Exploring the Nature Exploring the Nature of Matterof Matter

Particle Theory of MatterParticle Theory of Matter

►All matter is made up of extremely All matter is made up of extremely tiny particles.tiny particles.

►Each pure substance has its own kind Each pure substance has its own kind of particle, different from the of particle, different from the particles of other pure substances.particles of other pure substances.

►Particles attract each other.Particles attract each other.►Particles are always moving.Particles are always moving.►Particles at a higher temperature Particles at a higher temperature

move faster on average than move faster on average than particles at a lower temperature.particles at a lower temperature.

Scientific ModelsScientific Models► Scientific models help scientists to picture Scientific models help scientists to picture

processes in nature that are difficult to processes in nature that are difficult to directly see.directly see.

► The Particle Theory of Matter is an The Particle Theory of Matter is an example of scientific modelexample of scientific model

► The first two points of the PTM allow us to The first two points of the PTM allow us to understand how particles make up understand how particles make up substances.substances.

► The last three points explain properties The last three points explain properties like how particles stay together and how like how particles stay together and how they behave when temperature changes.they behave when temperature changes.

States of Matter and the PTMStates of Matter and the PTM

►Solids – particles do not have enough Solids – particles do not have enough energy to move from place to placeenergy to move from place to place

►Liquids – particles have enough energy Liquids – particles have enough energy to break some of the attractive forces to break some of the attractive forces but not all of them.but not all of them.

►Gases – particles have enough energy Gases – particles have enough energy to break all of the attractive forcesto break all of the attractive forces

Change of StateChange of State►Solid to liquid (melting) – particles gain Solid to liquid (melting) – particles gain

energyenergy►Liquid to gas (evaporation) – particles Liquid to gas (evaporation) – particles

gain energygain energy►Gas to liquid (condensation) – particles Gas to liquid (condensation) – particles

lose energylose energy►Liquid to solid (solidification) – particles Liquid to solid (solidification) – particles

lose energylose energy►Gas to solid (deposition) – no liquid Gas to solid (deposition) – no liquid

phasephase►Solid to gas (sublimation) – no liquid Solid to gas (sublimation) – no liquid

phasephase

Classifying MatterClassifying Matter

►Matter can be classified by its state Matter can be classified by its state (solid, liquid, or gas)(solid, liquid, or gas)

►Matter can also be classified according Matter can also be classified according to one of its properties (heterogeneous to one of its properties (heterogeneous or homogeneous substance)or homogeneous substance)

►Heterogeneous – does not have a Heterogeneous – does not have a uniform composition (salad dressing)uniform composition (salad dressing)

►Homogeneous – consists of a uniform Homogeneous – consists of a uniform composition (salt, water, salt water, composition (salt, water, salt water, gold, etc.)gold, etc.)

Classifying MatterClassifying Matter

►Matter can also be classified based on Matter can also be classified based on its composition: a mixture or a pure its composition: a mixture or a pure substancesubstance

► Mixture – a substance composed of Mixture – a substance composed of two or more particlestwo or more particles

►Pure substance – a substance Pure substance – a substance composed of one unique particle composed of one unique particle

Chemical and Physical Chemical and Physical ChangesChanges

►A A chemical changechemical change occurs when: occurs when: a change in which something new is formed.a change in which something new is formed. The starting materials change into an The starting materials change into an

entirely different substance or substances. entirely different substance or substances. This new substance has a different chemical This new substance has a different chemical composition than the starting materials. composition than the starting materials.

►Examples of chemical changes would be Examples of chemical changes would be the reaction of iron with air (rusting} or the reaction of iron with air (rusting} or the reaction of a metal and acid. the reaction of a metal and acid.

►Certain observations will indicate that a Certain observations will indicate that a chemical change has occurred. These chemical change has occurred. These are:are: The reaction produced a change in The reaction produced a change in

temperature. temperature. Formation of gas bubbles. Formation of gas bubbles. Formation of a solid (precipitate). Formation of a solid (precipitate). A change in color. A change in color. Formation of a different odour. Formation of a different odour. Starting material is used up.Starting material is used up. A material with new properties is formed.A material with new properties is formed.

► If two or more of the above occur then a If two or more of the above occur then a chemical change has probably taken chemical change has probably taken place.place.

►Physical changePhysical change is a change in which is a change in which the substance changes form but keeps the substance changes form but keeps its same chemical composition. its same chemical composition.

►Examples:Examples:►Changes of state are considered to be Changes of state are considered to be

physical changes. Liquid water and ice physical changes. Liquid water and ice (frozen water) are both the same (frozen water) are both the same substance, water. substance, water.

► If you fold a piece of paper it is a If you fold a piece of paper it is a physical change. You have changed physical change. You have changed the form of the paper but you have not the form of the paper but you have not changed the fact that it is paper. changed the fact that it is paper.

► If you heat an iron bar until it glows red hot, it If you heat an iron bar until it glows red hot, it is still chemically the same iron. The iron has is still chemically the same iron. The iron has not changed into something else. not changed into something else.

► If you dissolve salt in water you have not If you dissolve salt in water you have not changed the materials chemically. You still changed the materials chemically. You still have salt and you still have water. This can be have salt and you still have water. This can be shown if you choose to separate the mixture shown if you choose to separate the mixture by distillation or the simple evaporation of the by distillation or the simple evaporation of the water. The salt would be the residue and the water. The salt would be the residue and the water would be the distillate. water would be the distillate.

Physical PropertiesPhysical Properties

►Physical properties are those that can Physical properties are those that can be observed without changing the be observed without changing the identity of the substance. The general identity of the substance. The general properties of matter such as color, properties of matter such as color, density, hardness, are examples of density, hardness, are examples of physical properties. physical properties.

►Can you think of any physical Can you think of any physical properties?properties?

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Physical PropertiesPhysical Properties

► ColourColour► TasteTaste► SmellSmell► State of matterState of matter► MalleabilityMalleability► DuctilityDuctility► Melting pointMelting point► Boiling pointBoiling point► DensityDensity► SolubilitySolubility► ViscosityViscosity

Physical PropertiesPhysical Properties

►The previous list can be broken into The previous list can be broken into two types of physical properties: two types of physical properties: qualitative and quantitative.qualitative and quantitative.

►Qualitative Physical Properties: a Qualitative Physical Properties: a characteristic that can be described characteristic that can be described but not measured.but not measured.

►Quantitative Physical Properties: a Quantitative Physical Properties: a characteristic that can be measured characteristic that can be measured numerically.numerically.

Chemical PropertiesChemical Properties

►A characteristic of a substance that A characteristic of a substance that describes its ability to react chemically describes its ability to react chemically with another substance.with another substance.

►Can you think of any chemical Can you think of any chemical properties?properties? CombustibilityCombustibility Reacts with airReacts with air Reacts with waterReacts with water Reacts with oxygenReacts with oxygen Reacts with….Reacts with….