1

Studying All That Matters

I thought that I would never see a class as hard as chemistryWith all the thoughts that chemists had, I‘m sure that they

were driven mad!

But oh, the things I‘ve slowly learned—from halogens to oil burned.

At first the periodic table seemed quite a task; I was not able!It was too much, and I confess—when exam time came, I blew

the test.

But as I learned, the more I saw that chemistry explains it all.Why make-up runs! Why acid rain! How toast is burnt! Why

plugged up drain!How iron rusts and sodas fizz! I know so much—I‘m now a

whiz!So I will sing its praises true. Oh, chemistry, how I love you!

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Classification of Matter

Matter is anything that has mass (inertia) and occupies space.

Heterogeneous matter – different parts have different properties

Homogeneous matter – has similar consistency throughout

Homogeneous mixtures – solutions

Pure substances – compounds and elements

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Dalton’s Atomic Theory

All elements are composed of tiny indivisible particles called atoms NWK: atoms are divisible

All matter is composed of combinations of these atoms

Atoms of the same element are identical and atoms of different elements are different NWK: isotopes of the same element are

different

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A POEM

Matter, matter everywhere,

But what are we to think?

What it is all composed of,

Is essentially the link!

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Models of the Atom

Chocolate-Chip Ice Cream Model Also called plum pudding model – J. J. Thompson Ice cream is the proton sea chips are electrons

Rutherford Model (Thompson‘s student) Atom mostly empty space – nucleus in center and

electrons in orbit

Bohr Model Electrons orbit in shells, do not have to stay in the same

shell all the time (move up/down and absorb/give off energy)

Quantum Mechanical Model Mathematical model based on probability of where

electrons are at any given time Electrons within shells behave differently (have s, p, d

orbitals)

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Parts of the Atom

Protons – positively charged (+) Determine how atom will behave (because number

of protons never changes) Atomic number = number of protons Found in nucleus

Neutrons – no charge Found in nucleus Weigh about the same as protons Different amounts indicate different isomers (some

isotopes are radioactive, some are not)

Electrons – negatively charged (-1) Tiny (weigh only 1/1860th of proton) Orbit nucleus May be lost or gained when elements combine

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ANOTHER POEM

To smash the simple atom

All mankind was intent.

Now any day, the atom may

Return the compliment!Odgen Nash

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Three Groups of Elements

Metals – Na, Ca, Fe, Co, Ag Have luster, conduct electricity and heat, are

ductile and malleable Have 1-3 electrons in their outer shells Form ionic bonds

Nonmetals – C, I, Cl, O Do not shine, do not conduct electricity or heat,

are not ductile or malleable Have 5-8 electrons in their outer shells Form covalent bonds

Metalloids – As, Ge Si Usually have 4 electronic in their outer shells, or

on ―line‖ between metals and nonmetals Have some properties of metals and of nonmetals

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Compounds

Compounds are substances composed of two or more elements

Examples: NaCl, water (H2O)

They are combined in definite proportions

They have definite composition

They cannot be separated by physical means

They can be separated by chemical means

4 million compounds have been reported

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Chemical Bonding

Outer shell electrons play an important role in bonding Goal is to maximize stability via perfect outside

shell (like Nobel Gases)

8 electrons in outer shell is extremely stable.

Elements may share or transfer electrons Ionic bonds – transfer of electrons, occurs

between metal (or hydrogen) and nonmetal

Covalent bonds – sharing of electrons, occurs between two nonmetals

Basis of live (all carbon compounds are covalently bonded)

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ODE TO CARBON

(A POEM BY ANOTHER NAME)

What is carbon? You may ask. To tell you is no easy task.

Carbon is in most compounds. Her combinations have no bounds.

Carbon is a lump of coal, dug out of a miner’s hole.

A diamond carbon also is—a stone that is more hers than his.

Carbon as a fossil fuel is even more a precious jewel.

As hydrocarbon, she’s the gas that make our cars go extra fast.

Branching, bonding, even chains, dating isotopes in it’s range.

Multiple uses combined and free. Her value is no mystery!

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Other Chemical Bonds

Metallic bonds Form when overflow electrons leave their atoms and

wander freely throughout metal Can be one element, like Fe, Al, or C Or a mixture of elements

Brass (Cu and Zn) and bronze (Cu and Sn)

van der Waals bonds Cohesive forces

when there is a weak atraction of atom A‘s nucleus (+) with atom B‘s electrons (-)

Examples are candle wax, talcom powder, and hydrogen bonds When hydrogen bonds, it‘s lone electron is shifted

and the exposed positive nucleus is weakly attracted by other electrons

happens in water and makes it a good solvent

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The Three (Four) States of Matter

An ice cream soda contains all three states of matter: solid, liquid, gas

Transition from one state to another requires energy (melting, boiling, solidification, sublimation)

The ―fourth‖ state of matter is plasma Most common state in universe (stars)

Requires extremely high temperatures

Gases take on different character

Electrons are striped off atoms (just a few, as in fluorescent light, or completely, as in stars)

Exhibit properties not common to gases (conduct electricity and can be confined in magnetic fields)

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A VERY LOVELY POEM

Solid is the chair on which I sit.Liquid is the tea on which I sip.

But gases—these are the most difficult of them all.Tiny elements freely float about, plagued by loneliness.

