Unit 1 Matter, Measurement, and The Language of Chemistry SAVE PAPER AND INK!!! When you print out...

Unit 1

Matter, Measurement, and The Language of Chemistry

SAVE PAPER AND INK!!! When you print out the notes on

PowerPoint, print "Handouts" instead of "Slides" in the print

setup. Also, get rid of background shading by

selecting “Pure Black & White” instead of “Grayscale.”

Matter

• Matter – anything that has mass and occupies space.• Matter can be classified according to its state (solid,

liquid or gas.)

Matter (continued)

• Matter can also be classified according to its composition:

Matter (continued)

• Pure Substance – Composed of only a single type of atom or molecule.– Element – Composed of only one type of atom.

Cannot be chemically broken down into simpler substances.

– Compound – Composed of two or more elements in fixed, definite proportions.

• Mixture – Composed of two or more different types of atoms or molecules that can be combined in variable proportions.

Heterogeneous Mixtures

• A heterogeneous mixture consists of visibly different substances.

Homogeneous Mixtures

• A homogeneous mixture has the same uniform appearance and composition.

Properties of Matter

• Physical Properties – Characteristics of a substance that you can observe. – Examples: mass, volume, color, shape, odor,

texture, melting point, boiling point, density.

• Chemical Properties - Characteristics of a substance that describe how it can be changed into a new substance. – Examples: flammability, corrosiveness, reactivity,

acidity, toxicity.

Changes in Matter• Physical Change – A change in physical

properties, it is still the same substance.

• Chemical Change – The change of a substance into a new, different substance.

Metric Measurement

• Metric System – The standard measurement system used by scientists around the world. Also called the International System of Units, or SI. It is a decimal system, based on the number 10 and multiples of 10.

Length

• The basic metric unit of length is the meter (m).– A meter is a little longer than

a yard. A meter is a typical height for a 3-year old child, or about the size of two cocker spaniels.

Mass

• The basic metric unit of mass is the gram (g). Mass is measured with a balance.– A gram is small. A nickel coin has

a mass of about 5 g.– To measure larger amounts of mass,

a kilogram (kg) is usually used. A kg is bigger than a pound. A 132 lb. person would have a mass of 60 kg.

Temperature

• The SI unit for temperature is the kelvin (K).• Absolute zero – 0 K (-273oC) the coldest

temperature possible, where all molecular motion stops.

• You can convert betweentemperature scales with the following formulas:

K = oC + 273

oC = (oF -32) / 1.8

Volume

• The basic metric unit of volume is the liter (L).• One milliliter (ml) is the same as one cubic

centimeter (cm3.)– 2 L is the common size for a bottle

of soda.– 1 ml doesn’t even

fill up a teaspoon.

Density

• Extensive Properties depend on the amount of the substance. Examples: Mass, Volume.

• Intensive Properties (also called characteristic properties) are independent of the amount of the substance. They can be used to identify substances. Example: Density.

• Density is the ratio of mass to volume:

Density = MassVolume

Significant Figures

• the non-place-holding digits in a reported measurement are called significant figures.

• All non-zero numbers are significant, but some zeros in a written number are only there to help you locate the decimal point.

• How do you remember which zeros are significant and which are not?

Significant Figures

Pacific (Present) -If decimal point is present, start with the first non-zero number on the left.

Atlantic (Absent) -If decimal point is absent, start with the first non-zero number on the right.

• The Atlantic – Pacific Rule:

Significant Figures

• Examples: How many significant figures?

99,000 2 sig figs

99,000. 5 sig figs0.0099 2 sig figs

0.0990 3 sig figs

Calculating with Significant Figures• When you use your measurements in calculations,

your answer may only be as exact as your least exact measurement.

• For addition and subtraction, round to the fewest decimal places.

Example: (3 decimals) (1 decimal) (unrounded) (rounded) 50.259 + 17.4 = 67.659 67.7

• For multiplication and division, round to the fewest significant figures.

Example: (3 sigfigs) (1 sigfig) (unrounded) (rounded) 0.135 x 20 = 2.7 3

Uncertainty in Measurement• Uncertainty comes from limitations of measuring

devices, experimental design, experimenter, and nature’s random behavior.

• Accuracy – how closea measurement comesto the actual value.

