Chemistry - Matter Unit · 3) solution equilibrium = state where the solute is dissolving at the...

Chemistry – Matter Unit

• What is matter?

• What is

chemistry?

• What is the

organization of

matter?

• What is the

nature of matter?

What is NOT Matter?

Energy !

Types of Energies

• Mechanical

• Chemical

• Heat

• Atomic

• Light

• Electrical

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.”

• All chemical reactions involve energy.

What is the composition of matter?

Matter

Pure Matter

Substance Impure 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 through 114 but not 113 have been discovered

or made.

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.

Heterogeneous Mixture

Types of Mixtures:

1) solution = a homogeneous mixture

2) suspension = a mixture in which the particles are so

large that they settle out unless the mixture is constantly

stirred or agitated

Heterogeneous mixture

Ex: Sand and water

3) colloid = a mixture consisting of particles that are

intermediate in size between those in solutions and those in suspensions

Heterogeneous mixture

Ex: Milk

Colloidal Suspension

• Fog

Tyndall Effect

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

9 Possible Solution

Combinations:

Factors Affecting the Rate of Dissolving

(Increase Solution Rate):

• 1) Grinding: increases surface area

• 2) Stirring: allows solvent continual contact with solute

• 3) Heating: increases kinetic energy; increases mixing

SOLUBILITY: 1) Solubility = quantity of solute that will dissolve in specific

amount of solvent at a certain temperature.

(pressure must also be specified for gases).

a) Ex: 204 g of sugar will dissolve in 100 g of water at 20°C

b) soluble and insoluble are relative terms

c) solubility should NOT be confused with the rate at which

a substance dissolves

2) saturated solution = a stable solution in which the

maximum amount of solute has been dissolved.

3) solution equilibrium = state where the solute is dissolving at the

same rate that the solute is coming out of solution (crystallizing).

a) Opposing processes of the dissolving and crystallizing of a solute

occur at equal rates.

b) solute + solvent solution

4) unsaturated solution = a solution that

contains less solute than a saturated

solution under existing conditions

5) supersaturated solution = a solution that

temporarily contains more than the

saturation amount of solute than the

solvent can hold (unstable)

3 FACTORS EFFECTING SOLUBILITY:

The extent to which a given solute dissolves in a

solvent depends on the identity of the solute and

solvent and also on the existing conditions of

pressure & temperature 1) Nature of solute

and solvent

a)“Like dissolves

like” = rule of

thumb for

predicting whether

or not one

substance

dissolves in

another

• “Alikeness”

depends on:

o Intermolecular

forces

o Type of

bonding

o Polarity or

nonpolarity of

molecules:

ionic solutes

tend to dissolve in polar

solvents but not

in nonpolar solvents

Solvent-Solute Combinations:

2) Pressure:

a)Pressure has little effect on the

solubility of liquids or solids in liquid

solvents.

b)The solubility of a gas in a liquid

solvent

INCREASES when pressure

increases. It is a direct relationship.

3) Temperature:

a)The solubility of a gas in a liquid

solvent DECREASES with an increase

in temperature.

b)The solubility of a solid in a liquid

solvent MOST OFTEN increases with an

increase in temperature. However,

solubility changes vary widely with

temperature changes

sometimes decreasing with temperature increases.

Mixtures vs. Compounds

• Rocks are mixtures.

• Minerals are pure substances

• Granite rock

Mixtures vs Compounds

• Minerals are

pure substances

although many

have impuities

that must be

cleaned up first.

Minerals

Amethyst

Halite

Diamond

What is the nature of matter?

• An atom is the smallest unit of an element that maintains the properties of that element

– An atom is made up of electrons, protons, and neutrons as well as other particles.

• Protons and neutrons are made up of quarks.

What is the nature of matter?

• A molecule is a unit

that consists of more

than one atom

bonded together.

• A molecule can have

atoms of the same

element such as

oxygen. These are

called diatomic

elements.

2O

Blue – diatomic

elements

Diatomic elements – blue

Tetraatomic element – red

Octatomic element - yellow

What is the nature of mature?

• A molecule can

have atoms of

more than one

type of element.

• Water

• Sugar (sucrose)

OH2

112212 OHC

Atoms and Molecules

• Three particles:

– 2 atoms of hydrogen

– 1 atom of oxygen

• One particle:

– 1 molecule of water

Atoms

• How can an atom of an element be broken up into atoms of other elements or into other smaller particles and energy?

• Nuclear Reaction

Compound

• How is a compound broken up into its

elements or other simpler compounds?

–Use a chemical separation

method.

• What are some examples of chemical

separation methods?

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.


• Filtration uses

the difference in

particle size to

separate

mixtures.

• Filter papers

have different

size pores.


• 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


• Boiling or condensing


• Freezing or melting


• Sublimation


• 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 properties of 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 is physical.

• Does the pen dissolve is physical.

• Does the pen react with water is chemical.

Chemical Properties

• Does the pen burn is a chemical property.

• Whether and how something reacts is 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.

Extensive vs Intensive

• Which of the properties listed

earlier are extensive and which

are intensive?

• Comparisons of several

properties are used together to

identify an unknown.

Matter Unit

Now it is time to try “Chemistry Vocabulary

Worksheet: Application of Matter”.

