ChemistryChemistry

1.D Defining 1.D Defining ChemistryChemistry

What is Chemistry?What is Chemistry?

Chemistry is the study of the Chemistry is the study of the composition, structure, and composition, structure, and properties of matter, the processes properties of matter, the processes that matter undergoes, and the that matter undergoes, and the energy changes that accompany energy changes that accompany these processes.these processes.

Matter and Its PropertiesMatter and Its Properties

Everything around you is made up of Everything around you is made up of matter, but what exactly is matter?matter, but what exactly is matter?

Matter is defined as anything that has Matter is defined as anything that has mass and takes up space. mass and takes up space.

Mass = the measure of the amount of Mass = the measure of the amount of mattermatter

Volume = the amount of three Volume = the amount of three dimensional space an object occupies.dimensional space an object occupies.

Basic Building Blocks of Basic Building Blocks of MatterMatter

Matter comes in many forms.Matter comes in many forms.

But the fundamental building blocks But the fundamental building blocks of all matter are atoms.of all matter are atoms.

An atom is the smallest unit of an An atom is the smallest unit of an element that maintains the identity element that maintains the identity of that element. of that element.

An element is a pure substance that An element is a pure substance that cannot be broken down into simpler, cannot be broken down into simpler, stable substances and is made of stable substances and is made of only one type of atom. only one type of atom.

Is water an element?Is water an element?

A compound is a substance that can be A compound is a substance that can be broken down into simple stable broken down into simple stable substances. Each compound is made substances. Each compound is made from atoms of two or more elements from atoms of two or more elements that are chemically bonded. that are chemically bonded.

Water = HWater = H22OO Molecule is the smallest unit of an Molecule is the smallest unit of an

element or compound that retains all of element or compound that retains all of the properties of that element or the properties of that element or compound. compound.

HH22O is a water molecule while HO is a water molecule while H2424OO1212 is is still water. still water.

Properties and Changes of Properties and Changes of MatterMatter

Every substance, whether it is an element Every substance, whether it is an element or a compound, has characteristic or a compound, has characteristic properties. Most chemical investigations properties. Most chemical investigations are related to or depend on the properties are related to or depend on the properties of substances. of substances.

Many elements are classified as metals. A Many elements are classified as metals. A well known property of metals is that they well known property of metals is that they are conductors. are conductors.

Comparisons of several of these properties Comparisons of several of these properties can help identify what an unknown can help identify what an unknown substance is. substance is.

Intensive and Extensive Intensive and Extensive PropertiesProperties

Extensive properties depend on the Extensive properties depend on the amount of matter that is present. amount of matter that is present. (volume, mass, amount of energy in a (volume, mass, amount of energy in a substance)substance)

Intensive properties do not depend Intensive properties do not depend on the amount of matter present. on the amount of matter present. (boiling point, melting point, density)(boiling point, melting point, density)

Intensive properties are the same for Intensive properties are the same for a given substance regardless of how a given substance regardless of how much of the substance is present. much of the substance is present.

Physical Properties and Physical Physical Properties and Physical ChangesChanges

A physical property is a characteristic A physical property is a characteristic that can be observed or measured that can be observed or measured without changing the identity of the without changing the identity of the substance. substance.

Physical properties describe the Physical properties describe the substance itself. (melting point, boiling substance itself. (melting point, boiling point)point)

Physical change is a change in a Physical change is a change in a substance that does not involve a change substance that does not involve a change in the identity of the substance. (cutting, in the identity of the substance. (cutting, melting, boiling, distilling)melting, boiling, distilling)

Change of StateChange of State

Melting and boiling are part of an Melting and boiling are part of an important class of physical changes important class of physical changes called changes of state. called changes of state.

A change of state is a physical A change of state is a physical change of a substance from one change of a substance from one state to another. state to another.

The three common state of matter The three common state of matter are solid, liquid, and gas. are solid, liquid, and gas.

SolidSolid A solid has a definite volume and a A solid has a definite volume and a

definite shape.definite shape. The particles in a solid are packed The particles in a solid are packed

together in relatively fixed positions. together in relatively fixed positions. The particles are held together by The particles are held together by the strong attractive forces between the strong attractive forces between them, and only vibrate about fixed them, and only vibrate about fixed points. points.

