Transcript Slide 1

PowerPoint to accompany
Chapter 1:
Part 1
Matter &
Measurements
Introduction:
Matter,
Measurement and
Molecules
Hubble
Image
Pillars of
Creation in
M16
Eagle
Nebula
A Starforming
region
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Chemistry
The study of matter and the
changes it undergoes.
Figure 1.2
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The Scientific Method
A systematic approach to solving problems
Figure 1.9
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Matter
Anything that has mass and takes up space.
Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia
Matter
Atoms are the building blocks of matter.
Each element is made of the same kind of atom.
A compound is made of two or more different kinds of
elements.
Figure 1.1
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Pure Substances, Elements
and Compounds
Pure Substance
Matter that has distinct properties and a composition
that doesn’t vary from sample to sample, e.g. salt.

Element
A substance that cannot be decomposed into simpler
substances, e.g. oxygen gas.

Compound
A substance that is composed of two or more different
elements, so it contains two or more different kinds of
atoms, e.g. water.

The elemental composition of a pure compound is always the same and this is known as the
Law of Constant Composition (or Law of Definite Proportions)
Joseph Proust (1754 - 1826)
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Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia
Solid Carbon Polymorphs
(different crystal structures, 1 element)
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Monatomic & Molecular Elements
Compounds and Mixtures
He
H2
BF3
All 3
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Mixtures

A mixture is a combination of two or more
substances in which each substance retains its
own chemical identity and can be separated
from each other.

There are two types:
- heterogeneous: a mixture which does not have
the same composition, properties and
appearance throughout: muesli, sand, rocks.
- homogeneous: a mixture which is uniform
throughout: solutions, air, smoke, alloys
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Banded Malachite
Cu2(CO3 )(OH)2
& Crystals
Copper Sulphate Hydrate &
Solution Cu(SO4) – 6H2O
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Classification of Matter
Figure 1.5
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Properties and
Changes of
Matter
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Properties of Matter

Physical Properties

Can be observed without changing a
substance into another substance.


Boiling point, density, mass, volume, etc.
Chemical Properties

Can only be observed when a substance is
changed into another substance.

Flammability, corrosiveness, reactivity with acid,
etc.
Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia
Properties of Matter

Intensive Properties

Independent of the amount of the substance
that is present.


Density, boiling point, colour, etc.
Extensive Properties

Dependent upon the amount of the
substance present.

Mass, volume, energy, etc.
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GaAs a semi-conductor has nearly
overlapping molecular bonds
Being a semi-conductor
is an intrinsic property
of this compound, due
to its bonds & crystal
structure.
Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia
Changes of Matter

Physical Changes

Changes in matter that do not change the
composition of a substance.


Changes of state, temperature, volume, etc.
Chemical Changes

Changes that result in new substances.

Combustion, oxidation, decomposition, etc.
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Chemical Reactions
(Chemical Change)
Figure 1.6
In the course of a chemical reaction, the reacting
substances are converted to new substances.
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Compounds
Compounds can be broken down into more
elemental particles; for example, during the
electrolysis of water, the smaller particles
hydrogen gas and oxygen gas are created.
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2H2(g) + O2 (g)  H2O (g) + E
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Separation of Mixtures
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Separation of Mixtures
1. Distillation
Separates a
homogeneous
mixture on the
basis of differences
in boiling point.
Figure 1.8
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Separation of Mixtures
2. Filtration
Separates solid substances from liquids and solutions.
Figure 1.7
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Units of Measurement
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SI Units


Système International d’Unités
Uses a different base unit for each quantity
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Metric System
Prefixes convert the base units into units that
are appropriate for the item being measured.
Table 1.3
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SI Units - Length and Mass

The SI base unit of length is the metre
(m).

Mass (m) is a measure of the amount of
material in an object. The SI base unit of
mass is the kilogram (kg).
Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia
SI Units - Temperature




The Kelvin is the SI
unit of temperature.
It is based on the
properties of gases.
There are no negative
Kelvin temperatures.
K = C + 273.15
Figure 1.10
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Derived SI Units Volume

The most commonly
used metric units for
volume are the litre
(L) and the millilitre
(mL).


A litre is a cube 1 dm
long on each side.
A millilitre is a cube 1
cm long on each side.
Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia
Derived SI Units Density
Density is a physical property of a substance
and is determined through the following
formula:
mass
density = volume
or symbolically
m
= V
Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia
Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia
Uncertainty in
Measurement
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Uncertainty in Measurements
Different measuring devices have different
uses and different degrees of accuracy.
Figure 1.12
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Significant Figures

All digits of a measured quantity,
including the uncertain, are called
significant figures.

The greater the number of significant
figures, the greater the certainty of the
measurement.
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Significant Figures

All nonzero digits are significant, e.g. 123.45

Zeros between two significant figures are
themselves significant, e.g. 103.405

Zeros at the beginning of a number are
never significant, e.g. 00123.45 = 123.45

Zeros at the end of a number are
significant if a decimal point is written in the
number, e.g. 123.450 has six significant figures but 123450 has
only five significant figures
Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia
Significant Figures

When addition or subtraction is
performed, answers are rounded to the
least significant decimal place.

When multiplication or division is
performed, answers are rounded to the
number of digits that corresponds to the
least number of significant figures in any
of the numbers used in the calculation.
Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia
Precision and Accuracy

Accuracy refers to the proximity of a measurement
to the true value of a quantity.

Precision refers to the proximity of several
measurements to each other.
Figure 1.15
Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia
Reading Errors & Interpolation
27°+/- 1°C
Brown, LeMay, Bursten, Murphy, Langford, Sagatys: Chemistry 2e © 2010 Pearson Australia