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.