ANYTHING WITH MASS AND VOLUME

Matter

Pure Substances

Mixtures

Elements

Compounds

Homogeneous

Heterogeneous

Mixtures and Pure Substances

• Matter that consists of two or more substances mixed together but not chemically combined is called a mixture.

• A pure substance is made of only one kind of material and has definite properties.

Elements

• Elements are the simplest pure substance. – Examples: hydrogen, carbon,

and oxygen.

• The smallest particle of an element that has the properties of that element is called an atom.

Compounds• A molecule is formed when two or

more atoms combine.

• Compounds are pure substances that are made of more than one element bound together.– Examples: water, table salt, and

carbon dioxide.

MIXTURESHeterogeneous vs. Homogeneous

• Homogeneous matter: matter that has identical properties throughout. – Examples: Sugar, salt, water, and whipped

cream

• Heterogeneous matter: matter that has parts with different properties. – Examples: granite, soil, potpourri

Conservation

• Law of Conservation of Matter (Mass): matter cannot be created or destroyed.

• Law of Conservation of Energy: Energy cannot be created or destroyed; it may only change from one form to another.

Matter and energy MUST be conserved; it’s the LAW!

Virtually everything that is, is made up of atoms.

From the very large...

To the very small...

We are all made of atoms…and only atoms.

This includes you and me!

Making stuff nature

never dreamed of.

The Elements Song

Currently we have about 115 kinds of atoms. In the natural world there exists 88 different kinds of atoms.

The others have been artificially produced in laboratories.

We call each kind of atom an element, and give it a specific name and symbol.

Copper Cu

Gold Au

Periodic Table

Abundance of the elements,

by weight

The Earth’s interior is rich in iron

Sand is made of

Silicon & Oxygen

The ocean waters are

made of oxygen & hydrogen

Atoms are made up of protons, neutrons, and electrons.

Protons and neutrons are found in the nucleus of atoms -- roughly at the center

Electrons travel around the nucleus.

Of course real atoms don’t look anything

like this!

Different kinds of atoms, or elements, are different because they have different numbers of protons.

They don’t look anything like this either!

We list the elements by their atomic numbers - the number of protons

they have.

Hydrogen, number 1 Helium, number 2

Physical Properties

• Physical properties: characteristics that can be observed without changing the identity of the substance.

• Examples: – mass– volume– color – shape – texture– density

Physical Changes

• Physical change: a change in the physical form or properties of a substance that occurs without a change in composition.

• Examples:– melting– freezing– grinding– dissolving

Chemical Properties

• Chemical property: describes a substance’s ability to change into a different substance.

• Examples: – flammability– reactivity

Chemical Changes• Chemical change: occurs

when a substance changes composition by forming one or more new substances. (bonds are broken and bonds are formed)

• Example:– HCl + NaOH NaCl + H2O

Indications of a Chemical Change…

Flames

Gas is given off (not to be confused with boiling)

Color Change

Evaporation is a physical change

Breaking is a physical change.

Boiling is a change of state, and therefore a

physical change!

Rusting is a Chemical Change

Burning is a Chemical Change

Kinetic Theory

• All matter is made of atoms and molecules that act like tiny particles.

• These tiny particles are always in motion. The higher the temp., the faster the particles move.

• At the same temp., more massive (heavier) particles move slower than less massive (lighter) particles.

SOLIDS

• Definite shape?• YES

• Definite volume?• YES

• Molecules in a solid are tightly packed and constantly vibrating.

LIQUIDS

• Definite shape?• NO

• Definite volume?• YES

• Some liquids flow more easily than others. The resistance of a liquid to flow is called viscosity. – Honey has a high viscosity compared to water.

GASES

• Definite shape?• NO

• Definite volume?• NO

• The particles in a gas are spread very far apart, but can be compressed by pumping them into a restricted volume.

Phase Changes• Changes in phase are examples of

physical changes.

• Melting: solid liquid• Freezing: liquid solid• Vaporization: liquid gas• Condensation: gas liquid• Sublimation: solid gas

Changes of State

GAS

SOLID

Deposition

Sublimation

VaporizationCondensation

Melting

Freezing

LIQUID

Melting

• ENERGY is the ability to change or move matter.

• Energy is ABSORBED when substances melt or evaporate.– NOTE: our bodies cool down when our sweat

evaporates.

• Energy is RELEASED when substances freeze or condense.

Melting

• The change of state from solid to liquid.

• Energy (heat) is absorbed by the substance that is melting.

Freezing• The change of state from liquid to

solid. Opposite of melting. Energy (heat) is released by the substance undergoing freezing.

Evaporation• The change of state at the surface of a liquid as it passes to a vapor.

This results from the random motion of molecules that occasionally escape from the liquid surface. – Energy (heat) is released by the liquid (Cooling of the liquid results)

– Can happen at any temperature

Condensation

• The change of state from gas to liquid. The opposite of evaporation.– Energy (heat) is absorbed by the liquid (Warming of the

liquid results)

Boiling• Change from state from a liquid to a gas.• Occurs throughout the liquid.

– boiling point/temperature is determined by pressure

– Energy (heat) is released by the liquid.

*Boiling & freezing points depend on the pressure.*Boiling & freezing points depend on the pressure.

Water at normal pressure (1 atm):

• For water at normal (every day) pressures:

• Melting/freezing point:

• Condensing/boiling point:

0 oC (32oF)

100 oC (212oF)

Label the points & temperatures on your graph.

Change the pressure Change the Boiling Point

Phase Diagrams• a phase diagram shows the equilibria

pressure-temperature relationship among the different phases of a given substance

AB = AC = AD =

C

WATERWATER Carbon DioxideCarbon Dioxide

AB = AC = AD =

C

meltingcurve

AB = AC = AD =

C

meltingcurve

sublimationcurve

AB = AC = AD =

C

meltingcurve

sublimationcurve

vaporpressurecurve

triple point = Point ______The point at which all 3 phases of a substance (solid, liquid, gas) can coexist at equilibrium.

critical point = Point ______The combination of critical temperature and critical pressure.

A

C

D

critical temp = temp. above which a gas cannot be liquefied. (H2O=374ºC)

critical pressure = press. required to liquefy a gas at its critical temperature. (H2O=218 atm)

Conditions for H2O on other planets…