CHAPTER 1*Introduction: Matter and

MeasurementSuh Kwon

1.1 – The Study of Chemistry

The Molecular Perspective of Chemistry• Matter = physical material of the universe that has

mass and occupies space

• Element = substance that cannot be separated into simpler substances by chemical means

• Atom = almost infinitesimally small building blocks of matter

• Molecules = chemical combination of two ore more atoms

1.2 – Classifications of Matter

States of MatterSolid Liquid Gas

Both a definite shape and a definite volume

Distinct volume independent of its

container but has no specific shape

No fixed volume or shape; conforms to the volume or shape of its

container

Rigid

Assumes the shape of the portion of the container that it

occupies

Can compress or expand to occupy a

smaller or larger volume

Molecules are held tightly together, usually in definite arrangement; wiggling only slightly

Molecules are packed more closely together, but still move rapidly allowing them to slide

over each other

Molecules are far apart and are moving at high

speeds, colliding repeatedly with each

other

Pure Substances and Mixtures• Pure Substance (referred to as a substance)=

matter that has a fixed composition and distinct properties Classified as either ..

– Elements (composed of only one kind of atom)

– Compounds (composed of two ore more elements)

• Mixture = combinations of two or more substances in which each substance retains its own chemical identity and its own properties; compositions vary Heterogeneous = do not have the same composition,

properties, and appearance throughout the mixtures (Ex: sand, rocks, and wood)

Homogeneous = uniform throughout the mixtures(Ex: air, such as nitrogen, oxygen, etc)

Separation of Mixtures• Filtration (for heterogeneous mixtures)

Ex: to separate iron filings from gold ones, use a magnet to attract the iron

• Distillation (for homogeneous mixtures) Ex: to separate salt from water, boil the solution; thus,

water will evaporate while the salt is left behind because water has a much lower boiling point than table salt

• Chromatography

https://www.crimescene.com/store/bmz_cache/b/b3ac10ad9721f4d3399d6f4b82111806.image.220x223.jpg*

1.3 – Properties of Matter Physical properties = w/o changing identity and

composition; (color, odor, density, melting point, boiling point, and hardness)• Ex: When water evaporates, it changes from liquid to gas;

however, its composition does not change; it is still water Chemical properties = substance that may change or

react to form other substances• Ex: Flammability, which is the ability to burn a substance in

the presence of oxygen, transforms one substance into a chemically different one

Intensive properties = does not depend on the amount of the sample being examined; (temperature, melting point, and density)

Extensive properties = depend on the quantity and amount of the sample; (measurements of mass and volume)

1.4 – Units of Measurement SI Units

Physical Quantity

Name of Unit Abbreviation

Mass Kilogram kg

Length Meter m

Time Second sa

Electric current Ampere A

Temperature Kelvin K

Luminous intensity Candela cd

Amount of substance Mole mol

Derived SI Units• Density = mass

volume

Practice Problem!!:

** Calculate the density of mercury if 1.00 x 102 g occupies a volume of 7.36 cm3.

(Answer)

Density = mass = 1.00 x 102 g = 13.6 g/cm3

volume 7.36 cm3

1.5 – Uncertainty in Measurement

Precision and Accuracy• Precision = a measure of how closely individual

measurements agree with one another

• Accuracy = how closely individual measurements agree with the correct, or “true” value

http://celebrating200years.noaa.gov/magazine/tct/accuracy_vs_precision_556.jpg*

Significant Figures• Guidelines to determine the number of sig. figures:

Nonzero digits are always significant(214= THREE significant figures)

Zeros between nonzero digits are always significant(1004 = FOUR significant figures)

Zeros at the beginning of a number are never significant(0.01 = ONE significant figure)

Zeros that fall both at the end of a number and after the decimal point are always significant

(4.0 = TWO significant figures)

Significant Figures in Calculations

• Multiplication and Division: the result must be reported with the same number of significant figures as the measurement with the fewest significant figures

• Addition and Subtraction: the result cannot have more digits to the right of the decimal point than any of the original numbers

1.6 – Dimensional Analysis