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Mrs. McCarthy’s MCAS Review Physical Sciences • 8th Grade Curriculum –Properties of Matter –The Atom –Elements, Compounds, and Mixtures –Motion –Forms of Energy & Heat • • • • • • • Particle Motion & Phase Changes (15) Mass vs. Weight (1) Volume vs. Mass; Density (2) Measuring Tools (3) Conservation of Mass (4) Melting Point & Boiling Point (9) Physical & Chemical Changes (10) Solid • Has a definite shape and a definite volume • Particles are held tightly in place and vibrate in place Looks Like Liquid • Have a definite volume and no definite shape • Take the shape of a container • Can Pour • Particles slide past one another Looks Like Gas • Have NO Definite Shape or Volume • Fill their containers • Particles spread out and move independently Looks Like Plasma • • • • Very high in energy Plasma has no definite shape or volume Particles are broken Plasma is the most common phase of matter in the universe • Examples: Auroras, lightning, fire, neon lights Charles’ Law • The volume of a gas increases as its temperature increases • For Example: – A balloon expands and pops when it is heated. – A balloon contracts and gets smaller when it is cooled. Boyle’s Law • The volume of gas increases as the pressure decreases • Example: Piston – Lifting the Plunger Decreases the Pressure – Pushing the Plunger Increases the Pressure States of Matter Matter changes phases due to a change in the heat energy of an object’s particles. Solid Phases Changes Add Energy/Heat Liquid Gas Lose Energy/Heat ← Measurement • Mass • Weight • Volume • Temperature Mass • The amount of matter in an object • Doesn’t change with gravity • Measured with a triple-beam balance • SI unit of grams Inertia • A resistance to a change in motion • The more mass an object has, the more inertia it has • Example: Grocery Carts & Cars Weight • The amount of gravitational pull on an object • Changes with gravity • Measured in Newtons Volume • The amount of space an object takes-up • Can be measured with a ruler using the formula: Volume = length * width * height OR • Volume can be measured with water and a graduated cylinder using displacement • Solid SI Unit of cm³ • Liquid SI Unit of mL Density • The amount of mass in a given volume • Measured with the Formula: Density = Mass / Volume Mass ______________ Density * Volume * Labeled in g/cm³ Density Stackers • Many liquid mixtures will stack up into layers by their densities – More dense materials will be below less dense materials – Example: Salad Dressing Characteristic Properties • Describe substances based upon their characteristics • Example: Physical Properties Chemical Properties Physical Properties • Physically describe an object based upon observable and measurable observations Examples: COLOR Mass Volume Weight Boiling Density Malleability Temperature Ductility Solubility Texture State Melting Melting Point & Boiling Point • Each Substance has its own Melting & Boiling Points that are always the same temperature regardless of the size Particle Motion & Temperature Increases • Melting- the change from a solid to a liquid • Adding energy • Boiling- the change from a liquid to a gas • Adding Energy Melting & Boiling Points • Melting Point: All Water Melts at 0˚C • Boiling Point: All water boils at 100˚C Physical Changes • A change in a substance that affects one or more physical properties of a substance • The substance does not change • Examples: Cutting Hair Crushing a Can Sanding Wood Broken Glass Melting Butter Freezing Water Dissolving Salt Bending Metal Chemical Properties • Describe substances based upon their ability to change into a new substance with different properties • Chemical properties are not easily observed with your senses and often need to be tested • Examples: Reactivity: Tarnishing, Rusting, Flammability Chemical Changes • When substances change into new substances with different properties • Examples: Reactivity Gas Formation & Bubbles Burning Cooking Conservation of Mass • Mass cannot be created or destroyed • Even during a chemical reaction, the mass will remain the same. • Example- Lab with: Vinegar, Baking Soda, Baggies, Film Canister, & T.B.B. Before After • There are more than 100 elements on the periodic table that make up ALL things (5) • Atoms of Elements vs. Molecules of Compound (6) • Examples of Elements and Compounds (7) • Mixtures vs. Pure Substances (8) Atomic Theory • Democritus- Proposes the Atom 440 B.C. • Dalton- Atoms are the Smallest Particle • Thomson- “Plum Pudding” with Electrons • Rutherford- Gold Foil → Atom’s Nucleus • Bohr- Electrons Travel in Energy Paths • Schrödinger & Heisenberg- Electron Clouds Atom • The Smallest Unit of an Element • Everything is made of Atoms Energy Levels Nucleus with Protons and Neutrons Electrons Protons • • • • • Charge: Positive Mass:1 amu Location: Nucleus Proton count determines the element Protons = atomic number Neutrons Charge: none Mass: 1 amu Location: Nucleus *To find the neutrons: atomic mass – atomic number Electrons • Charge: Negative • Mass: Almost Zero • Location: Electron Clouds • Balanced Atoms: Protons = Electrons Periodic Table • • • • • Organized Data of Elements Organized by Atomic Number Over 100 Elements Contains Many Patterns Element Cube: 2 Atomic Number He Chemical Symbol Helium Element Name 4.0 Atomic Mass Pure Substances • A substance with only one type of particle • Examples: Elements & Compounds • Pure Substances Cannot be Broken Down and Retain their Properties Elements Elements Metals Shiny, Strong