Chapter 2

Introduction to matter8th Grade Science

Properties of Matter

• ____________is anything that takes up space and has mass.

• _____________is the study of the properties of matter and how matter changes

• The ____________ and changes in matter depend on its makeup or composition

• A __________is a single type of matter that is pure (has a specific set of properties)Examples of pure substances:_________________

substance

Chemistry

properties

Matter

Sugar and salt

Properties of Matter

• Every form of matter has two kinds of properties:– ________ properties – characteristics of a pure

substance that can be observed without changing it into another substance. A physical property of water is that it freezes at 0• Solid, liquid, gas are physical properties of matter

– _________ properties – a characteristic of a pure substance that describes its ability to change into different substances. To observe the chemical properties you must try to change it to another substance. Flammability, reactivity,

Physical

Chemical

Examples of physical and chemical properties

• Physical– Freezing– Bumpy texture and color are physical properties– Flexibility – bend into shapes without breaking

Chemical- Iron forms rust when it is combined with oxygen in air- Silver will react with sulfur in air to form tarnish- Property of gold is that it does not react easily with

oxygen and sulfur

Elements

• An ______________is a pure substance that cannot be broken down into any other substance by chemical or physical means.– Simplest substances– Identified by specific __________and

______________properties– Examples: ______________(foil) and

___________(pennies)– Elements can be in solid, liquid or gas form– Elements are represented by either one or two-letter

symbols such as ___(aluminum) or __ (carbon)

element

PhysicalChemical

AluminumCopper

Al C

Particles of Elements

• An ____________is the basic particle from which elements are made– Different elements have different properties

because their _________ are different.– All matter is made up of _____________– Atoms have the ability to combine with

___________.– When atoms combine they form a ____________-

a force of attraction between two atoms.

Atom

atoms

atoms

other atoms

Chemical bond

When Atoms Combine…..

• Atoms combine to form larger particles called ___________.

• Molecules are groups of two or more atoms held together by ________________.

• Water – two atoms of _________ chemically bonded to one atom of _________.

• Two atoms of the same element can combine to form a _______.

molecules

Chemical bonds

Hydrogen (H)Oxygen (O)

molecule

Compounds

• All ______is made up of _______• Most _________in nature are found combined with

other _________.• A pure substance made up of two or more elements

chemically combined in a set ratio is called a ___________

• A compound is represented by ____________• The chemical formula show the elements that are

found in the compound and the ratio of the ______ Ex. Carbon dioxide- ratio 1:2

matter elementselements

elements

compoundChemical formula

atoms

Chemical Formulas

• If a different ratio of carbon to oxygen was present – it would be a different___________.

• When elements are chemically combined, they form compounds having ________that are different from those of the uncombined elements.

• Examples: – silver sulfide– Table sugar

compound

properties

Mixtures

• Elements and compounds are _____________• A __________ is made up of two or more

substances – the substances can be elements, compounds, or both.

• Mixtures differ from compounds in two ways:– Each substance in a mixture keeps

its____________________– Parts of a mixture are not combined in a_________.Example: soil mixture, sand, clay, water, etc. Not all soil

samples are the same

Pure substancesmixture

Individual propertiesSet ratio

Types of Mixtures

• ________________ - a mixture where you can see the individual parts. Example: salad

• ________________ - substances are evenly mixed so that the individual substances cannot be seen. Example: lemonade– ______________ is an example of a homogeneous

mixture.• Does not have to be a liquid• Air is an example of a solution-gas solution• Brass is an example of a solid solution

heterogeneous

homogeneous

solution

Separating Mixtures

• A _________ is difficult to separate into its elements

• A ________ is not difficult to separate into its components because each component keeps its own _____________.

• Methods of separating a mixture:– Magnetic attraction– Filtering the mixture– Distilling a liquid solution– evaporation

Compound

Mixture

properties

Measuring Matter

___________ is a measure of the force of gravity on an object.- on Earth, all objects are attracted towards the center of the earth based on the force of the earth’s gravity. On the moon, you would weigh one sixth of your total weight on earth.

____________ is the measurement of the amount of matter in an object-the mass of your body does not change on the moon

* Weight can change with location. Mass does not change with location even when the force of gravity on the object changes.

Weight

Mass

Units of Mass, Volume, and Density

• ______________________is the measurement system used by scientists to measure properties of matter.

• ____________is the amount of space that matter occupies. Formula: length x width x height

• ____________relates to the mass of a material in a given volume. Formula: mass ÷ volume

International System of Units (SI)

Volume

Density

Sinking or Floating

• Objects with densities ________than water will sink.

• Objects with densities _________than that of water will float.

• Density is a ___________property of a substance.

