Mrs. McCarthy’s MCAS Review Physical Sciences 8 th Grade Curriculum –Properties of Matter –The...
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Transcript of Mrs. McCarthy’s MCAS Review Physical Sciences 8 th Grade Curriculum –Properties of Matter –The...
Mrs. McCarthy’s MCAS ReviewPhysical 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
PhasesChanges
Solid Liquid Gas
Matter changes phases due to a change in the heat energy of an object’s particles.
Add Energy/Heat
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 Density Solubility
Mass Malleability Texture Volume Temperature State Weight Ductility Melting
Boiling
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
Electrons
Energy
LevelsNucleus
with Protons
and Neutrons
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
HeHelium
4.0
Atomic Number
Chemical Symbol
Element Name
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
MetalsShiny, Strong Conductors,
Malleable, Ductile
NonmetalsDull, Poor
Conductors, Brittle
MetalloidsSemiconductors,
Have Properties of Metals & Nonmetals
Left of zigzag line 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 MixturesTechniques:
- 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 MassExample: C + O2 CO2
• Motion is described by Position, Direction, & Speed
• Graphs of Distance vs. Time (S= D/T)
A change in an object’s position relative to reference point(s)
during a specific length of time
Motion
Distance
Speed * Time
Speed an object travels in a given direction
The unit label is ALWAYS a: Distance/Time The unit label is ALWAYS a: Distance/Time & Direction Word& Direction Word
Example: 60 miles/hour WestExample: 60 miles/hour West
Velocity
Example Direction Words: North, South, East, West, Left, Right, Up, Down
ForceForce
• ExertedExerted on one object on one object
by by anotheranother objectobject
•A pushpush or a or a pullpull
•Can affect an object’s Can affect an object’s speed or directionspeed or direction
Unbalanced forcesUnbalanced forces
If the net force on an object is If the net force on an object is NOT ZERO.NOT ZERO.
The resulting effect is the The resulting effect is the object changes its motion.object changes its motion.
Balanced forcesBalanced forces
If the net force on an object If the net force on an object is is ZEROZERO
the resulting effect is the the resulting effect is the object has object has
NO changeNO change in its motion. in its motion.
Friction Friction
•Resists Motion Between 2 Resists Motion Between 2 ObjectsObjects
•Dependent on Texture of Dependent on Texture of SurfacesSurfaces
•4 major types: Rolling, Sliding, 4 major types: Rolling, Sliding, Static, FluidStatic, Fluid
GRAVITYGRAVITYGravity is a force of attractionGravity is a force of attraction
• Exists between any two objectsExists between any two objects•The force is The force is dependent upon dependent upon The size of the The size of the objects and the objects and the distance they distance they are from one are from one anotheranother
•The force of Gravity is The force of Gravity is dependent upon the size of the dependent upon the size of the object and the distance they object and the distance they are from one another.are from one another.
Law of Universal GravitationLaw of Universal Gravitation
Gravitation force Gravitation force increasesincreases• as masses increaseas masses increase• as the distance decreasesas the distance decreases•Bigger & CloserBigger & Closer
Gravitation force Gravitation force decreasesdecreases• as masses decreaseas masses decrease• as the distance increasesas the distance increases•Smaller & FartherSmaller & Farther
•WeightWeight is a measurement of a planet’s gravitational pull on the mass of an object.
•Therefore, weight is Therefore, weight is different on different different on different
planets and planets and other other celestial celestial bodies.bodies.
• Measured with a triple beam balance.
• Measured with a Newton spring scale.
Mass vs. Weight
• 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
Occurs when an object has two forces acting on it:
gravity & a push-horizontal- force.
Projectile Motion
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)
Nuclear
Different forms of Energy
Light
Sound
Elastic
Heat/Thermal
Electromagnetic
Chemical
•Energy
•Work occurs when an object moves in the direction of the applied force
•the ability to do work
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.
HeatHeat 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
PhasesChanges
Solid Liquid Gas
Matter changes phases due to a change in the heat energy of an object’s particles.
Add Energy/Heat
Lose Energy/Heat ←
Heat Transfer
• Heat moves in predictable ways from warm objects to cooler objects
Heat energy Heat energy movesmoves in three ways in three ways: :
Conduction Conduction Convection Convection RadiationRadiation
Conduction :occurs Conduction :occurs when energy is when energy is passed directly from passed directly from one item to anotherone item to another
ConvectionConvection : movement of
gases or liquids from a cooler spot to a warmer spot.
Examples- Air Masses, Earth’s Mantle; Ocean
ConvectionConvection : movement of FLUIDS (GAS OR LIQUID)
from a coolercooler spot to a warmerwarmer spot.
BOILINGBOILING
WINDWIND
EARTH
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.