matter: anything that has mass and takes up space matter: anything that has mass and takes up space...
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Matter: anything that has mass and Matter: anything that has mass and takes up spacetakes up space Mass – the amount of matter in somethingMass – the amount of matter in something Volume – the amount of space something Volume – the amount of space something
occupiesoccupies
Which of the following is matter?Which of the following is matter? A car?A car? A box?A box? You?You?
Reviewing MATTERReviewing MATTER
What is a property?What is a property?
PropertyProperty: a : a characteristic characteristic of a substance of a substance that can be that can be observedobserved
Physical Property Physical Property
Physical property: a property that can be observed without changing the identity of the substance.
Examples:
• luster
• malleability: the ability to be hammered into a thin sheet
• ductility: the ability to be stretched into a wire
• melting point
• boiling point
• density
• solubility
• specific heat
EXTENSIVE PROPERTYEXTENSIVE PROPERTY Depends on the Depends on the amountamount of matter. of matter.
Example – Example – Length, mass,Length, mass,
volume, weightvolume, weight
Additional Physical Additional Physical Properties…Properties…
INTENSIVE PROPERTYINTENSIVE PROPERTY
Does Does notnot depend on the amount of depend on the amount of matter.matter.
Example – Color, density, Example – Color, density, hardness, ductility, hardness, ductility,
malleability, odor, malleability, odor,
melting/ boiling pointmelting/ boiling point
Special Physical Special Physical PropertiesProperties
Melting pointMelting point: the : the temperature at which a temperature at which a substance changes from a substance changes from a solid to a liquid at a given solid to a liquid at a given pressure pressure
water = 0water = 0ooCC
Special Physical Special Physical PropertiesProperties
Boiling pointBoiling point: the : the temperature at which a temperature at which a substance changes from a substance changes from a liquid to a gas at a given liquid to a gas at a given pressurepressure
water = 100water = 100ooCC
DensityDensity DensityDensity is the amount of mass per is the amount of mass per
unit of volume.unit of volume. Since density is an Since density is an intensiveintensive
property, it can be used to identify property, it can be used to identify a substance.a substance.
Density Density
The density of water is The density of water is 1.0g/mL1.0g/mL
If a substance has a density If a substance has a density higherhigher than 1 it will than 1 it will sinksink in in water, water, lessless than 1 it will than 1 it will floatfloat in water.in water.
Density CalculationsDensity Calculations
Calculations:Calculations:
Density = Density = mass mass = = g/mL = g/cm3
VolumeVolume
Units are grams/ml or grams/cm3Units are grams/ml or grams/cm3
where mass is measured in grams and where mass is measured in grams and
volume is measured in ml or cm3volume is measured in ml or cm3
Density CalculationsDensity Calculations
A cube has a mass of 2.8 g and occupies a A cube has a mass of 2.8 g and occupies a volume of 3.67 ml. Would this object float or volume of 3.67 ml. Would this object float or sink in water?sink in water?
Mass = 2.8 gMass = 2.8 g Volume = 3.67 mLVolume = 3.67 mL
D = 2.8g/3.67 mL= 0.76 g/mLD = 2.8g/3.67 mL= 0.76 g/mL
This object would float in water because its This object would float in water because its density is less than water (1.0 g/mL).density is less than water (1.0 g/mL).
Chemical PropertiesChemical Properties Chemical propertyChemical property: a property that : a property that
can only be observed by changing can only be observed by changing the identity of the substancethe identity of the substance
Examples:
•Flammability: ability to burn
•Ability to rust
•reactivity with vinegar
PHYSICAL & CHEMICAL PHYSICAL & CHEMICAL CHANGESCHANGES
Changes in matterChanges in matter
Change: the act of altering a Change: the act of altering a substancesubstance
In science, we talk of two types In science, we talk of two types of changes:of changes:
physicalphysical
chemicalchemical
Physical ChangePhysical Change
Physical change: a change that occurs Physical change: a change that occurs that does not change the identity or that does not change the identity or make up of the substancemake up of the substance Melting ice (change in state or phase)Melting ice (change in state or phase) Freezing Kool-aidFreezing Kool-aid Tearing paperTearing paper Boiling water (same as melting)Boiling water (same as melting)
Physical ChangesPhysical Changes
Physical changes Physical changes are changes that are changes that alter the size, alter the size, shape, location or shape, location or physical state of a physical state of a substance but not substance but not its its chemicalchemical state. state.