• Precision – how closemeasurements are to one another, or how reproducible they are.

Not Accurate and Not Precise

Accurate but Not Precise

Not Accurate but Precise

Accurate and Precise

Accuracy vs. Precision

Chemical Formulas

• A chemical formula indicates the number of each kind of atom in a chemical compound.

• when there is no subscript next to an atom, the subscript is understood to be 1.

Examples:

octane — C8H18

aluminum sulfate — Al2(SO4)3

there are 8 carbon atoms in the molecule.

there are 18 hydrogen atoms in the molecule.

there are 2 aluminum atoms in the formula unit.

Parentheses surround the polyatomic ion to identify it as a group. There are 3 SO4

- groups.

Chemical FormulasSample Problem

Count the number of atoms in the following chemical formulas:

Solution:a.Ca(OH)2

b.KClO3

c.NH4OH

d.Fe2(CrO4)3

1 Calcium, 2 Oxygens,

and 2 Hydrogens

1 Potassium, 1 Chlorine, and 3 Oxygens

1 Nitrogen, 5 Hydrogens, and 1 Oxygen

2 Irons, 3 Chromiums,

and 12 Oxygens

Metals and Nonmetals

• Metals tend to form positive (+) ions, Nonmetals tend to form negative (-) ions.

Monoatomic Ions

• Monoatomic Ions are ions formed from a single atom.

• Some main-group elements tend to form covalent bonds instead of ions (ex. C and Si.)

+1+2 +3 -1-2-3

Monoatomic IonsSample Problem

Identify each element as either a metal or a nonmetal. For main group elements, specify the ion that will form:

Metal or Nonmetal: Ion:a.Nab.Cuc.Od.Aue.Baf.Hg.Nh.Al

metalmetal

nonmetalmetalmetal

nonmetalnonmetal

metal

+1

-2

+2+1-3+3

Chemical Categories by Formula

• Ionic Compounds – Formed from metal (+) ions and nonmetal (-) ions.– Base – formula ends with the hydroxide ion (OH-1)

(ex. KOH, Ca(OH)2, Al(OH)3)

– Metallic Oxide – consists of only 2 elements: 1 metal and oxygen (ex. Na2O, MgO, SnO2)

– Oxysalt – contains the element oxygen in the form of a polyatomic ion (ex. MgSO3, Ni(ClO3)2)

– Salt – an ionic compound that can’t be classified into a more specific category (ex. NaCl, CuBr2)

Chemical Categories by Formula (continued)

• Molecular Compounds – Formed from two or more nonmetals.– Non-metallic Oxide – consists of only 2 elements:

1 nonmetal and oxygen (ex. CO2, SO3, P4O10)

– Hydrocarbon – consists of only 2 elements: carbon and hydrogen (ex. CH4, C2H4, C3H8)

• Acids – formula begins with hydrogen (H+).– Binary acid – contains hydrogen and one other

element (ex. HCl, H2S, HBr)

– Oxyacid – contains oxygen in a polyatomic ion (ex. HNO3, H2SO4, H3PO4)

Chemical Categories by FormulaSample Problem

To which category does each of the following chemical formulas belong?:

Category:a.BaSO3

b.Ag2Oc.Ca(OH)2

d.NiF2

e.C4H10

f.HNO2

g.PO5

h.HF

oxysaltmetallic oxide

basesalt

hydrocarbonoxyacid

nonmetallic oxidebinary acid

Nomenclature Flowchart

Compounds

Ionic Molecular

Binary HydratesPrefixSystem

Acids

Hydro-carbons

BinaryAcids

Oxyacids

Compounds

Ionic

Binary

PolyatomicIons

Naming Binary Ionic Compounds

• Binary Compounds are composed of 2 elements.• The name of the metal (+) ion is given first,

followed by the name of the nonmetal (-) ion.• The first element in the compound

is identified simply by its name.• For the second element, the

ending of the its name is dropped, and the ending -ide is added.

Examples: Al2O3 KF

aluminum potassium

oxide fluoride

Writing Binary Ionic Compounds• Rules for writing binary ionic compounds:

1. Write the symbols for the ions, and their charges.Remember: The metal (+) ion is always written first.

2. Cross over the charges (use the absolute value of each ion’s charge as the subscript for the other ion.)

3. Simplify the numbers and remove the 1’s.Example: aluminum oxide

The correct formula for aluminum oxide is

Al3+

Al2O3

3O2–2

Binary Ionic CompoundsSample Problem

Write chemical formulas for :

a.Magnesium Iodide

b.Calcium Oxide

Write the correct names for:

a.Li2S

b.ZnCl2

Solution:

Hint: Always divide subscripts by their largest common factor .