LiquidLiquid A liquid has a definite volume but an A liquid has a definite volume but an

indefinite shape. indefinite shape. The particles in a liquid move more The particles in a liquid move more

rapidly than those in a solid. This rapidly than those in a solid. This causes them to overcome causes them to overcome temporarily the strong attractive temporarily the strong attractive forces between them, allowing the forces between them, allowing the liquid to flow.liquid to flow.

GasGas A gas has neither A gas has neither

definite volume nor definite volume nor definite shape. definite shape.

A given quantity of gas A given quantity of gas will expand to fill any will expand to fill any size container. All size container. All gases are composed of gases are composed of particles that move particles that move very rapidly and at very rapidly and at great distances from great distances from one another compared one another compared with the particles of with the particles of liquid and solids.liquid and solids.

PlasmaPlasma

Plasma is a high-temperature Plasma is a high-temperature physical state of matter in which physical state of matter in which atoms lose most of their electrons. atoms lose most of their electrons. Plasma can be found in fluorescent Plasma can be found in fluorescent bulbs. bulbs.

Change of StateChange of State

Melting is when a solid turns into a Melting is when a solid turns into a liquid.liquid.

Boiling is the change from a liquid to Boiling is the change from a liquid to a gas.a gas.

Freezing is the change from a liquid Freezing is the change from a liquid to a solid. to a solid.

A change of state does not affect the A change of state does not affect the identity of the substance. identity of the substance.

Chemical Properties and Chemical Properties and Chemical ChangeChemical Change

A chemical property relates to a substances A chemical property relates to a substances ability to undergo changes that transform it ability to undergo changes that transform it into different substances. Chemical into different substances. Chemical properties are easiest to see when properties are easiest to see when substances react to form new substances. substances react to form new substances.

The ability of charcoal (carbon) to burn in The ability of charcoal (carbon) to burn in air is a chemical property. air is a chemical property.

Burning charcoal: charcoal (carbon) Burning charcoal: charcoal (carbon) combines with oxygen in the air to become combines with oxygen in the air to become carbon dioxide gas COcarbon dioxide gas CO22

Iron will rust when combined with air. Iron will rust when combined with air.

Chemical Change or Chemical Chemical Change or Chemical ReactionReaction

A change in which one or more A change in which one or more substances are converted into different substances are converted into different substances is called a chemical change or substances is called a chemical change or a chemical reaction. (fermentation) a chemical reaction. (fermentation)

The substances that react in a chemical The substances that react in a chemical change are called the reactants. change are called the reactants.

The substances that are formed by the The substances that are formed by the chemical change are called the products. chemical change are called the products.

Chemical ReactionChemical Reaction

In the case of burning charcoal, In the case of burning charcoal, carbon and oxygen are the reactants carbon and oxygen are the reactants and the carbon dioxide is the product. and the carbon dioxide is the product.

Carbon plus oxygen yields (or forms) Carbon plus oxygen yields (or forms) carbon dioxidecarbon dioxide

carbon + oxygen carbon dioxidecarbon + oxygen carbon dioxide carbon = C oxygen = Ocarbon = C oxygen = O22

C + OC + O22 CO CO22

In a chemical reaction we saw that In a chemical reaction we saw that two elements or compounds came two elements or compounds came together to form a new product. together to form a new product. However, one compound can break However, one compound can break down into two elements in a process down into two elements in a process known as decomposition. known as decomposition.

Water = HWater = H22OO

HH22O HO H22 + O + O Water breaks down to form hydrogen Water breaks down to form hydrogen

and oxygenand oxygen

Chemical changes do not change the Chemical changes do not change the amount of total matter present. amount of total matter present. There is the same amount of matter There is the same amount of matter at the beginning and end of a at the beginning and end of a chemical reaction, therefore the chemical reaction, therefore the mass remains the same. This is the mass remains the same. This is the law of conservation of matter. law of conservation of matter.

Law of Conservation of MassLaw of Conservation of Mass

3C3C66HH12120066 3C 3C66 + 18H + 18H2200 If 120 grams of sugar are broken If 120 grams of sugar are broken

down into 103 grams of water, how down into 103 grams of water, how many grams of carbon are produced?many grams of carbon are produced?

Energy and Changes in Energy and Changes in MatterMatter

When physical or chemical changes When physical or chemical changes occur, energy is always involved. occur, energy is always involved.

