chapter 1: introduction classification of matter matter can exist in different forms or phases: (1)...
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Chapter 1: IntroductionChapter 1: Introduction
Classification of Matter
Matter can exist in different forms or phases:
(1) States of Matter
solid liquid gas
Chapter 1: IntroductionChapter 1: Introduction
Classification of Matter
solid liquidgas
Chapter 1: IntroductionChapter 1: Introduction
Classification of Matter
Solid
Liquid
Gas
Definedshape?
Defined volume?
Distancebetween molecules?
Compressible?
Yes
No
No
Yes
Yes
No
Small
intermediate
large
No
No
Yes
Chapter 1: IntroductionChapter 1: Introduction
Classification of Matter
(2) Molecules, Elements, Compounds, Pure Substances, and Mixtures
Molecules:
→ contain more than one atom
→ atoms may be the same or different types
atom
Chapter 1: IntroductionChapter 1: Introduction
Classification of Matter
Elements:
→ contains one unique kind or atom
→ may consist of atoms or molecules
(2) Molecules, Elements, Compounds, Pure Substances, and Mixtures
Chapter 1: IntroductionChapter 1: Introduction
Classification of Matter
Compounds:
→ composed of two or more elements
→ contain more than one type of atom
(2) Molecules, Elements, Compounds, Pure Substances, and Mixtures
Chapter 1: IntroductionChapter 1: Introduction
Classification of Matter
Pure Substance:
→ has distinct properties
→ can be element or compound
(2) Molecules, Elements, Compounds, Pure Substances, and Mixtures
Chapter 1: IntroductionChapter 1: Introduction
Classification of Matter
Mixtures:
→ properties vary between samples
→ contain different substances
(2) Molecules, Elements, Compounds, Pure Substances, and Mixtures
Chapter 1: IntroductionChapter 1: Introduction
Classification of Matter
Homogeneous Mixtures <-> Heterogeneous Mixtures
(2) Molecules, Elements, Compounds, Pure Substances, and Mixtures
→ uniform→ solutions (solid, liquid, gas)
Air
Oil on water
Chapter 1: IntroductionChapter 1: Introduction
Homogenous or Heterogeneous Mixtures?
GraniteMud
Coffee - a
heterogeneousheterogeneous
homogeneous
Coffee - b
heterogeneous
Water and flour
heterogeneous
Vinaigrette
heterogeneous
Brass
homogeneous
Chapter 1: IntroductionChapter 1: Introduction
Chapter 1: IntroductionChapter 1: Introduction
Classification of Matter
(2) Molecules, Elements, Compounds, Pure Substances, and Mixtures
Molecules or atoms?
Molecules Atoms Atoms Molecules and atoms
Compound? yes no no no
Phase state? gas solid and gas solid gas
Mixture?
- what kind?
no yes yes yes
- heterogeneous homogeneous homogeneous
Chapter 1: IntroductionChapter 1: Introduction
Mixtures can be separated
Filtration
Distillation
Chromatography
... for example by
Chapter 1: IntroductionChapter 1: Introduction
Properties of Matter
Physical Properties & Changes
Chemical Properties & Changes
→ no change in identity or composition of substance
→ how a substance reacts to form a different substance
Chapter 1: IntroductionChapter 1: Introduction
Properties of Matter
Melting of ice:
Physical process phase changes but it's still H
2O
Burning of wood:
Chemical process conversion to CO
2 and H
2O
Chapter 1: IntroductionChapter 1: Introduction
Physical of Chemical Property?
Zinc (Zn):
silver-grey metal
melting point: 420oC
generates hydrogen whendissolved in sulfuric acid
density (25oC) = 7.13 g/cm3
reacts with oxygen to formZinc oxide (ZnO)
Physical property
Physical property
Chemical property
Physical property
Chemical property
Chapter 1: IntroductionChapter 1: Introduction
Physical or Chemical Process?
Sugar dissolving in water. Physical process
a) compounds in the gas phase
b) elements in the gas phase
c) molecules in the gas phase
d) a heterogeneous mixture of
elements
e) a mixture of molecules in the
liquid phase
The picture on the left represents
Chapter 1: IntroductionChapter 1: Introduction
Intensive Properties……are independent of the amount of substance
Extensive Properties……depend on the amount of substance
Boiling/melting point (bp/mp)
Mass
Volume
Density
Intensive property
Extensive property
Extensive property
Intensive property
Chapter 1: IntroductionChapter 1: Introduction
A gold nugget (1 cm x 0.5 cm x 0.7 cm) has a density of 19.3 g/cm3.
