientific view of the nature of matter. a. Distinguish between atoms and molecules. – are the basic building block of all matter. Atoms Each kind of atom is an element – a pure substance that cannot be broken down into simpler substances. There are 117 confirmed elements. 90 of these are found in nature and the rest are synthetic (man made) Location Charge Mass Nucleus + 1 amu Neutron Nucleus 0 1 amu Electron Electron Cloud - Less than 1 amu Proton Number – describes the number of protons in the nucleus of the atom. Atomic Mass – equal to the number of protons plus the number of neutrons in the atom. Atomic – occurs when electrons equal protons. Neutral Atom A molecule is the smallest unit of a compound that has all the properties of the compound. A subscript is a small number that tells you the number of atoms of each element in the substance. b. Describe the difference between pure substances (elements and compounds) and mixtures. An element is an pure substance that cannot be broken down into simpler substances by ordinary chemical means. Compounds are pure substances that are created when atoms are chemically combined. Mixtures form when two or more substances combine without joining together chemically. Heterogeneous mixtures – look different throughout Homogeneous mixtures – look the same throughout c. Describe the movement of particles in solids, liquids, gases, and plasmas states. A state of matter is the physical form in which matter exists. A solid is a substance with definite shape and volume Particles are densely packed Energy binding the particles is very strong A liquid is a substance that Has no definite shape Has definite volume Particles are less densely packed and can flow around each other Energy binding the particles is strong A gas is a substance that has NO definite shape No definite volume The particle arrangement is far apart The binding energy is very weak. Plasma is a state of matter that forms when temperatures are high enough to remove electrons from their atoms. d. Distinguish between physical and chemical properties of matter as physical (i.e., density, melting point, boiling point) or chemical (i.e., reactivity, combustibility). Physical Properties are characteristics that can be observed or measured without changing the identity. Chemical Properties are characteristics that describes how a substance will interact with other substances during a chemical reaction. e. Distinguish between changes in matter as physical (i.e., physical change) or chemical (development of a gas, formation of precipitate, and change in color). Change – alters the physical properties of a substance without changing the identity of the substance. Physical Change – occurs when a substance is changed into a new substance with different properties. Chemical f. Recognize that there are more than 100 elements and some have similar properties as shown on the Periodic Table of Elements. The periodic table is a chart that organizes the information about all of the known elements according to their properties. – Horizontal Rows (7) Groups – Vertical Columns (18) Periods Elements in the same group have similar properties. These properties are a result of their identical valence electron numbers. – describes how likely an element is to form bonds with other elements. Reactivity Most chemically active are group 1 elements. (Due to their 1 valence electron) Group 18 (Noble Gases) are inert. This means they cannot not form bonds with other elements because they are chemically stable. Elements on the left are metals (except H) Elements on the right are nonmetals Elements along the stair step line are metalloids g. Identify and demonstrate the Law of Conservation of Matter. The law of conservation of matter states that during a chemical reaction, matter cannot be created or destroyed. Mass of the reactant equals the mass of the product A coefficient is a number that can show how many molecules of a compound are present. S8P2. Students will be familiar with the forms and transformations of energy. a. Explain energy transformation in terms of the Law of Conservation of Energy. Law of Conservation of Energy – Energy is not created or destroyed but can be transferred. Examples of Energy Transformations: Plants convert electromagnetic energy from the sun into chemical energy through photosynthesis Eating vegetables allows your body to convert stored chemical energy into thermal energy to maintain body temp and mechanical to allow you to move The sun converts nuclear energy into electromagnetic and thermal energy b. Explain the relationship between potential and kinetic energy. Kinetic energy – the energy of “motion” Depends on mass and velocity Greater the mass; Greater the KE Greater the velocity; Greater the KE Potential energy – stored energy Ex. Chemical Potential – energy stored in chemical bonds Elastic Potential – energy stored in stretched or spring objects Gravitational Potential – energy stored in objects above Earth’s surface c. Compare and contrast the different forms of energy (heat, light, electricity, mechanical motion, sound) and their characteristics. Each form of energy has its own characteristics. Mechanical – Associated with energy of motion (kinetic). Thermal Energy – total amount of energy in all the particles Heat – thermal energy that’s transferred from high to low temperature Chemical Energy – energy stored in chemical bonds Electrical Energy – energy that results from moving charges Electromagnetic – energy resulting from the motion of atoms •Light, X-rays, Microwaves, UV Sound Energy – energy given off by a vibrating object Nuclear Energy – energy stored in the nucleus of an atom •Released through Fission and Fusion d. Describe how heat can be transferred through matter by the