Conductors, Malleable, Ductile Left of zigzag line Nonmetals Dull, Poor Conductors, Brittle Metalloids Semiconductors, Have Properties of Metals & Nonmetals Right of zigzag line Border the zigzag line Mixtures • A combination of two or more substances that are not chemically combined. • A mixture is easily separated by physical means • A mixture is NOT a pure substance. Separating Mixtures Techniques: - Magnet: uses a magnet - Filter: uses a sifter - Centrifuge: uses spinning (densities) - Solutions: uses dissolving - Distillation: uses boiling point Chemical Reactions • The process where one or more substances changes to become one or more different substances. • LAW OF CONSERVATION OF MASS – Mass is never gained or lost in a chemical reaction Clues to Chemical Reactions • Gas Formation • Solid Formation • Color Change • Energy Change Chemical Formulas & Equations • A chemical formula uses symbols and numbers to represent a compound • Chemical Equations uses formulas and symbols to show a chemical reaction – Chemical Equations MUST be Balanced and follow the Law of Conservation of Mass Example: C + O2 CO2 • Motion is described by Position, Direction, & Speed • Graphs of Distance vs. Time (S= D/T) Motion A change in an object’s position relative to reference point(s) during a specific length of time Distance Speed * Time Velocity Speed an object travels in a given direction The unit label is ALWAYS a: Distance/Time & Direction Word Example: 60 miles/hour West Example Direction Words: North, South, East, West, Left, Right, Up, Down Force •A push or a pull •Exerted on one object by another object •Can affect an object’s speed or direction Unbalanced forces If the net force on an object is NOT ZERO. The resulting effect is the object changes its motion. Balanced forces If the net force on an object is ZERO the resulting effect is the object has NO change in its motion. Friction •Resists Motion Between 2 Objects •Dependent on Texture of Surfaces •4 major types: Rolling, Sliding, Static, Fluid GRAVITY Gravity is a force of attraction • Exists between any two objects •The force is dependent upon The size of the objects and the distance they are from one another Law of Universal Gravitation •The force of Gravity is dependent upon the size of the object and the distance they are from one another. Gravitation force increases • as masses increase • as the distance decreases •Bigger & Closer Gravitation force decreases • as masses decrease • as the distance increases •Smaller & Farther •Weight is a measurement of a planet’s gravitational pull on the mass of an object. •Therefore, weight is different on different planets and other celestial Mass vs. Weight • Measured with a triple beam balance. • Measured with a Newton spring scale. • Acceleration is the rate at which velocity changes. • Gravity causes all objects, regardless of size, to fall at the same acceleration • On Earth, all objects fall at a rate of 9.8 m/s/s Projectile Motion Occurs when an object has two forces acting on it: gravity & a push-horizontal- force. The result is a curved path • Potential Energy vs. Kinetic Energy and Energy Changes (13) • Heat is Energy that causes temperature changes (14) • Heat causes Phase Changes (15) • Heat moves from warmer objects to cooler objects (16) Different forms of Energy Heat/Thermal Nuclear Light Chemical Elastic Sound Electromagnetic •Energy •the ability to do work •Work occurs when an object moves in the direction of the applied force Energy, like work, is measured in joules (J). Energy exists in many different forms and can change between them: Energy conversion Energy transformation Types of Energy • Potential Energy: –Stored Energy • Kinetic Energy: –Energy of Motion Energy Changes • Energy can be Transferred between Potential Energy and Kinetic Energy Law of Conservation of Energy Energy can not be created or destroyed. It can change forms. Heat Heat is a form of thermal energy. Heat is Energy that causes temperature changes. Each Substance has unique Melting and Boiling points. Heat Changes Particle Motion and Causes Phase Changes. Heat Moves from Warm Objects to Cooler Objects. Temperature • Temperature is a Measurement of Heat • Temperature is Measured with a Thermometer • Temperature Scales: – Celsius (˚C) – Fahrenheit (˚F) – Kelvin (k) Melting Point & Boiling Point • Each Substance has its own Melting & Boiling Points that are always the same temperature regardless of the size Particle Motion & Temperature Increases • Melting- the change from a solid to a liquid • Adding energy • Boiling- the change from a liquid to a gas • Adding Energy Melting & Boiling Points • Melting Point: All Water Melts at 0˚C • Boiling Point: All water boils at 100˚C States of Matter Matter changes phases due to a change in the heat energy of an object’s particles. Solid Phases Changes Add Energy/Heat Liquid Gas Lose Energy/Heat ← Heat Transfer • Heat moves in predictable ways from warm objects to cooler objects Heat energy moves in three ways: Conduction Convection Radiation Conduction :occurs when energy is passed directly from one item to another Convection Convection : movement of gases or liquids from a cooler spot to a warmer spot. Examples- Air Masses, Earth’s Mantle; Ocean Convection : movement of FLUIDS (GAS OR LIQUID) from a cooler spot to a warmer spot. WIND EARTH BOILING Radiation :The sun's rays travel in straight lines called heat rays. When sunlight hits the earth, its radiation is absorbed or reflected. Darker surfaces absorb more of the radiation and lighter surfaces reflect the radiation.