Matter and ChangeMatter and Change

Chapter 3Chapter 3

Matter Matter

Everything around usEverything around us Can be substancesCan be substances

(pure) by definition, with uniform and unchanging (pure) by definition, with uniform and unchanging compositioncomposition

Can be mixturesCan be mixtures Salt waterSalt water Nitrogen and oxygen (AIR)Nitrogen and oxygen (AIR)

Physical Properties of MatterPhysical Properties of Matter

Characteristics or behaviorCharacteristics or behavior Can identify substanceCan identify substance ExamplesExamples

Phys. State at partic. temperaturePhys. State at partic. temperature Melting point, boiling pointMelting point, boiling point Density [g/cmDensity [g/cm3 3 or g/mL or g/L]or g/mL or g/L] Extensive: depends on amount of substanceExtensive: depends on amount of substance

Extensive: depends on amount of substance. Extensive: depends on amount of substance. Ex: mass or volume of substance.Ex: mass or volume of substance.

Intensive: Independent of amount of Intensive: Independent of amount of substance. (Ex.: density, color, b.pt.)substance. (Ex.: density, color, b.pt.)

Chemical PropertiesChemical Properties

Ability (or lack of it) to combine or change Ability (or lack of it) to combine or change into a different substance.into a different substance. Iron (Fe) forms rust when exposed to oxygen in Iron (Fe) forms rust when exposed to oxygen in

air. (FeO)air. (FeO) Iron does not combine with nitrogen in air.Iron does not combine with nitrogen in air.

• See properties of copper p. 57See properties of copper p. 57

States of MatterStates of Matter

Solid: particles tightly packed, vibrate in place, Solid: particles tightly packed, vibrate in place, object has def. shape (indep. of container).object has def. shape (indep. of container).

Liquid: particles slip past each other, definite Liquid: particles slip past each other, definite volume, indefinite shape, dep. on container.volume, indefinite shape, dep. on container.

Gas: fills entire container, particles don’t Gas: fills entire container, particles don’t affect each other, shape & volume depends on affect each other, shape & volume depends on container.container.

Vapor is not always a gas. Might be a liquid.Vapor is not always a gas. Might be a liquid.

Physical and Chemical ChangesPhysical and Chemical Changes

Physical changes: altering a substance without Physical changes: altering a substance without changing its composition.changing its composition. Ex. Cutting, breaking, bending, grinding, Ex. Cutting, breaking, bending, grinding,

crumpling, crushing, etc.crumpling, crushing, etc. Also : condensation, boil’g, freez’g, vaporiz’g, Also : condensation, boil’g, freez’g, vaporiz’g,

melt’g.melt’g. (Phase changes are PHYSICAL changes)(Phase changes are PHYSICAL changes) Many times reversible.Many times reversible.

Chemical ChangesChemical Changes

When a new substance is formed.When a new substance is formed. Iron rusting, food digesting, gasoline Iron rusting, food digesting, gasoline

exploding.exploding. EVIDENCES of CHEM CHANGEEVIDENCES of CHEM CHANGE

Energy change (heat absorbed or released)Energy change (heat absorbed or released) Gas or odor producedGas or odor produced Color changeColor change Formation of a new solidFormation of a new solid

Conservation of MassConservation of Mass

Chem. rxns. been observed since we have Chem. rxns. been observed since we have observed world.observed world.

Late 18Late 18thth century (1700’s) these were 1 century (1700’s) these were 1stst quantified (measured).quantified (measured).

Lavoisier discovered the Law of Conservation Lavoisier discovered the Law of Conservation of Massof Mass Mass is not created nor destroyed during chem. Mass is not created nor destroyed during chem.

reaction; it is conserved. P.64, prob. P.65reaction; it is conserved. P.64, prob. P.65

Mixtures of MatterMixtures of Matter

Mixture: combination of 2 or more substances Mixture: combination of 2 or more substances in which each retains its individual properties.in which each retains its individual properties. Composition variesComposition varies Number of mixtures possible is infiniteNumber of mixtures possible is infinite Can be separated by differences in physical Can be separated by differences in physical

properties.properties.