The energy can take several different The energy can take several different forms, such as heat or light. forms, such as heat or light.

Sometimes heat provides enough Sometimes heat provides enough energy to cause a chemical change, energy to cause a chemical change, such as boiling water to make such as boiling water to make hydrogen gas and oxygen gas. hydrogen gas and oxygen gas.

Accounting for all the Accounting for all the energy present before energy present before and after a change is and after a change is not a simple process. not a simple process.

However, scientists However, scientists are confident that the are confident that the total amount of energy total amount of energy remains the same. remains the same.

Although energy can Although energy can be absorbed or be absorbed or released in a change, released in a change, it is not destroyed or it is not destroyed or created. It simply created. It simply assumes a different assumes a different form. This is the law of form. This is the law of conservation of conservation of energy.energy.

Endothermic ReactionEndothermic Reaction

An endothermic reaction is a reaction An endothermic reaction is a reaction in which energy is absorbed during in which energy is absorbed during the reaction. the reaction.

A temperature drop is one way to A temperature drop is one way to distinguish an endothermic reaction. distinguish an endothermic reaction.

Exothermic ReactionExothermic Reaction

An exothermic reaction is a reaction An exothermic reaction is a reaction in which energy is released during in which energy is released during the reaction. the reaction.

Many chemical reactions release Many chemical reactions release energy in the form of light, sound, or energy in the form of light, sound, or heat.heat.

Specific HeatSpecific Heat The quantity of energy transferred as heat The quantity of energy transferred as heat

during a temperature change depends on during a temperature change depends on the nature of the material changing the nature of the material changing temperature, the mass of the material temperature, the mass of the material changing temperature, and the size of the changing temperature, and the size of the temperature change. temperature change.

One gram of iron heated to 500One gram of iron heated to 500°C and °C and cooled to 50°C transfers 22.5 J of energy. cooled to 50°C transfers 22.5 J of energy. But one gram of silver transfers 11.8 J of But one gram of silver transfers 11.8 J of energy under the same conditions. energy under the same conditions.

A quantity called specific heat can be used A quantity called specific heat can be used to compare heat absorption capacities for to compare heat absorption capacities for different materials. different materials.

Specific Heat (cSpecific Heat (cpp)) Specific heat is the amount of energy Specific heat is the amount of energy

required to raise the temperature of one required to raise the temperature of one gram of a substance by one degree gram of a substance by one degree Celsius or one kelvin. Celsius or one kelvin.

Specific heat derived unit = J/gK or J/gSpecific heat derived unit = J/gK or J/g°C or °C or cal/g°Ccal/g°C

To find specific heat To find specific heat ccp p = q/(m= q/(mΔΔT)T) q is the energy lost of gainedq is the energy lost of gained m is the mass of the samplem is the mass of the sample ΔΔT represents the difference between the T represents the difference between the

initial and final temperatures. initial and final temperatures. ΔΔT = T(final) T = T(final) – T(initial) *this can cause you to have – T(initial) *this can cause you to have a negative sign and this indicates that you a negative sign and this indicates that you are losing heat or energy*are losing heat or energy*

When finding q in specific When finding q in specific heat..heat..

If you have a If you have a ΔΔT that is negative,T that is negative, when when finding the q (energy) you could end finding the q (energy) you could end up with a negative number. You do not up with a negative number. You do not need to write the negative sign if the need to write the negative sign if the question asks you how much energy is question asks you how much energy is lost or gained. If it just asked for the lost or gained. If it just asked for the change in energy, you must write the change in energy, you must write the negative sign because it is not already negative sign because it is not already understood in the problem. understood in the problem.

For those changes which REQUIRE energy;For those changes which REQUIRE energy; solid + energy --> liquid;     Q is positivesolid + energy --> liquid;     Q is positive liquid + energy --> gas;      Q is positiveliquid + energy --> gas;      Q is positive

You have to ADD energy to melt solid You have to ADD energy to melt solid ice;ice;

You have to ADD energy to vaporize the You have to ADD energy to vaporize the liquid water.liquid water.

for those changes which GIVE OFF for those changes which GIVE OFF energy;energy;

gas -->  liquid + energy    Q is gas -->  liquid + energy    Q is negativenegative

liquid --> solid + energy   Q is negativeliquid --> solid + energy   Q is negative

When gaseous steam condenses on When gaseous steam condenses on your hand, OUCH!  Energy is being your hand, OUCH!  Energy is being given off by the steam to your hand.given off by the steam to your hand.

