Chemistry – Matter Unit

• What is matter?

• What is

chemistry?

• What is the

organization of

matter?

• What is the

nature of matter?

Is Air matter?

• What are the two criteria for matter?

–Does it take up space?

–Does it have mass?

What is chemistry?

• “Chemistry is the study of the composition, structure, and the properties of matter and the changes it undergoes.”

What is the composition of matter?

Matter

Pure Matter

SubstanceImpure Matter

Mixture

What is a pure substance?

• A pure substance has a definite composition (proportion).

• The composition of a substance will have the same percent of elements no matter where the sample was obtained.

– Water from Lake Okechobee and water from the Atlantic Ocean (once cleaned up) will have the same composition of hydrogen to oxygen.

– Gold is the same as other gold (once cleaned up).

What is a pure substance?

• A pure

substance, by

definition, is an

element or a

compound.

• A container with

an almost pure

compound:

Pure Substance

Pure Substance

Element Compound

What is an element?

• “a pure substance made of only one kind

of atom”

• A substance that cannot be decomposed

any farther by simple chemical means

• An element has a definite composition.

Gold from South Africa is the same, when

purified, as a sample from California.

Periodic Table of Elements

• Most elements on the periodic chart are metals.

• Elements past 110 have been discovered and made but

are unstable

Elemental Samples

• Zinc, copper, lead, carbon, sulfur

What is a compound?

• “A compound is a substance

that is made from the atoms of

two or more elements that are

chemically bonded.”

• The definition is actually more

involved than this.

What is a compound?

• A compound is a substance that

cannot be decomposed any farther by

simple physical means.

• A compound has a definite

composition by mass.

• A compound is made up of two or

more elements chemically combined.

What is a compound?

• A compound no longer has the

properties of its constituent

elements.

• Table salt, NaCl or sodium

chloride, is a compound of the

element sodium and the element

chlorine.

Sodium

Sodium metal

• Soft, can be

cut with a knife

• Shiny

• Good

conductor of

electricity

• Very reactive

Sodium in water

Chlorine gas

Chlorine gas

• Greenish gas

• Poisonous

• Heavier than

air

Sodium in chlorine gas

Sodium chloride, NaCl

• Sodium chloride dissolves in water

rather than reacts with water.

• Sodium chloride is a white solid, not a

poisonous green gas.

• Sodium chloride is its own substance

with its own properties, not those of

either sodium or chlorine.

Samples of Other Compounds

• Sucrose (table sugar), Sodium Chloride, Water, Copper(II) sulfate

Colored Compounds

• Cobalt(II) chloride, Iron(II) sulfate, Potassium dichromate, Potassium chromate, Nickel(II)

nitrate, copper(II) sulfate

What is the composition of

matter?Matter

Pure Substance Impure Matter

Mixture

Impure Matter - Mixture

• “A mixture is a blend of two or

more kinds of matter, each of

which retains its own identity and

properties.”

• A mixture is made up of two or

more substances that are not

chemically combined.

Mixtures

• Mixtures can be separated by simple

physical means.

• Two mixtures containing the same

substances may not have the same

proportions.

• Example: Very salty water versus

barely salty water. Very sweet sugar

water versus slightly sweet sugar

water.

Water and Dye Mixture

• Two mixtures of the same substances may

have different proportions.

Mixtures

Mixtures

Homogeneous

Mixture

Heterogeneous

Mixture

Solutions

• Mixtures

– Mixture = a blend of two or more kinds of

matter, each of which retains its own

identity and properties

a) homogeneous mixture = a mixture that

is uniform in composition throughout

Ex: Food coloring and water

b) heterogeneous mixture = a mixture that

is NOT uniform in composition throughout

Ex: Oil and water

Heterogeneous Mixtures

• Sand and water on the left and sand and

gravel on the right.

THE NATURE OF SOLUTIONS:

1) Solvent = the substance that does the dissolving in a solution

a) Typically present in the greatest amount

b) Typically a liquid

c) Water is the most common or “universal” solvent

2) Solute = substance being dissolved in a solution

a) Typically present in the least amount

b) Typically a solid

Chemical Separation Methods

• Heat the compound.