Lithium

Zinc

Mg2+2I –

1

Ca2+2O 2–

2

MgI2

CaO

Lithium Sulfide

Zinc Chloride

The Stock System• Most d-block elements (transition

metals) can form 2 or more ions with different charges.

• To name ions of these elements, scientists use the Stock system, designed by Alfred Stock in 1919.

• The system uses Roman numerals to indicate an ion’s charge.Example: Fe2+

Fe3+

iron(II)iron(III)

Stock System NamingSample Problem A

Write the formula and give the name for the compound formed by the ions Cr3+ and F–.Solution:

Write the ions side by side, cation first.

Cross over the charges to give subscripts.

Chromium forms more than one ion, so its name must include the charge as a Roman numeral.

Cr3+3F –

1

CrF3

Chromium (III) Fluoride

2

I –

O 2–

Stock System NamingSample Problem B


a.Tin (IV) Iodide

b.Iron (III) Oxide


a.VF3

b.CuO

Solution:

Hint: “Uncross” subscripts to get the charges of the ions.

Vanadium (III)Copper (II)

Sn4+41

Fe3+32

SnI4

Fe2O3

Fluoride

Oxide

Be sure to verify the charge of the anion.

V3+

F3-

Cu+

O -2


Compounds

Ionic Molecular

BinaryPrefixSystem

Acids

Hydro- carbons

BinaryAcids

Oxyacids

Compounds

Ionic

Hydrates

PolyatomicIonsPolyatomicIons

Polyatomic Ions

• A polyatomic ion is a charged group of covalently bonded atoms.

• Common endings are -ate or -ite, but there are exceptions.

• For more than 1 polyatomic ion, use parentheses with the subscript on the outside.

Example: Al2(SO4)3There are 3 sulfate ions

in this compound

Common Polyatomic Ions

(NO3)2


a.Calcium Hydroxide

b.Tin (IV) Sulfate


a.(NH4)3 PO4

b.Cu(NO3)2

Sn4+ SO4 2–

OH –

Polyatomic IonsSample Problem

Solution:

Hint: Remember to divide subscripts by their largest common factor .

Ammonium

Copper(II)

Ca2+21

42

Ca(OH)2

Sn(SO4)2

Phosphate

NitrateHint: “Uncross” subscripts to get the charges of the ions.

Cu2+ -


Compounds

Ionic Molecular

BinaryPrefixSystem

Acids

Hydro- carbons

BinaryAcids

Oxyacids

Compounds

Ionic

Hydrates

PolyatomicIons

Hydrates

Hydrates

• Hydrates – ionic compounds that contain a specific number of watermolecules associated with eachformula unit.

• in formula, attached waters follow.• in name, attached waters indicated by

adding “prefixhydrate” after name of ionic compound.Example: CoCl2 6H∙ 2O cobalt(II) chloride hexahydrate

Prefix No. of Waters

hemi ½

mono 1

di 2

tri 3

tetra 4

penta 5

hexa 6

hepta 7

octa 8


a.calcium sulfate hemihydrate

b.barium chloride hexahydrate


a.CuSO4 • 5H2O

b.LiF • 4H2O

HydratesSample Problem

Solution:

copper (II) sulfate

lithium fluoride

CaSO4 • ½ H2O

BaCl2 • 6H2O

pentahydrate

tetrahydrate


Compounds

Ionic Molecular

BinaryPrefixSystem

Acids

Hydro- carbons

BinaryAcids

Oxyacids

Compounds

Molecular

PrefixSystemHydrates

PolyatomicIons

The Prefix System

• Molecular compounds are composedof covalently-bonded molecules.

• The old prefix system is still used for molecular compounds.

• Name the prefix, then the element. Anions end in -ide.