Here’s An Example…Here’s An Example… A physical change in a substance doesn't A physical change in a substance doesn't
change what the change what the substance is.substance is. cutting paper – cutting paper –
physical change in the shape and size physical change in the shape and size of the paper. of the paper.
It is still It is still paper!!!!!!paper!!!!!!
So What Does That All Mean?So What Does That All Mean? If the substance is still the same If the substance is still the same
substancesubstance after it has been after it has been changed…changed… It’s a Physical Change.It’s a Physical Change. Example… Boiling waterExample… Boiling water Boiling Water becomes Boiling Water becomes
Water vapor Water vapor
Water = waterWater = water
What Other Kinds of What Other Kinds of Changes Are Physical?Changes Are Physical?
CuttingCutting TearingTearing ShreddingShredding ShrinkingShrinking EnlargingEnlarging
Change in Change in Phase Phase
RelocatingRelocating DissolvingDissolving RotatingRotating Molding Molding
(shaping)(shaping)
Under certain conditions, a substance can change from any one state of matter another. Changes of state are physical changes.
Wood cut down into logs is a physical change
Chemical ChangesChemical Changes
Chemical change: a change that Chemical change: a change that occurs causing the identity of the occurs causing the identity of the substance to changesubstance to change BurningBurning Digesting food Digesting food Reacting with other substancesReacting with other substances
A chemical change is also called a A chemical change is also called a chemical reactionchemical reaction
Chemical ChangesChemical Changes
Chemical changes Chemical changes are changes that are changes that alter the alter the chemical chemical make up of the make up of the substance being substance being changed.changed.
Chemical ChangesChemical Changes
If you end up with a chemical If you end up with a chemical or chemicals that you did not or chemicals that you did not start with. . . start with. . .
It is a chemical change!!!!!!!It is a chemical change!!!!!!!
Chemical ChangesChemical Changes A new substance is formed A new substance is formed
with new and different with new and different properties.properties.
A chemical change is not A chemical change is not easily reversed. easily reversed.
Signs That a Chemical Signs That a Chemical Change has occurredChange has occurred
Creation of a gas (bubbles)Creation of a gas (bubbles) Creation or loss of heatCreation or loss of heat FireFire RottingRotting Breaking down (decomposition)Breaking down (decomposition) Precipitation (Sour milk clumps)Precipitation (Sour milk clumps) CookingCooking Rusting (oxidation)Rusting (oxidation)
The strike of a match is a chemical change due to the reaction of the chemicals with oxygen.
Burning woods turns to charcoal and ashes. This is a chemical change.
Is it Physical or Is it Physical or Chemical?Chemical?
ChangeChange PhysicalPhysical ChemicalChemical
Melting cheeseMelting cheese
Burning woodBurning wood
Milk souringMilk souring
Folding up paperFolding up paper
Bicycle rustingBicycle rusting
Start physical changes challenge PowerpointStart physical changes challenge Powerpoint
Chemical Reactions are…Chemical Reactions are… When one or more substances are changed When one or more substances are changed
into new substances.into new substances. ReactantsReactants- the stuff you start with- the stuff you start with ProductsProducts- what you make- what you make The products will have NEW The products will have NEW
PROPERTIES different from the reactants PROPERTIES different from the reactants you started withyou started with
Arrow points from the reactants Arrow points from the reactants toto the the new productsnew products
Plants make chlorophyll in the plants leaves.
The color changes in autumn leaves are due, in part, to the ending of a chemical reaction. The plants stop making chlorophyll while existing chlorophyll is breaking down. The brilliant colors of fall foliage result when green chlorophyll in leaves breaks down. The colors of other substances in the leaves become visible.
The copper-covered Statue of Liberty has stood in upper New York Bay for more than a 100 years. The green color of the Statue of Liberty comes from a change to the statues copper metal covering. These changes are a result from chemical reactions.
Conservation of Mass Conservation of Mass During any chemical reaction, the mass of During any chemical reaction, the mass of
the products is always equal to the mass the products is always equal to the mass of the reactants.of the reactants.
All the massAll the mass can be accounted for: can be accounted for: Burning of wood results in products that Burning of wood results in products that
appear to have less mass as ashes; where is appear to have less mass as ashes; where is the rest?the rest?
Law of conservation of massLaw of conservation of mass
Matter changes whenever energy is added or taken away. In every physical and chemical change, the total amount of energy stays the same. This principle is called the Law of Conservation of Energy.