When liquid water freezes, it MUST When liquid water freezes, it MUST give off energy to the surroundings.give off energy to the surroundings.

Sample Problem for Specific Sample Problem for Specific HeatHeat

1. A 4.0 g sample of glass was heated 1. A 4.0 g sample of glass was heated from 274K to 314K, a temperature from 274K to 314K, a temperature increase of 40 K, and was found to increase of 40 K, and was found to have absorbed 32 J of energy as have absorbed 32 J of energy as heat. heat.

a. What is the specific heat of this a. What is the specific heat of this type of glass?type of glass?

B. How much energy will the same B. How much energy will the same glass sample gain when it is heated glass sample gain when it is heated from 314 to 344K? from 314 to 344K?

Sample Problems for Specific Sample Problems for Specific HeatHeat

2. Determine the specific heat of a 2. Determine the specific heat of a material if a 35g sample absorbed 96J as it material if a 35g sample absorbed 96J as it was heated from 293K to 313K.was heated from 293K to 313K.

3. A piece of copper alloy with a mass of 3. A piece of copper alloy with a mass of 85.0g is heated from 3085.0g is heated from 30°C to 45°C. In the °C to 45°C. In the process, it absorbs 523J of energy as heat.process, it absorbs 523J of energy as heat.

a. What is the specific heat of the copper a. What is the specific heat of the copper alloy?alloy?

b. How much energy will the same sample b. How much energy will the same sample lose if it is cooled from 45°C to 25°C?lose if it is cooled from 45°C to 25°C?

Sample Problems for Specific Sample Problems for Specific HeatHeat

4. Specific heat of gold is .129J/g4. Specific heat of gold is .129J/g°C. °C. How much energy is needed to raise How much energy is needed to raise the temperature of 5.0g of gold by the temperature of 5.0g of gold by 25°C?25°C?

5. Energy in the amount of 420J is 5. Energy in the amount of 420J is added to a 35g sample of water at a added to a 35g sample of water at a temperature of 10°C. What will be temperature of 10°C. What will be the final temperature of the water? the final temperature of the water?

Classification of MatterClassification of Matter Matter exists in an enormous variety of Matter exists in an enormous variety of

forms. Any sample of matter can be forms. Any sample of matter can be classified either as a pure substance or as a classified either as a pure substance or as a mixture. mixture.

Pure substances have the same composition Pure substances have the same composition throughout and does not vary from sample throughout and does not vary from sample to sample. A pure substance can be an to sample. A pure substance can be an element of a compound. element of a compound.

Mixtures, in contrast, contain more than one Mixtures, in contrast, contain more than one substance. They can vary in composition substance. They can vary in composition and properties from sample to sample and and properties from sample to sample and sometimes from one part of a sample to sometimes from one part of a sample to another part of the same sample. another part of the same sample.

MixturesMixtures You deal with mixtures everyday. Nearly You deal with mixtures everyday. Nearly

every object around you, including most every object around you, including most things you eat and drink and even the air things you eat and drink and even the air you breathe, is a mixture. you breathe, is a mixture.

A mixture is a blend of two or more kinds A mixture is a blend of two or more kinds of matter, each of which retains its own of matter, each of which retains its own identity and properties.identity and properties.

The parts, or components, of a mixture are The parts, or components, of a mixture are simply mixed together physically and can simply mixed together physically and can usually be separated.usually be separated.

As a result, the As a result, the properties of a properties of a mixture are a mixture are a combination of the combination of the properties of its properties of its components. components.

Because mixtures can Because mixtures can contain various contain various amounts of different amounts of different substances, a substances, a mixture’s composition mixture’s composition must be specified. must be specified. This is often done by This is often done by mass or by volume. mass or by volume. For example, a For example, a mixture might be 5% mixture might be 5% sodium chloride and sodium chloride and 95% water by mass.95% water by mass.

Some mixtures are uniform in Some mixtures are uniform in composition.composition.

These mixtures are said to be These mixtures are said to be homogeneous. They have the same homogeneous. They have the same proportions of components proportions of components throughout. throughout.

