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away.• Grab your notebook

Chemistry

The study of matter

Matter

• Anything with mass that takes up space.

Density = Mass/volume(space)

Density is a physical property used to identify matter.

Classification of matter-This is done using both chemical and physical properties of the substances.

Element (Ele)

Compound (Cpd)

Mixtures (Mix.)

Elements• Made of only 1 type of atom• Homogeneous-uniform throughout• 118 currently known to exist• Represented by symbols taken from the

Latin names• Classified into

– Metals– Nonmetals– Metalloids

Metals

• True metals• Shiny/luster• Soft• Silver or grey• Conducts electricity/heat• Malleable/ductile• HighTensile strength• Very reactive

• Transitional metals• Same characteristics as true metals but to a

lesser degree.• Two have color-Copper and Gold.• Cpds of these ele. are very colorful.

Nonmetals

• Solids, liquid, and gases• Those that are solids are very brittle• Do not conduct heat/electricity (insulators)• Special type of nonmetal are the noble

gases– Nonreactive or inert.

Metalloids

• These are located on the staircase• Metalloids have characteristics of both

metals and nonmetals– Example Silicon is very brittle but will conduct

electricity.

A property of all elements

• One characteristic that all elements have in common is that they cannot be decomposed by ordinary chemical means. They can’t be broken down into simpler substances.

Compounds

• Consist of 2 or more different elements chemically bonded together

• When bonded the elements lose their physical/chemical properties and they form new properties.

• Infinite number of cpds• Composition of these elements within a

compound is always constant

Compounds

• Represented by formulas CaCO3 H2O2

• Classified as– Organic-– Inorganic-

Organic cpds

• Organic cpds are hydrocarbons-• These cpds come from living or once living

things– Wood– Wool– Petroleum– Plastic

Inorganic cpds

• Inorganic cpds do not contain Hydrogen and carbon together in its formula– Salt NaCl– Sand SiO2

-Water H2O

Mixtures (Not a pure substance)

• Homogeneous• Uniform throughout• Looks like a pure substance• All homogeneous mixtures are called

solutions– Saline– Air– Alloys

• Heterogeneous• Nonuniform throughout• Can see the parts of the mixture• Examples

– quartz– smog– Italian salad dressing

Mixtures

• Do not have constant compositions• Each component of the mixture retains its

own identity and keeps their properties• Can be separated using physical methods

Physical Properties

• Uses the five senses– Touch, taste, smell, etc

• The measuring of a physical property does not change the substances identity.

Physical properties

• Extensive properties depend on the amount of substance– Mass,Volume,Shape

• Intensive properties do not depend on the amount of substance– Color, phase ,melting pt, boiling pt, density etc

Chemical Properties• Describe how the substance behaves or

reacts with other substances and in the process will change the identity of the substance.– Does it burn?– Does it oxidize or rust?– Does it react with X?– (Chemical Properties always involve chemical

changes.)

Physical and Chemical Changes

• Physical: any change in a physical property that retains the substances identity

• Chemical: any change in a substance that brings about a change in the substances identity

You can tell this if the – color changes– a gas if formed– the temp. changes– or a precipitate (ppt) is created.

Recap

• Physical Properties• Describe what a

substance is like.

• Chemical Properties• Describe how a

substance behaves or reacts.

• Always accompanied by– Color change, temp.

change, gas forming or , ppt.

Changes

• Physical changes involve a change in some aspect of the substance WITHOUT changing what it is

• Chemical changes always involve a change in what the substance is.

• Evidence…– Color change– Temp change– Gas forms– Ppt.