Chemical Separation Methods

• Use Electrolysis

which is using an

electric current to

decompose the

compound.

• An electrolyte has

been added to the

water since water

does not conduct.

Mixtures

• How can mixtures be separated?

–Use Physical Separation

Methods.

What are examples of physical

separation methods?

Physical Separation Methods

• Distillation is the

separation of

mixtures by using

the difference in

boiling points of

liquids.

• A water cooled

condenser is used.

Physical Separation Methods

• Filtration uses

the difference in

particle size to

separate

mixtures.

• Filter papers

have different

size pores.

Physical Separation Methods

• Chromatography

uses the difference

in solubility in

various solvents.

• Gas, liquid, thin

layer, and paper

chromatography

are widely used.

States of Matter

• Three states of matter:

• Liquid, solid, gas

Physical Changes

• During physical changes matter

changes in appearance without

forming new substances.

• What some examples of physical

changes?

Physical Change Examples

• Breaking or tearing

Physical Change Examples

• Boiling or condensing

Physical Change Examples

• Freezing or melting

Physical Change Examples

• Sublimation

Physical Change Examples

• Sublimation:

• “The change of state directly to a gas

is known as sublimation.”

• “The reverse process is called

deposition, the change of state from

a gas directly to a solid.”

Chemical Changes

• During chemical changes new

substances are formed with

different properties than the

original substances.

• What is an example of a chemical

change?

Chemical Change Example

• Heating baking soda, sodium hydrogen

carbonate, forms sodium carbonate,

carbon dioxide, and water. The formation

of carbon dioxide is what causes cakes to

rise.

Mixture or Pure Substance

• These bottles contain sodium chloride,

sucrose, and a mixture of the two. Which

is which and how can they be identified?

Physical and Chemical

Properties

• What are some physical propertiesof this pen?

Physical Properties

• Examples:

–Color

–Hardness

–Texture

–Volume

–Length

–Mass

Physical Properties

• More Examples:

–Density (mass/volume ratio)

–Odor

–Sound

–Boiling point

–Melting point

–Magnetism

Physical Properties

• Melting Point and freezing point temperatures are the same.

Chemical Properties• A chemical

property is how something reacts.

• Does the pen float

• Physical

• Does the pen dissolve

• Physical

• Does the pen react with water

• chemical.

Chemical Properties

• Does the pen burn

• chemical property.

• Whether and how something reacts

• chemical.

Extensive vs Intensive

• Extensive Properties depend upon

the amount of matter that is present.

• Intensive Properties do not depend

on the amount of matter present.

These properties are the same for a

given substance regardless of how

much of the substance is present.

Periodic Table

The horizontal rows of the periodic table are called PERIODS.

The vertical columns of the periodic table are called GROUPS, or FAMILIES.

The elements in any groupof the periodic table havesimilar physical and chemicalproperties!

silicon

Metals:

The noble gases are colorless, odorless, tasteless, and

nonflammable under standard conditions. They are also

sometimes called the "inert gasses" due to their lack of

reactivity with other chemicals.

Non-Metals

Non-metals are not able to conduct electricity or heat very well,

are very brittle, and cannot be rolled into wires or pounded into

sheets. The non-metals exist in two of the three states of

matter at room temperature: gases (such as oxygen) and

solids (such as carbon). The non-metals have no metallic

luster, and do not reflect light

Metalloids:

Metalloids are the elements found along the stair-step line that

separates metals from non-metals. Some of the metalloids, such as

silicon and germanium, are semi-conductors. This means that they can

carry an electrical charge under specific conditions. This property

makes metalloids useful in computers and calculators microchips.

Nobel Gases:

Metalloids are the elements found along the stair-step line that

separates metals from non-metals. Some of the metalloids, such as

silicon and germanium, are semi-conductors. This means that they can

carry an electrical charge under specific conditions. This property

makes metalloids useful in computers and calculators microchips.