Homogeneous mixtures are also Homogeneous mixtures are also called solutions. A salt-water solution called solutions. A salt-water solution is an example of such a mixture. is an example of such a mixture.

Heterogeneous mixtures are not Heterogeneous mixtures are not uniform throughout. In a mixture of uniform throughout. In a mixture of clay and water, heavier clay particles clay and water, heavier clay particles concentrate near the bottom of the concentrate near the bottom of the container. container.

Methods of Separating Methods of Separating MixturesMixtures

Filtration – Using filter paper to Filtration – Using filter paper to separate the components of a separate the components of a mixture. mixture.

Centrifuge – A centrifuge can be used Centrifuge – A centrifuge can be used to separate some solid-liquid to separate some solid-liquid mixtures, such as blood. mixtures, such as blood.

Paper chromatography – Often used Paper chromatography – Often used to separate mixtures of dyes or to separate mixtures of dyes or pigments because the different pigments because the different substances move at different rates substances move at different rates on the paper.on the paper.

Titration – the Titration – the controlled addition controlled addition and measurement and measurement of the amount of a of the amount of a solution of known solution of known concentration concentration required to react required to react completely with a completely with a measured amount measured amount of a solution of of a solution of unknown unknown concentration.concentration.

Distillation – components of a Distillation – components of a mixture are separated on the basis of mixture are separated on the basis of boiling point, by condensation of boiling point, by condensation of vapor in a fractionating column. vapor in a fractionating column.

Pure SubstancesPure Substances

A pure substance has a fixed A pure substance has a fixed composition and differs from a composition and differs from a mixture in the following waysmixture in the following ways

1. Every sample of a given substance 1. Every sample of a given substance has exactly the same characteristic has exactly the same characteristic properties. properties.

2. Every sample of a given pure 2. Every sample of a given pure substance has exactly the same substance has exactly the same composition. composition.

Pure substances are either Pure substances are either compounds or elements. A compounds or elements. A compound can be decomposed, or compound can be decomposed, or broken down, into two or more broken down, into two or more simpler compounds or elements by simpler compounds or elements by chemical change. chemical change.

Sucrose (sugar) CSucrose (sugar) C66HH1212OO66 Under Under intense heating, sucrose breaks intense heating, sucrose breaks down to produce carbon and water. down to produce carbon and water.

Laboratory Chemicals and Laboratory Chemicals and PurityPurity

The chemicals in the laboratory are The chemicals in the laboratory are generally treated as if they are pure. generally treated as if they are pure. However all chemicals have some However all chemicals have some impurities. impurities.

The purity ranking of the grades can The purity ranking of the grades can vary where agencies differ in their vary where agencies differ in their standards.standards.

Introduction to the Periodic Introduction to the Periodic TableTable

Each small square on the periodic Each small square on the periodic table shows the symbol for the table shows the symbol for the element and the atomic number.element and the atomic number.

Groups or FamiliesGroups or Families These are the vertical columns on These are the vertical columns on

the periodic table. the periodic table. Each group contains elements with Each group contains elements with

similar propertiessimilar properties

PeriodsPeriods

The horizontal rows of elements in The horizontal rows of elements in the periodic table. Elements across a the periodic table. Elements across a period change regularly in their period change regularly in their physical and chemical properties. physical and chemical properties. However, elements closer together in However, elements closer together in a period tend to be more similar than a period tend to be more similar than those spread farther apart.those spread farther apart.

Metals, Nonmetals and Metals, Nonmetals and MetalloidsMetalloids

The periodic table in organized in The periodic table in organized in these three particular groupings. these three particular groupings. Metals are found on the left side of Metals are found on the left side of the staircase. Nonmetals are found the staircase. Nonmetals are found on the right side of the staircase. on the right side of the staircase.

Metalloids make up the staircase and Metalloids make up the staircase and have properties intermediate have properties intermediate between metals and nonmetals. between metals and nonmetals.

Specific Group NamesSpecific Group Names

Alkali metals = Group 1 (hydrogen is Alkali metals = Group 1 (hydrogen is the exception)the exception)

Alkaline earth metals = Group 2Alkaline earth metals = Group 2 Transition metals = Groups 3 – 12Transition metals = Groups 3 – 12 Halogens = Group 17Halogens = Group 17 Noble (rare) gases = Group 18Noble (rare) gases = Group 18