• The prefix mono- usually isn’t used for cations.Examples: P4O10

COtetraphosphorus decoxidecarbon monoxide

The Prefix SystemSample Problem


a.dinitrogen trioxide

b.carbon tetrabromide


a.As2S3

b.PCl5

Solution:

diarsenic

phosphorus

N2O3

CBr4

trisulfide

pentachloride

Hydro- carbons


Compounds

Ionic Molecular

BinaryPrefixSystem

Acids

Hydro- carbons

BinaryAcids

Oxyacids

Compounds

Molecular

Hydrates

PolyatomicIons

Hydrocarbons• Hydrocarbons are compounds that contain

only carbon and hydrogen.• Most fuels are mixtures of hydrocarbons.• Hydrocarbons containing only single bonds

are called alkanes. Naming is based on the number of carbons , and the suffix –ane is added.

Base Name No. of C Base Name No. of C

meth- 1 hex- 6

eth- 2 hept- 7

prop- 3 oct- 8

but- 4 non- 9

pent- 5 dec- 10

HydrocarbonsSample Problem


a.methane

b.butane


a.C2H6

b.C3H8

Solution:

ethane

propane

CH4

C4H10

Hydro- carbons


Compounds

Ionic Molecular

BinaryPrefixSystem

Acids

BinaryAcids

Oxyacids

Compounds

Acids

BinaryAcids

OxyacidsHydrates

PolyatomicIons

Acids

• An acid is a certain typeof molecular compound.All acids start with H (e.g. HCl, H2SO4).

• Acids can be divided into two categories:1. Binary acids are acids that consist of H and a

non-metal. (e.g. HCl.)2. Oxyacids are acids that contain H and a

polyatomic ion that includes O (e.g. H2SO4.)

Binary Acids

• General rules for naming a binary acid:1. Begin with the prefix hydro-.2. Name the anion, but change the ending

to –ic.3. Add acid to the name.Examples:HCl, hydrochloric acid.HBr, hydrobromic acid.H2S, hydrosulfuric acid.

Oxyacids

• General rules for naming an oxyacid :1. Name the polyatomic ion.2. Replace -ate with -ic or -ite with -ous3. Add acid to the name.Examples:H2SO4, sulfuric acid.

H2SO3, sulfurous acid.

HNO3, nitric acid.

HNO2, nitrous acid.

sulfate

Naming AcidsSample Problem

Write the correct name for each of the following:

a.HF

b.HNO2

c.H2S

d.H2SO4

e.H3PO4

Type of Acid:binary acid

oxyacid

Name:hydro nitrite

fluorineic acid

binary acid hydro

sulfuric acid

ous acid

oxyacid uric acidoxyacid phosphateoric acid

Heat and Temperature

• Temperature – a measure of the average kinetic energy of the particles in a sample of matter.

• The greater the kinetic energy of the particles in a sample, the hotter it feels.

• Heat – energy transferred between samples of matter due to a difference in their temperatures.

• Heat always moves spontaneously from matter at a higher temperature to matter at a lower temperature.

Measuring Heat

• Heat energy is measured in joules (or calories – food only)

• Chemical reactions usually either absorb or release energyas heat.

• The energy absorbed or released as heat in a chemical or physical change is measured in a calorimeter.

Specific Heat

• A quantity called specific heat canbe used to compare heat absorptioncapacities for different materials.

• Specific heat – the amount of energy required to raise the temperature of one gram of a substance by 1°C or 1 K.

• Specific heat can be measured in units of J/(g•°C), J/(g•K), cal/(g•°C), or cal/(g•K).

Heat Transfer Equation

• Specific heat can be used to find the quantity of heat energy gained or lost with a change in temperature according to the following equation:

• Where the variables stand for the following:Q = heat transferred (joules or calories)m = mass (g)cp = specific heat∆T = change in temperature (oC or K)

Q = m•cp•∆T

Heat Transfer EquationSample Problem

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

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

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

Q = m x cp x ∆T 32 J = (4.0 g)(cp) (40. K)

cp = (4.0 g)(40. K)

32 J = 0.20 J/(g•K)

Q = m x cp x ∆T Q = (4.0 g)(0.20 J/(g•K)) (30 K) = 24 J

Unit 1 Matter, Measurement, and The Language of Chemistry SAVE PAPER AND INK!!! When you print out...

Documents

Transcript of Unit 1 Matter, Measurement, and The Language of Chemistry SAVE PAPER AND INK!!! When you print out...