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.