# Chapter 1 Matter and Measurement

```Chapter 1 Matter and Measurement
1. Classifications of Matter
Matter: anything that occupies space and has mass
We want to understand the macroscopic properties of
matter in terms of the microscopic properties of
individual atoms and molecules
2. States of matter
Physical states
Gas (g): no fixed volume/shape; compressible
Liquid (l) (distinct volume; assumes shape of its
container; not very compressible)
Solid (s) (distinct shape &amp; volume; rigid; not
compressible)
What can we conclude about the distance between
the particles in a solid v. a liquid v. a gas? What about
the speeds at which the particles move?
1
What determines whether matter will exist as a solid,
a liquid, or a gas?
Substances
A pure substance (or just a substance): matter that
has a fixed composition and distinct properties
Most forms of matter are mixtures of pure substances
Substances may be classified as either elements or
compounds
Elements
Cannot be decomposed into simpler substances by
chemical means
118 elements are currently known
Start learning the names and symbols of elements 154 (hydrogen – xenon)!
2
Compounds
Substances composed of two or more elements
united chemically in definite proportions by mass
e.g., H2O: a pure substance - has a constant ,
invariable composition (11% H, 89% O by mass),
regardless of its source
Law of Constant Composition (1800):
Elemental composition of a pure compound is always
the same
examples?
3. Properties of Matter
Two categories: chemical &amp; physical
Two types: intensive and extensive
3
Physical properties
can be measured without changing the basic identity
of the substance
e.g., color, density, melting and boiling points
Does measuring the boiling point of H2O change the
identity of this substance?
A physical change is a change in physical
appearance but not in the basic identity of the
substance
All changes of state (sl, l g, etc) are physical
changes
4
Chemical properties
Describe the way a substance may change or react to
form other substances
examples?
Chemical changes (or reactions)
Transform a substance into a chemically different
substance, e.g.,
C(g) + 2H2 (g)  CH4(g)
Is methane gas (CH4(g)) a chemically different
substance than C(g) and H2(g) ?
Intensive properties of matter
Do not depend on amount of material
examples?
5
Extensive properties
Do depend on amount of material
examples?
Mixtures
Combination of two or more substances, each of
which retains its own chemical identity
Two types of mixtures: heterogeneous and
homogeneous
Heterogeneous mixtures
don't have the same composition and properties
throughout
examples?
6
Homogeneous mixtures
Composition is uniform throughout
Also called solutions
examples?
Remember: in a mixture, each substance retains its own
chemical identity (i.e., physical and chemical properties)
Can we exploit this fact to gain information about and
separate the components of a mixture?
examples?
7
Problem du Jour
A solid white substance A is heated strongly in the
absence of air. It decomposes to form a new white
substance B and a gas C. The gas C has exactly the
same properties as the product obtained when
carbon is burned in an excess of oxygen.
What can we say about whether the solids A and B
and the gas C are elements or compounds?
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