• Brainpower – why does the oil in a bottle of salad dressing rise to the top of the bottle?

greater

less

physical

Section 2 Assessment

• Question 1a and 1b• Question 2a, 2b, and 2c• Question 4 Calculating Density Practice

Changes in Matter

• _______________ change is any change that alters the form or appearance of matter but does not make any substance in the matter into a different substance.– Example: sand that is used in an art sculpture is

still sand just in a different form– When matter changes state from a solid, liquid, or

gas – a _____________change has occurred.

Physical

physical

Examples of Physical Changes

• _____________• _____________• ____________• _____________• ____________• _____________• _____________

Dissolving

Bending

Crushing

Breaking

Chopping

Filtration

Distillation

Chemical Change

• _____________ change is a change in matter that produces one or more new substances- a substance is transformed into a different substance.- the new substances have ___________ that are different from the original substances- Examples of chemical changes: burning natural gas, rust, tarnish, and breaking down water into its elements

Chemical

properties

Examples of Chemical ChangeChemical Change Description Example

Combustion A rapid reaction between fuel and oxygen that results in fire

Gas, oil, or coal burning in a furnace

Electrolysis Use of electricity to break a compound into its elements or simpler compounds

Breaking down water into oxygen and hydrogen

Oxidation Slow combination of a substance with oxygen

Rusting of an iron fence

Tarnishing Slow combination of a bright metal with sulfur or another substance, producing a dark coating on the metal

Tarnishing of brass

Law of Conservation of Mass

• __________________in the 1770’s made accurate measurements of mass both before and after a chemical change.

• His data showed that mass was neither lost nor gained as a result of the change

• _____________________ - matter is not created or destroyed– Since mass measures the amount of _________, this

law is sometimes referred to as the __________________________

Antoine Lavoisier

Law of Conservation of Mass

matter

Law of Conservation of Matter

Conserving Matter

Chemical Reaction in Methane

• No mass is lost during the combustion of methane gas

• During a chemical change, ________ are not lost or gained – they are simply rearranged.

• For every molecule of ________ that burns, two molecules of _________ are used.

• The ______are rearranged in the reaction, but they do not disappear.

atoms

methane

oxygen

atoms

Thermal Energy

• ____________is the ability to do work or cause change• Chemical or physical changes in _________ includes a

change in __________.• ______________ is a measure of the average energy or

random motion of particles of matter• ______________ is the total energy of the particles in an

object• __________________is related to the amount of

__________________ an object has.• ___________________ always flows from warmer matter

to cooler matter

Energymatter

EnergyTemperature

Thermal Energy

TemperatureThermal EnergyThermal Energy

Thermal Energy and Changes in Matter

• When matter changes thermal energy is either __________ or ____________

• ______________ change is a change in which energy is taken in

• _______________ change occurs when energy is released or given off

• ___________ is a chemical change that releases energy in the form of heat and light

absorbed released

Endothermic

Exothermic

Combustion

Forms of Energy

• Energy comes in many forms:– Kinetic– Potential– Chemical– Electromagnetic– Electrical– Thermal

Kinetic Energy

• Kinetic Energy – the energy of matter in _________.– The smallest particles of matter have __________

energy because they are in constant, random motion.

– The kinetic energy of particles contributes to the __________ energy of a substance

– A rolling ball has kinetic energy because the particles that make up the ball are in motion.

motion

kinetic

thermal

Potential Energy

• Potential energy is energy that is ________ as a result of the objects _________.– When a diver climbs to the top of a diving board

his/her potential energy ___________. – When you stretch a rubber band, you are giving

the rubber band ____________ energy because it has the ability to snap back and do work.

– Other types of potential energy: a book on top of your desk – it has the potential to fall off

position

stored

increases

potential

Chemical Energy

• Chemical energy is the internal energy stored in the _______________ between atoms.

• Chemical energy is also a form of _______ energy because the energy is stored.

• When a chemical change occurs, the chemical bonds are _______ and new bonds are formed.

Chemical bonds

potential

broken

Electromagnetic energy

• Electromagnetic energy is a form of energy that travels through _________ as ________.

• Examples: radio waves, infrared rays, the waves that heat food in the microwave, ultraviolet waves, and x-rays.

• _________ is an example of electromagnetic energy.

• __________ changes give off electromagnetic energy such as light from a wood fire.

space waves

Visible light

Chemical

Electrical Energy

• Electrical Energy is the energy of ________charged particles moving from one place to another.

• ___________ move from one atom to another in many ____________ reactions.

• _____________ are two metal strips that are used to conduct electrical energy when connected to an electrical energy source such as a ____________.

electrically

electronsChemical

Electrodes

battery

Transformed Energy

• Burning of fuel is a ________ change that transforms ____________ energy and releases it as ____________ energy and ____________ energy.

• When you exercise, ___________ energy from food is transformed into __________ energy of your moving muscles.

• Photosynthesis – plants transform ____________ energy into _________ energy as they make molecules of sugar.

chemicalChemical

thermal electromagnetic

chemicalkinetic

electromagneticchemical

Section 2-4 Assessment

• 1a, 1b, 2a, 2b, 2c