collisions of atoms (conduction) or through space (radiation). In a liquid or gas, currents will facilitate the transfer of heat (convection). Temperature is the measure of the average kinetic energy of particles. Heat is the transfer of thermal energy between objects at different temperatures Flows from higher temperature to lower temperature Heat can be transferred through matter in all three phases and can be transferred through a vacuum (empty space). Conduction – Heat is transferred through solids and liquids by direct contact of the particles. Convection – Heat is transferred through fluids (liquids and gases) by currents. Radiation – transfer of heat without matter – uses electromagnetic waves. S8P3. Students will investigate relationship between force, mass, and the motion of objects. a. Determine the relationship between velocity and acceleration. – a push or a pull sometimes resulting in motion. Force Point – a generally stationary point such as a tree, or street sign that allows you to define the motion of an object in terms of speed, position, and direction. Reference Speed – how fast the object moves. Speed = distance / time Units – m/s Distance/Time Graph: Distance on the Y-axis Time on the X-axis – speed of the object in a given direction. Velocity changes when the speed or the direction of an object changes. Velocity – the rate at which velocity changes. Acceleration changes if the speed or its direction changes. Formula: a = vf – vi t Units – m/s/s Acceleration b. Demonstrate the effect of balanced and unbalanced forces on an object in terms of gravity, inertia, and friction. Force – the sum of the forces acting on an object. Net Forces – equal forces acting in opposite direction Net force equals zero Balanced Unbalanced Forces Net force is greater than zero Object moves in the direction of the greater force Can cause a change in the motion of an object – an object’s resistance to a change in motion. Greater Mass – Greater Inertia Inertia – the force that opposes the motion of an object Friction Static – no motion Sliding – objects sliding past each other Rolling – objects rolling past each other Fluid – friction from a liquid or gas – force of attraction between all objects. Depends on Mass and Distance Gravity c. Demonstrate the effect of simple machines (lever, inclined plane, pulley, wedge, screw, and wheel and axle) on work. – when a force is applied to an object and the object moves in the direction of the force. W = F x d Only occurs when the object moves in the direction of the force Work Machines – makes work easier by: Multiplying effort force Changing direction of force Increasing Distance 6 Simple Machine Levers Pulleys Wheel and Axle Inclined Plane Wedges Screws – a bar that is free to pivot about a fixed point Force Applied – Effort Force Resistance – Load Lever 3 classes of Levers – a rope or chain wrapped around a wheel Makes work easier by changing direction of the force Block and Tackle pulleys multiply effort force Pulley and Axle – consists of two wheels of different sizes. Larger – Wheel Smaller – Axle Makes work easier by increasing the effort force Wheel Plane – a straight, slanted surface Makes work easier allowing you to use less effort over a greater distance Incline – an inclined plane that is wider or thicker at one end than the other Makes work easier by changing the direction of the effort force Wedges – an inclined plane that is wrapped around a cylinder Makes work easier by increasing the number the threads Screw S8P4. Students will explore the wave nature of sound and electromagnetic radiation. a. Identify the characteristics of electromagnetic and mechanical waves. – any disturbance that transfers energy through matter or space. Wave – the material through which waves can travel Medium Mechanical Wave - a wave that needs a medium Transverse Wave – a wave that transfers energy in a direction that is perpendicular to its medium. Longitudinal Wave –particles move back and forth. Electromagnetic Wave – A wave that doesn’t need a medium through which to travel b. Describe how the behavior of light waves is manipulated causing reflection, refraction diffraction, and absorption. When a wave hits an obstacle, passes from one medium to another, or hits another wave, it is possible that it will change speed, direction, or shape. – occurs when a wave bounces back after striking a barrier. Sound Reflection = Echo Light Reflection in mirror allows you to see yourself Reflection Refraction - the bending of a wave as it passes at an angle from one medium to another. Light Refracts (bends) •Enters a lens •Enters a prism •Enters water from air (bent pencil) – refers to the bending, spreading, and interference of waves when thy go through a narrow opening. When waves pass through a slit, a pattern of ripples forms in all directions Diffraction Interference – when two waves collide Constructive – crest hits crest Destructive – trough hits trough – passing of waves through a medium Transparent– most of light transmits through the material •Windows, Plastic Wrap Transmission Absorption disappearance of an EM wave into a medium Opposite of Reflection You see different colors due to reflection and absorption •An apple looks red b/c all colors but red are absorbed and red is reflected back to your eye c. Explain how the human eye sees objects and colors in terms of wavelengths. Your ability to see involves the reflection of light. The Eye Cornea – transparent material helps move light into the eye Pupil – small hole that adjusts size in order to control amount of light entering Lens – responsible for focusing light Retina – where the light rays focus the image Optic Nerve – relays information about image to brain Spectrum – collection of all EM frequencies Radio waves – longest wavelength, lowest frequency •Used in AM & FM broadcasting Electromagnetic Microwaves – More energy than radio waves. •Radar Infrared Light – associated with heat. Visible Light – only part of spectrum that you can see •Longest Wavelength is Red •Shortest Wavelength is Violet •You see color because of the way light interacts with an object. Ultraviolet Light – have a higher frequency than visible light •Can cause reactions: tan the skin, too much may lead to skin cancer X-rays – can travel through soft tissue, such as skin, but not through hard bone. Gamma Rays – have the shortest waves and highest frequencies •Most Energy on Spectrum d. Describe how the behavior of waves is affected by medium (such as air, water, solids). In order to see any object, it must give off light. Luminous – objects that emit their own light Illuminated – objects that reflect light to your eyes •Amount of reflected light depends on the surface. (Smooth reflects more light than rough surfaces.) of Reflection – the angle at which any wave strikes a reflecting surface is equal to the angle at which the wave is reflected Law – material that permits light to pass through Translucent – material transmits some light Opaque – allow no light to pass through (Wood, Carpet) Transparent e. Relate the properties of sound to everyday experiences. Sound is a form of energy produced by vibrating objects. Mechanical Wave (needs a medium) Longitudinal Wave (moves back and forth) – highness or lowness of a sound Frequency – number of waves that pass a fixed point in a given time period Pitch Human Ear Outer – collects sounds Middle – transfers energy into inner ear by vibrating the 3 small bones Inner – cochlea stimulates nerve cells and sends signal to auditory nerve. Effect – change in the frequency of a sound due to a moving sound source or a moving listener Resonance – ability of objects to pick up the frequency of a nearby object Doppler f. Diagram the parts of the wave and explain how the parts are affected by changes in amplitude and pitch. – is a measure of wave energy. Height of the wave Amplitude – the distance between two successive points on a wave Crest to Crest or Trough to Trough Compression to Compression Rarefaction to Rarefaction Wavelength – the number of waves produced in a given amount of time Higher Frequency = Shorter Wavelength Lower Frequency = Longer Wavelength Frequency – refers to the highness or lowness of a sound. Determined by the frequency of the sound. •Low Pitch = Low Frequency •High Pitch = High Frequency Pitch Speed – speed at which a wave travels Wave Speed = wavelength x frequency Affected by : •Medium through which wave is traveling. Mechanical Waves travel fastest through solids Electromagnetic Waves travel at the same speed S8P5. Students will recognize characteristics of gravity, electricity, and magnetism as major kinds of forces acting in nature. a. Recognize that every object exerts gravitational force on every other object and that the force exerted depends on how much mass the objects have and how far apart they are. – an attractive force that works to pull objects together. Law of Universal Gravitation – the force of gravity acts between all objects in the universe Gravity Gravitational Force depends on: Mass – amount of matter Distance Greater the Mass; Greater the gravitational attraction Closer Distance; Greater gravitational force Newton’s st 1 Law of Motion – an object in motion stays in motion, an object at rest stays at rest unless an unbalanced forces act on it. – tendency of an object to resist a change in its motion. Greater Mass; Greater Inertia Inertia The moon is able to continuously orbit Earth because the Moon’s inertia and Earth’s gravity are balanced. b. Demonstrate the advantages and disadvantages of series and parallel circuits and how they transfer energy. Electrical Energy is produced by the movement and distribution of charged particles from the atom. Current – the flow of electric charges. Unit – Ampere (A) Electric Potential Difference (aka Voltage) – results from the differences in electrical charges in two locations. Unit = Volts (V) – a path through which electricity can flow. Energy Source – “push” charges through circuit (battery – greater voltage; greater “push”) Circuits Load – operates using electrical energy (“light bulbs”) Conductors (Wire) – material that allows electrical energy to flow easily Circuit – a circuit that provides one possible path for the e- to flow One bulb burn out – all bulbs burn out Series All loads share the same energy source •More bulbs added; dimmer lights get Circuit – offers more than one path for the flow of electricity. Each load has its own closed pathway If one bulb burns out; the others are unaffected Loads do not share a current. Parallel c. Investigate and explain that electric currents and magnets can exert force on each other. Force – a push or a pull that is exerted by a magnet Magnets have 2 poles – north and a south pole Cutting a magnet in half gives you two smaller magnets with a N & S pole. Magnetic Field – area surrounding a magnet in which the magnetic force exists Lines extend from one pole of the magnet to the other Magnetic – production of a magnetic field by an electric current Electric current flows through a coil of wire a magnetic field is produced similar to a bar magnet. Electromagnetism – magnet that is made by passing an electric current through a coil of wire wrapped around an iron core. Electromagnet Usefulness of electromagnets: Temporary – they can be turned off and on Strength of magnet can be increased •Increase strength of current •Add more coils •Increase size of core Motor – transforms electrical energy into mechanical Generator – transforms mechanical energy into electrical Electric