CH1120 The Nature

of Chemistry

Chemistry The science that seeks to understand

what matter does by studying

what atoms and molecules do.

Chemistry The Study of Matter

and the Changes That Matter Undergoes

Matter

Anything That Has Mass and Occupies Space

Solid: Particles are close together and vibrate about a fixed point.

Sample shows definite volume and shape.

Incompressible.

Liquid: Particles are close together and are free to move relative to one another. Sample

shows definite volume but indefinite shape.

Incompressible.

Gas: Particles are far apart and are free to move relative to one

another. Sample shows indefinite volume and shape. Compressible.

States of Matter

Solid State Gaseous

State

Liquid State

States of Matter

Pure Substances Elements - The Simplest Form of Matter

Basic Building Blocks of Matter

Compounds- Formed from Chemical Combination of Elements

Mixtures Homogeneous Mixture - Identical Composition Throughout

Heterogeneous Mixture - Composition Not Identical Throughout

Classification of Matter According to Its Composition

Classification of Matter

Uniform composition throughout

Classification of Matter

Classification of Matter According to Its Composition

carbon dioxide molecule

water molecule

Example: NaCl

113

Nh112

Cn111

Rg110

Ds114

Fl115

Mc116

Lv117

Ts118

Og

Atomic Element

MolecularCompound

Which class of matter is represented by these pictures?

MolecularCompounds

Which class of matter is represented by these pictures?

HeterogeneousMixture

HomogeneousMixture

Which class of matter is represented by these pictures?

HomogeneousMixture

?

Changes of Matter

Physical Changes Chemical Changes

Changes of Matter

Physical Changes

Produce the Same Substance in a Different State

Solid <-------------------> Liquid <------------------> Gas

Melting, Freezing, Vaporization, Condensation, Sublimation, Deposition

Physical Properties

Characterize the Physical State and Behavior of a Substance Melting point, boiling point, color, odor, taste

melting

freezing

vaporization

condensation

subl

imat

ion

depo

siti

on

Physical Changes of Matter

Physical Changes of Matter

Separating Mixtures through Physical Changes “Distillation”

Separating Mixtures through Physical Changes

“Filtration”

Changes of Matter

Chemical Transformations New Substances Formed from Starting Substances

Reactants <--------------------> Products

Chemical Properties

Observed When a Pure Substance is Transformed into Other Pure Substances

Physical vs Chemical Changes

Physical change: Solid water becomes liquid water. The composition does not change and the particles are the same.

Physical vs Chemical Changes

Chemical change: Electric current decomposes water into different substance (hydrogen and oxygen). The composition

changes and the particles are different.

Vaporization: a physical change

Push the button on a lighter without turning the flint.

The liquid butane vaporizes to gaseous butane.

The liquid butane and the

gaseous butane are both composed of butane molecules.

This is a physical change.

 Burning: a chemical change

Push the button and turn the flint to create a spark.

Produce a flame. The butane molecules react with

oxygen molecules in air to form new molecules, carbon dioxide and water.

This is a chemical change.

Conservation of Mass: There Is No New Matter

Pure substanceWhen heated and

cooledWhen subjected to

electric current

Mercuric oxide(a red solid)

Produces a black solid and a colorless gas

Produces a black solid and a colorless gas

Sodium Chloride(a white solid)

Melts and solidifies to the same solid

Produces a shiny metallic substance and a green gas

Iodine(a purple solid)

Sublimes and crystallizes to the same solid

No change

Water(a colorless liquid)

Evaporates and condenses to the same liquid

Decomposes to two gases in a 1:2 ratio

Mercury(a shiny liquid)

Evaporates and condenses to the same liquid No change

Helium(a colorless gas)

No change No change

Effects of “Experiments” on Pure Substances