A jeweler decides to use this gold nugget to make a perfect gold
sphere with a diameter of 0.4 cm. What is the density of this sphere?
Density is an intensive property which is independent of quantity.The density of gold is independent of shape or size: 19.3 g/cm3
Chapter 1: IntroductionChapter 1: Introduction
Units of Measurement: Temperature
K = OC + 273
Chapter 1: IntroductionChapter 1: Introduction
Units of Measurement
Système International d'Unités (SI units)
Mass kilogram kgLength meter mTime second sTemperature Kelvin KAmount of a substance mole mol
Chapter 1: IntroductionChapter 1: Introduction
Units of Measurement
Prefixes used in the metric system:
You ABSOLUTELY MUST know these (Table 1.5 page 14):
Giga G gigameter (Gm) = 109 mMega M megameter (Mm) = 106 m
Kilo K kilometer (Km) = 103 mmeter (m) = 1 m
Deci d decimeter (dm) = 10-1 m Centi c centimeter (cm) = 10-2 mMilli m millimeter (mm) = 10-3 m
Micro µ micrometer (µm) = 10-6 mNano n nanometer (nm) = 10-9 m
Pico p picometer (pm) = 10-12mFemto f femtometer (fm) = 10-15m
Chapter 1: IntroductionChapter 1: Introduction
Units of Measurement: Derived Units
Volume:
1m 1m
1m (1 m)3 = 1m3 = 1cubic meter
1cm 1cm
1cm (1 cm)3 = 1cm3 = 1cubic centimeter = 1mL
cmin
cmin 9.58
1
54.22.23
Chapter 1: IntroductionChapter 1: Introduction
Dimensional Analysis
Converting inches into cm:
- the units to be eliminated go on opposite sides of the fraction
Conversion factor:same quantity but in different units
Converting m/min into m/s:
1.2mmin
× 1min60 s
= 0.020 ms
Conversion factor
Chapter 1: IntroductionChapter 1: Introduction
Dimensional Analysis
Conversions involving squared and cubic units:
The volume of a container is 5.3 m3. What is the volume in cm3?
=> Convert m3 into cm3
5.3 m3 × 100 cm1 m
Units must match in order to cancel out!
Chapter 1: IntroductionChapter 1: Introduction
Dimensional Analysis
Conversions involving squared and cubic units:
The volume of a container is 5.3 m3. What is the volume in cm3?
=> Convert m3 into cm3
5.3 m3 × 1003 cm3
13 m3= 53,00000 cm3
= 5.3 × 1000000 cm3
= 5.3 × 106 cm3
Units must match = cube both number AND unit !
Chapter 1: IntroductionChapter 1: Introduction
Significant Figures
Which digits count?
1. All significant digits in a number
Zeros...(a) ...between nonzero digits count(b) ...in the beginning of a number never count(c) ...at the end of a number....???
0.04305 4 sig figs
1.04305 6 sig figs
1.3 2 sig figs
4501 4 sig figs
Chapter 1: IntroductionChapter 1: Introduction
Significant Figures
2.036 g 2.03 g
4 significant figures 3 significant figures
Chapter 1: IntroductionChapter 1: Introduction
Significant Figures
2.036 g 2.030 g
4 significant figures 4 significant figures
Chapter 1: IntroductionChapter 1: Introduction
Significant Figures
If you don’t know where the number comes from, the number of significant figures is ambiguous:
51,000 mg
Chapter 1: IntroductionChapter 1: Introduction
Significant Figures
To eliminate ambiguity, express your number in scientific notation:
51,000 mg
5.1 x 10 mg4
5.1000 x 10 mg4
2 significant figures
5 significant figures
Chapter 1: IntroductionChapter 1: Introduction
Significant Figures
OK, but how many significant figures does the number 51,000 have?
51,000 mg
By convention (IUPAC):
51,000 mg =
Zeros...(c) ...at the end of a number do NOT count
5.1 x 10 mg42 significant figures