.

Chemistry Vocabulary

• A Symbol is a

representation of

an element.

• One or two letters

may be used.

• The first letter is

upper case while

the second is lower

case.

H C O

Fe Cl Ag

Cu Ba Cf


• A formula is a

representation of

a molecule of an

element or a

molecule of a

compound. 42

2

SOH

O


112212 OHC

• The subscript

represents the

number of

atoms of a

particular

element in the

molecule.

12 atoms of carbon

22 atoms of

hydrogen

11 atoms of oxygen


42SOH

• If no subscript

is shown. An

understood

one is

indicated.

2 atoms of hydrogen

1 atom of sulfur

4 atoms of oxygen


• A coefficient is a

number in front of

a formula and

represents the

number of

molecules.

• If no coefficient is

shown, one

molecule is

indicated.

112212 OH2C

2 molecules of sucrose

24 atoms of carbon

44 atoms of hydrogen

22 atoms of oxygen


wateroxygen Hydrogen

22 222

OHOH

• An equation is a sentence showing what is happening in a chemical

reaction.


O2H2 222 OH

• The reactants are the substances

(elements or compounds) that will

react. They are on the left or starting

side.


OH222 2O 2H

• The products on the right side of the equation are what are formed or are produced during the reaction.


• An atom is the smallest unit of an element that maintains the properties of that element

– An atom is made up of electrons, protons, and neutrons as well as other particles.

• Protons and neutrons are made up of quarks.


• A atom is made up of a nucleus and

particles outside the nucleus called

electrons.

• Electrons are negatively charged

particles.

• The mass of an electron is about

1800 times smaller than that of the

proton and neutron.


• The nucleus is the tiny positive core of the atom.

• Two of the particles in the nucleus are the proton and the neutron.

• The proton is a positively charged particle.


• What is wrong with this commonly used picture?

• The nucleus is 1/10000 times smaller than the atom.

• The atom is mostly empty space.


• Proton: – The charge on a proton is equal in

magnitude but opposite in sign to the charge on an electron.

• A proton is made up of three quarks.

– Two quarks have a +2/3 charge.

– One quark has a -1/3 charge.


• The mass of a proton is approximately

1800 times heavier than an electron.

• ***The number of protons present

is what determines the type of

atom.***

– If the number of protons change, an

atom of a different element is formed.


• The number of protons found in the nucleus is known as the atomic number.

–Hydrogen with an atomic number of 1 has only one proton. If it had 2, it would be helium.

–Uranium with an atomic number of 92 has 92 protons.


• A neutron is an uncharged particle

found in the nucleus.

• The mass of a neutron is almost the

same as the mass of a proton.

• A neutron is made of three quarks.

– One quark has a +2/3 charge.

– Two quarks have a -1/3 charge.


• Two atoms of the same element can

have differing numbers of neutrons.

These are called isotopes.

• Hydrogen has three isotopes:

– Hydrogen with 1 proton and 0 neutrons

– Deuterium with 1 proton and 1 neutron

– Tritium with 1 proton and 2 neutrons


• The different masses of these

isotopes give them different

properties such as melting and boiling

points and reactivities and stabilities.

• Regular uranium is not radioactive

enough for a nuclear fuel. Only

certain isotopes of uranium will work.


• The mass number is the total

number of protons and neutrons in

the nucleus of the atom.

• The mass number is not found on the

periodic table.

• The masses on the table are the

weighted averages of the isotopes.


Particle Symbol Charge Mass

Number

Electron 1- 0

Proton 1+ 1

Neutron 0 1

p

-e

0n


• Nuclear Symbol:

• Mass Number

– Number of protons and neutrons

• Atomic number

– Number of protons

– Found on Periodic Table

U235

92


• Number of protons =

• 17

• Number of neutrons =

• 18

• Number of electrons=

• 17

• The number of

protons = number of

electrons

Cl35

17


Mg25

12


• 12


• 13


• 12


• In a neutral atom the number of

protons is equal to the number of

electrons.

• The number of protons can never

vary in an atom.

• The electrons are the particles that

can be gained or lost in a reaction.


• The sum of the positive protons and the negative electrons give the overall charge of the atom.

• The term charge was once called valence.

• The charge is shown as a superscript to the upper right.

2Mg



• 17


• 19


• 18

• (17+) + (?-) = 1-

– So ? = 18-

-36

17Cl



• 12


• 12


• 10

• (12+) + (?-) = 2+

– ?- = 10

224

12Mg


• An ion is a charged atom or group of

atoms.

• A cation is a positively charged ion.

• An anion is a negatively charged ion.

The prefix an- can mean not or

negative.


• Free state – The atom or molecule is not combined with atoms of other elements.

– Gold can be found in the free state.

– Because of its reactivity, sodium cannot.

• Combined state – The atom is part of a compound.

Matter Unit

• Now it is time to try “Chemistry Vocabulary

Worksheet: Application of Matter”.

• The exam will cover the material in this

unit, the lab safety material, and the lab

drawer equipment.

• Know the examples and how the ideas go

together. Know all parts of the definitions.

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Chemistry - Matter Unit · 3) solution equilibrium = state where the solute is dissolving at the...

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