Shy ones drift round in dazed pursuit,longing for the perfect other—not driven to mingle.

Others are bold.Eagerly introducing themselves, pompous and flaunting,

They are considered to be ungenial and abrasiveby the more conservative crew.

Hovering, they soundlessly shiveras a small explosion discharges within a glass beaker

before the chalkboard.Judy Copenbarger

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Physical and Chemical Changes

Physical change – will not alter basic properties of substance

No new substance is formed

Change in shape, size, or state

Why popcorn pops (water in kernel changes state)

Chemical change – new substance is formed with different properties

Requires a chemical reactions

May also result in production of light, heat, gas, color change, or precipitate

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ANOTHER @?!#* POEM

A chemical change is fun to see

I know how to tell if one happens to be!

Exothermic or endothermic—heat absorbed or released

Or the sign of a color change easily policed.

Production of a gas, with bubbles galore

Or the glow of light energy; and there‘s even more!

Sometimes a solid will precipitate out

And that‘s what reactions are all about!

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Chemical and Physical Changes

A new substance coming into existence

A new appearance visible to the human eye

With logic and persistence

The truth behind chemical and

Physical changes we cannot deny.

Grass extending in height

Combining with all underground

Escaping the deadly blight.

A chemical change we have now found

Leaves changing color in fall

Release their hidden hues

Such beauty in them all.

A physical change is what comes to be true

The difference not simply seen

Requires thought and time.

The truth of the complicating two lies between

The obvious and the working mind.

By Sandra Ruiz

http://www.ncrel.org/mands/docs

/6-12.htm

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Types of Chemical Reactions

Composition – two or more substances combine A + B AB Sulfur (car emissions) + oxygen sulfur dioxide, which

causes chronic bronchitis and emphysema

Decomposition – one substance breaks down AB A + B Hydrogen peroxide water + oxygen

Single Replacement – an uncombined element replaces another element in a compound A + BC AC + B Magnesium + hydrochloric acid magnesium chloride +

hydrogen

Double replacement – two compounds exchange ions AB + CD AD + CB Hydrochloric acid + magnesium hydroxide magnesium

chloride + water

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Solutions, Colloids, Suspensions

A solution is a homogeneous mixture

Is not a pure substance

Can be separated by physical means

Has a solute – substance being dissolved; usually the smaller amount

And a solvent – substance doing the dissolving; usually the larger amount

Colloids and suspensions are not true solutions

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Acids, Bases, and Salts

Inorganic compounds can be classified into four broad categories: Acids, bases, salts [and oxides (rust)]

pH is a means of measuring the acid/base strength of solutions (pH expresses the hydrogen ion concentration) pH from 1-6 = acidic, 7 = neutral, 8-14 = basic

―pH balanced‖ means the substances matches the pH of what it is balanced with

Acids, bases, and salts may form electrolytic solutions Conduct electricity because they contain ions

Acids and bases can be distinguished using indicators Indicators – change color in the presence of acids or

bases

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A LITTLE POEM

Little Johnny took a drink

But now he‘ll drink no more

For what he thought was H-2-O

Was H-2-S-O-4!

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A LOVE POEM

Oh my love is like a greenish-yellow gas, Chlorine,That has newly gained an electron;

Oh my love is like a negatively charged ion,That is now named Chloride.

As fair art thou, my attractive gas,So deep in love am I:

That I gave you an electron, my dear,Thus I became positively charged.

Till our attraction gives reaction, my love,To form white solid—table salt;

And I will love thee still, my dear,When our particles are arranged in crystals of sodium chloride.,

And fare thee well, my only love.While the crystal is held together by ionic bond forces,

And I will come again, my love,Tho‘ it were ‗cross an ocean of ten thousand miles.

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AN OLD-FASHIONED LOVE SONG

Just a little atom of chlorine, valence minus one.

Swimming through the sea, diggin' the scene, just havin' fun.

She's not worried about the shape or size of her outer shell.

It's fun to ionize! Just a little atom of chlorine with an unfilled shell.

Somewhere in that sea lurks handsome sodium

With enough electrons on his outside shell plus another one.

"Somewhere in this deep blue sea, there is a negative for my extra energy

Yes, somewhere in this foam, my positive will find a home.”

Then unsuspecting chlorine felt a magnetic pull

She looked down and her outside shell was full!

Sodium cried "What a gas, be my bride,

And I'll change your name from chlorine to chloride!"

Now the sea evaporates to make the clouds for rain and snow,

Leaving her chemical compounds in the absence of H2O

But the crystals that wash upon the shore are happy ones,

So if you never thought before, think of the love that you eat when you salt your meat!

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Matter and Energy

Every substance has a specific amount of energy associated with it

When substances react chemically, they can either lose or gain energy

Chemical reactions are either exothermic (heat-producing) or endothermic (heat-utilizing)

This is because old bonds are broken (requires energy) and new bonds are formed (releases energy)

Law of Conservation of Mass and Energy

The total sum of matter and energy in the universe is always the same (constant)

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THE VERY LAST POEM

When studying matter,

What matters is the subject matter

Which, in this case, is the subject of matter.

When studying energy,

What matters is how much energy

You bring to the subject matter,

Because the energy of the matter

Is your ability to do work!