Methods of SeparationMethods of Separation

Reaction to a magnetic fieldReaction to a magnetic field Filtration of a solid from a liquidFiltration of a solid from a liquid Distillation of 2 or more liquids from each Distillation of 2 or more liquids from each

other, based on diff. boil’g. pts. other, based on diff. boil’g. pts. Crystallization: sep. 2 solids from each other.Crystallization: sep. 2 solids from each other. Chromatography: based on chem. polarity diff. Chromatography: based on chem. polarity diff.

of molecules.of molecules.

Types of MixturesTypes of Mixtures

Heterogeneous: individual parts or phases Heterogeneous: individual parts or phases distinctly seen. distinctly seen.

Homogeneous: looks the same throughoutHomogeneous: looks the same throughout Can be solutionsCan be solutions Top same as bottomTop same as bottom Ex vanilla ice cream, margarine, mixed koolaidEx vanilla ice cream, margarine, mixed koolaid

Elements and CompoundsElements and Compounds

Elements and Compounds are both types of Elements and Compounds are both types of pure substancespure substances

Element : cannot be divided further by Element : cannot be divided further by physical or chem. means.physical or chem. means.

Smallest unit is the atom.Smallest unit is the atom. 91 natural ones, rest man-made.91 natural ones, rest man-made.

Periodic TablePeriodic Table

Chart organized according to their chem. Chart organized according to their chem. activity.activity.

Horiz. rows called periods.Horiz. rows called periods. Vertical columns called groups or families.Vertical columns called groups or families. Predictions can be made from it.Predictions can be made from it. Mendeleev developed 1Mendeleev developed 1stst one. one.

CompoundsCompounds

2 or more elements chemically bonded 2 or more elements chemically bonded together.together.

Smallest unit is a molecule (atoms bonded Smallest unit is a molecule (atoms bonded together)together)

Ex. Water, HEx. Water, H22O, salt, NaCl, sugar, CO, salt, NaCl, sugar, C1212HH2222OO1111

10 million cpds known, 100,000 new each yr.10 million cpds known, 100,000 new each yr.

Law of Definite ProportionsLaw of Definite Proportions

A compound is always composed of the same A compound is always composed of the same elements in the same proportions.elements in the same proportions.

Water is always 11% H and 89% O.Water is always 11% H and 89% O. COCO22 is always 27.3% C, 72.7% O. is always 27.3% C, 72.7% O. Table on p.75Table on p.75 Prac. Prob. P.76Prac. Prob. P.76

Compounds can be broken into elements Compounds can be broken into elements they are made of.they are made of.

Liquid HLiquid H22O→ HO→ H2 2 gas+ O gas+ O22 gas p.74 gas p.74

NaCl crystals → Na solid + ClNaCl crystals → Na solid + Cl2 2 gas p.74 gas p.74

Law of Multiple ProportionsLaw of Multiple Proportions

When 2 elements combine to produce 2 When 2 elements combine to produce 2 different compounds, the mass of one element different compounds, the mass of one element that combines with a given amunt of the other that combines with a given amunt of the other element will vary by small whole number element will vary by small whole number ratios.ratios.

Ex. CO and COEx. CO and CO22 :12 grams C combine with 16 :12 grams C combine with 16 grams O in CO, but in COgrams O in CO, but in CO22 12 grams C 12 grams C combine with 32 grams O(twice as much O). combine with 32 grams O(twice as much O). Table p.76Table p.76

Some differences in these 2 laws:Some differences in these 2 laws: Law of def. proport. deals with 1 compound only.Law of def. proport. deals with 1 compound only. Law of mult. proport. Deals with 2 compounds at a Law of mult. proport. Deals with 2 compounds at a

time. time.

Other ex. NOOther ex. NO22 and N and N22OO33,,

or PClor PCl3 3 and PCl and PCl55, or SF, or SF44 and SF and SF66..