The Science of Chemistry

The Science of Chemistry

Before chemistry there was…..

Alchemy

Alchemy:A medieval science and philosophy

aiming to achieve:

1. Transmutation of base metals (like lead) into gold

Alchemy

2. Discovery of a universal cure for disease

Alchemy

3. Discovery of a way to prolong life

Has modern science achieved these things?

Wealth for all?

Cure for disease?

Prolonged life?

Why is Gold valuable?

• Rare

• Pretty

• Soft, easy to shape

• Resists corrosion

• Chemically unreactive

The science that studies the

structure,

composition,

and properties

of substances

and their transformations

(Webster)

What are the simplest substances?

• The ELEMENTS ( only about 90 occur naturally, 114 discovered)

• Listed in the Periodical Table

• Basic building blocks for all other more complex substances (compounds) found in the universe

Abundance of common elements in the Universe

• 60% Hydrogen H element #1

• 37% Helium He element #2

• 3% elements # 3-90

Abundance of elements on Earth (crust and atmosphere)

• 35% iron

• 30 % oxygen

• 15 % silicon

• 13% Magnesium

• 2.4% nickel

• 4.6% others

Origin of the Elements

Big Bang

• 15-20 billion years ago• Matter and energy scatter, expand, and

cool• Matter condenses to form galaxies,

Element Hydrogen forms• Stars form in galaxies. In stars, H fuses to

form Helium and energy• More fusion allows heavier elements to

form

We are all star dust……

Matter

Anything that has mass and takes up space (volume)

What is NOT matter???

Classification of Matter

Matter

Can it be separated by physical means?

If yes….

Then you have a Mixture

Physical ways to separate a mixture

• Filtering

(particle size)

• Distillation

(boiling point)

(dissolved solid)

Physical ways to separate a mixture

• Chromatography

(attraction to paper)

Is the mixture uniform throughout?

• IF yes, it is HOMOGENEOUS

If no, then the mixture is Heterogeneous

Homogeneous vs. Heterogeneous mixtures

MatterCan it be separated by physical means?

MixtureIs it uniform throughout?

Substance

HomogeneousGatoradeBronzeBrass

Homogenized beverages

HeterogeneousDirt

Sea shellsRocky road ice cream

Non-homogenized beverages

YES NO

YES NO

If matter can NOT be separated by physical means….

It is a SUBSTANCE

If the substance can’t be broken down, it is an ELEMENT

Elements are made of only one type of atom

Ex. Aluminum, carbon, oxygen

SUBSTANCEIf the substance CAN be broken down, it is a

COMPOUND, made of two or more different kinds of atoms chemically bonded together.

Ex. Water (2 Hydrogens and 1 oxygen)

MatterCan it be separated by physical means?

MIXTUREIs it uniform throughout?

SUBSTANCECan it be broken down?

HomogeneousGatoradeBronzeBrass

Homogenized beverages

HeterogeneousDirt

Sea shellsRocky road ice cream

Non-homogenized beverages

COMPOUNDWATER H20SALT NaCl

ELEMENTAluminum

Graphite (Carbon)

YES NO

YES NO Yes NO

ELEMENTS can be….

• MONATOMIC : single atoms Al

• DIATOMIC : two of the same atom bonded together in pairs O2

• POLYATOMIC: three or more of the same atom bonded together O3

7 Diatomic Elements

Particles of Matter

Review

What is……

MATTER

SUBSTANCE

MIXTURE

ELEMENT

COMPOUND

HETEROGENEOUS VS. HOMOGENEOUS

CHEMISTRY: THE STUDY OF MATTER

Did you know that……..

One of the most popular “foods” in the United States is an entirely SYNTHETIC (man-made) mixture.

Can you guess what it is?

SODA

The average person consumes 40 GALLONS (!)

of soda each year

Mixture:carbonated watersweetener, acids,flavorings, caffeine

States of Matter

GAS LIQUID SOLID

Physical Properties of Matter

The properties of a substance that can be demonstrated without changing the

composition of the substance

Size (length, volume)

Density

Mass

Color

Physical Properties

Melting Point

Ex. Ice (solid water) starts to melt to liquid water at 0 degrees Celsius

Boiling Point

Ex. Water boils into steam at 100 degrees Celsius

Physical Properties

Malleability: can be pounded into a new shape without breaking

Metals are malleable

Physical Properties

Iron is malleable

Fe

Physical Properties

Ductility

Can be pulled into long wires without breaking

Metals are ductile

Physical Properties

Crystal Shape

Reflects the regular arrangement of atoms in the solid

Physical ChangeA change in the sample of matter that does

not result in a NEW substance:

Phase Changes

Changes in shapeSolid liquid gas

Chemical Properties of Matter

How matter behaves when it changes into a NEW substance.

EX. Iron rusts silver tarnishes

Milk sours sugar ferments

eggs rot leaves turn

paper burns

Chemical Change

Substance changes into a NEW substance.

This change is often an irreversible and permanent change in composition

Burning

Tarnishing

Rusting

Oxidizing

Chemical Reaction

Chemical changes mean a chemical reaction has occurred

REACTANTS PRODUCTSold substances become new substances

Sodium + Chlorine sodium chloride (table salt)

Na + CL NaCL

Test Review

• Know names and symbols of common elements

Name SymbolAs SodiumCa IronMn TinCu GoldK Lead

Test Review

Matter

Classify the following samples of matter





Classify the following samples:

Classify the particles of matter

Identify the following changes as Physical or Chemical





Fe



Periodic Table Review

1. Elements are arranged according to______

2. Vertical columns are called________3. Horizontal rows are called ________4. There are ______ periods in the table5. Most elements are classified as _____6. Where are the transition metals?7. What are the metalloids?

Periodic Table Review

1. Describe 3 properties of metals

2. Describe 2 properties of non metals

3. Group 2 metals are called____________

4. Group 17 non metals are called _______

5. What two elements are liquid at room temperature?

6. How can you tell if a compound contains a transition metal?

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The Science of Chemistry