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Chapter 2“Matter and Change”p. 38

Describing MatterProperties:

1) Extensive – depends on amt of matter in sample

- ex’s. mass, volume, calories, magnetism

2) Intensive – depends on type of matter, not amt.

- Hardness, Density, B.P.- All samples of same substance have

same intensive prop’s. (same composition)

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Identifying SubstancesPhysical Properties- observed & measured w/o changing composition◦color, hardness, m.p., b.p.

Chemical Properties- observed by changing comp of material ◦ability to burn, decompose, ferment, react w/, etc.

States of matter1) Solid- cannot flow (definite

shape & volume)2) Liquid- definite vol - takes shape

of container (flows)3) Gas- w/o definite vol or shape &

flows◦ Vapor- gaseous but normally liquid or solid @

room temp water “gas”, or water “vapor”?

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Three Main Phases – page 41

States of Matter

Solid

Liquid

Gas

Definite Volume?

YES

YES

NO

Definite Shape?

YES

NO

NO

Result of aTemperature Increase?

Small Expans.

Small Expans.

Large Expans.

Will it Compress?

Not easily

YES

Not easily

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4th state: Plasma - formed at hi temps; ionized phase of matter (Sun)

Solid Liquid Gas

Melt Evaporate

CondenseFreeze

Sublime

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Physical vs. Chemical ChangePhysical change changes visible appearance w/o changing comp of material◦Boil, melt, cut, bend, split, crack◦Is boiled water still water?

Reversible, or irreversibleChemical change - change where new substance formed◦Rust, burn, decompose, ferment

Section 2.2 Mixturesp. 44

Mixture - physical blend of 2+ components

1) Heterogeneous – uniform in comp• Choc chip cookie, gravel, soil

2) Homogeneous - same comp thruout(solutions)

• Kool-aid, air, salt water Every part keeps own prop’s

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Solutions - homogeneous mixtures

Mixed molecule by molecule, so too small to see diff pts

occurs btwn any state of matter: gas-gas; liquid-gas; gas-liquid; solid-liquid; solid-solid (alloys)◦Steel (Fe, Cr & Ni)

Phase?

“phase” describes any pt of sample w/ uniform comp of properties

A homogeneous mixture consists of a single phase

A heterogeneous mixture consists of two or more phases.

Note Figure 2.6, page 45

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Separating MixturesSome by physical means: rocks & marbles, iron filings & sulfur (magnet)

Differences in physical props used to separate mixtures

Filtration - separates solid from liquid in hetero mix. (by size) –Figure 2.7, page 46

Separation of a MixtureDistillation: takes advantage of different boiling pts.

NaCl boils at 1415 oCH2O boils at 100 oCMg boils at 1107 oC

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Separation of a MixtureComponents of dyes such as ink may be separated by paper chromatography.

Chromatography video

Forensic Ink Analysis

Applications of Chromatography 2 Greek words: ◦ chroma "color" and “graphein "to write"

Biological labs: ◦ ID amino acids ◦ detects drugs in urine

Environmental labs: ◦ ID contaminants in waste oil ◦ pesticides in groundwater ◦ test drinking water & test air quality

Pharmaceutical companies ◦ prepare quantities of extremely pure materials.

Food industry ◦ ID contaminants like aflatoxin naturally occurring toxin produced by fungus

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Sec 2.3 Elements & Compounds p. 48

Substances are either:a) elements, orb) compounds

Pure Substances

Element Compound

Simplest matter

1 type of atom

Cannot be broken down

Broken down by

chemical methods

different prop’s thanelements

2+ atomschemicallycombined

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Compounds v.s. MixturesMixtures

Made of more thanone kind of material

Made by a physical change

Variablecomposition

Compounds

Made of one kindof material

Made by a chemical change

Definitecomposition

Which is it?

ElementCompoundMixture

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Chemical Change

1+ substances are converted into different substances.

Heat & lightoften indicate chem chg

A “chemical change” chg producing matter w/ diff. comp than original matter

Classification of Matter

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Symbols & Formulas

118 elements 1 - 2 letter symbol 1st letter CAP; 2nd

letter lowercase ◦ B, Ba, C, Ca

Some names Latin◦ Table 2.2, page 52

cmpds have formula◦ H2O, NaCl, C12H22O11

Chemical Changes

Chemical property - ability of substance to undergo specific chem change •Fe + O = rust•rusting - chem prop of Fe

During chem chge comp of matter always changes

Sec 2.4 Chemical Rxns p. 53

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Chemical Rxns are…When 1+ substances changed into new substances

Reactants- start w/Products- end w/Products have NEW PROPS diff from reactants

Arrow points from reactants tonew products

Recognizing Chemical Changes1) Energy absorbed/released (temp

changes hotter/colder)2) Color changes3) Gas production (bubbling, fizzing, or

odor change; smoke)4) precipitate forms - solid separates

from solution (won’t dissolve)5) Irreversibility - not easily reversedSome ex’s not chem – boiling water

bubbles, choc syrup in milk, etc.

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Conservation of Mass During any chem rxn, product mass = reactant mass

All mass accounted for:◦Burning wood results in products that appear to have less mass (ashes)….◦CO2 & H2O vapor

Law of conservation of mass

- Page 55

reactants = product

43.43 g Original mass = 43.43 g Final mass