Chapter 4.
Matter
Chemistry is the scientific discipline con-cerned with the characteristics, compo-sition, and transformations of matter.
Matter is anything that has mass and oc-cupies space.
States (Phases) of Matter
Properties of Matter
Properties are distinguishing characteristics used in identification and description.
Physical properties can be observed without changing the identity or composition of a substance.
Chemical properties describe the way a sub-stance changes or resists a change of iden-tity or composition into another substance.
Properties of Matter
Physical properties of water:
Colorless, odorless, liquid under normal con-ditions, boils at 100C, freezes at 0C, density is 1.00 g/mL.
Chemical properties of water:
Reacts with magnesium to form hydrogen gas and magnesium hydroxide.
Does not react with oxygen or nitrogen.
Changes in MatterPhysical changes are processes that
change the appearance of a substance but not its identity or composition.
Water boils to vapor or freezes to ice. Its composition is unchanged.
Chemical changes are processes that change the identity or composition of a substance.
Water reacts with magnesium. It is turned into hydrogen gas and hydroxide ions.
Properties of Matter
Intensive properties do not depend on the amount of substance present.
Examples:
Density, boiling point, freezing point, phase
Extensive properties depend on the amount of substance present.
Examples:
Mass, volume, energy content.
Classification of Matter
Matter
MixturesPure
Substances
Heterogeneous Homogeneous Compounds Elements
Classification of Matter
Classification of Matter
Classification of Matter
Classification of Matter
Classification of Matter
The Elements
An element is a pure substance that cannot be broken down into simpler pure substances using ordinary chemical means.
88 elements occur naturally.
~ 25 others have been produced.
Distribution of the Elements
Distribution of the Elements
Dicovery of the Elements
Number of Known Elements in Certain Years
0
20
40
60
80
100
120
-2500 -1500 -500 500 1500 2500
Year (BC, AD)
Nu
mb
er o
f Kn
ow
n
Ele
men
ts
Names and Symbols of Elements
A chemical symbol is a one- or two- letter abbreviation of an element's name.
The symbols are used as shorthand for the names in chemical communications.
The Periodic Table charts the elements by name and/or symbol, according to their properties.