chapter 5: the structure of matter

Chapter 5: The Structure of Matter

Section 1: Ions & Ionic Bonds

Atoms of different elements can join to produce new substances, called compounds.

– Definition: compound – a substance composed of atoms from 2 or more different elements.

When atoms join together, the process is called atomic bonding.

– Definition: atomic bonding – the process by which multiple atoms link together.

Most of the time, atoms don’t just spontaneously bond together. Something needs to happen in order to “set the mood”.

You should know by now that opposite charges attract, right?

• Atoms begin with the same number of p+ and e-, which makes them neutral. (I.E. NO charge)– Atoms can develop a charge if electrons are lost

or gained.

• Definition: ionization – the process that causes a neutral atom to become charged.

Remember “valence electrons”? Remember that they control how an element acts?

Atoms can gain or lose VALENCE electrons. But WHY?The Octet Rule is why…

• The Octet Rules says:–Most atoms will gain or lose electrons in

order to have 8 in the outer energy level.

• By following the octet rule, atoms become stable, but they also become charged.

Na Na1+Sodium…

ionization Sodium ION

• Metal elements tend to LOSE ALL of their valence e-.• Nonmetals tend to GAIN more valence e-.

METALS

NONMETALS

• Definition: cation (cat – ion) – a positive ion.• Definition: anion (an – ion ) – a negative ion.

So, how is the charge of an ion determined?

The more electrons lost or gained, the bigger the charge!

Na1+

Mg2+ Al3+ N3-

O2-Cl1-

What determines if an ion is + or - ?• Electrons are negative particles…

– If an atom loses some, then it is left with a positive charge.

Sodium now has 1 more proton than electrons. It gets a charge of 1+.

Na11 p+

11 e-

Na1+11 p+

10 e-Ionized!

– Atoms that steal more electrons get a negative charge.

Fluorine now has one more electron than protons.It gets a charge of 1-.

F9 p+

9 e-

F 1-9 p+

10 e-

Ionized!

Once the ATOMS have been charged into IONS, they are able to bond together.

Na 1+ Cl 1-Opposites Attract!

NaCl

SODIUM CHLORINE

SODIUMCHLORIDE

SODIUM CHLORINE

Opposites Attract!

SODIUMCHLORIDE

•Definition: ionic bond – an atom bond formed between metals (cations) and nonmetals (anions).•Ionic Compounds are called “salts”.

•Ionic compounds are crystalline solids.•They have high melting temperatures.•They are hard and brittle.

•Ionic compounds are electrolytes.•Definition: electrolyte – a substance that conducts electricity when dissolved.

–When dissolved in water, the ions come apart.–This allows electricity to flow through them.

++

+

+

+-

--

-

-

-

•Lets look at how Magnesium and Fluorine bond...

Ionic Compound Formulas

MG2+

Magnesium Ion

F1-

Fluorine Ion

To make a compound with them, you have to make sure the charges cancel.

MG2+

F1-

F1- It takes 1 Magnesium (Mg1)It takes 2 Fluorine (F2) MgF2

Neutral!

Neutral!

Neutral!

+

+

+

+

+

+

+

+

+

+

+

+

--

- -

---

-

--

ElectronTHEFT!

-

- -

-

-

-

--

- Negative!

F1-

+

++

++

+

+

++

+

+

Positive!

Na1+

++

+

++

++

+

+

+

+

++++

++ +

+

+

++

+

+

Chapter 5: The Structure of MatterSection 2: Molecules & Covalent Bonds

Sugar is a covalent compound.

• Definition: covalent bond – an atomic bond formed between two nonmetal elements. H2O and NH4 are two examples of compounds with

covalent bonds.O2, O3, H2, F2…these are also covalent bonds.

• Definition: molecule – a substance composed of two or more atoms.– Molecules have covalent bonds!

• Most covalent compounds will easily melt.• They are not electrolytes.

Sugar melts easily to become caramel!

• Definition: diatomic molecule – a molecule made up of only 2 atoms.

• Some nonmetal elements can form covalent bonds with themselves.

– For example:– Oxygen can bond with other oxygen atoms by forming

covalent bonds.

Each line represents 2 SHARED electrons.

This is the dot diagram for the

O2 Molecule.O O

• The simplest molecule is H2.– There are 7 elements that make diatomic

molecules with themselves naturally.• The 7 Diatomic Elements are:

– Hydrogen – H2

– Nitrogen – N2

– Oxygen – O2

– Fluorine – F2

– Chlorine – Cl2

– Bromine – Br2

– Iodine – I2

H HH2

Look at that!They make a “7” on the periodic table! (Don’t forget Hydrogen!)

Living things are mainly composed of covalent compounds.

• Definition: organic compound – a molecule that contains carbon and usually hydrogen.

– All living things contain organic compounds.

C6H8O7

What is one organic compound that you think

is found in oranges?

• Hydrocarbons are an extremely important organic compound.– Definition: hydrocarbon – an organic compound

made only of H and C.

– Hydrocarbons account for most of our fuel…• OIL• GASOLINE• PROPANE• BUTANE• COAL• These are all HYDROCARBONS!

• Definition: alcohol – an organic compound composed of O, H, and C.– There are many different types of alcohol…– Alcohols are very flammable, and evaporate quickly.

Alcohols have been produced

by humans since around 900 AD.

Chapter 5: The Structure of MatterSection 3: Important Compounds & Molecules

There are millions (billions?) of compounds and molecules that exist throughout the universe.

Some of these compounds & molecules are vitally important.

• We’ll take a look at a few of the most important compounds and molecules.

• The Water Molecule: H2O– Water is vital for ALL forms of life.– It is extremely good at dissolving other substances, and

is known as the universal solvent (dissolver).

– About 70% of our planet is covered in water.– Less than 1% of all the water on Earth is fresh (drinkable)

water!

– Interesting fact: humans have adapted to prefer cold water to drink because it is less likely to contain bacteria.

• Sodium Chloride: NaCl– Also known as “table salt”.

– NaCl is responsible for the saltiness of the oceans.

– Sodium Chloride has had invaluable uses for thousands of years:• NaCl is used to preserve foods.• It is used for cooking and cleaning wounds.• It is used to clean teeth & as a mouthwash.

– NaCl is used to produce chlorine gas.

• Polyethlyene (plastic): C2H4

– What would the world be like without PLASTIC?– Think of how many things we use plastic for…

– The first manmade plastic was invented in 1855. • Since then, plastic has evolved into many different forms.

– Polyethylene is the most widely used type of plastic.• It’s main use is for shopping bags.

• Ammonia: NH3

– Ammonia is one of the most widely produced compounds.

– About 80% of the ammonia produced is used to fertilize crops.

– Without ammonia production, our food supply would not be NEARLY as abundant!

– Ammonia is excreted by the kidneys of animals and passed through urine.

– It is often used a cleaner…especially for glass because of its “streak-free” shine.

• Sulfuric Acid: H2SO4

– Sulfuric Acid is primarily used to clean and prepare metals for industrial use.

– The strength of a country’s economy is tied to it’s production of sulfuric acid. Why?

– Most of the metal used in automobiles and appliances has been “cleaned” with sulfuric acid.

– Sulfuric acid is the “acid” in car batteries.

• Potassium Nitrate (gunpowder): KNO3 – Potassium Nitrate is also known as saltpeter.

– The use of potassium nitrate ranges from weapons, to explosives, to fireworks.

– The use of gunpowder as a weapon drastically changed the history of our planet.

– Potassium nitrate has been used since the BC ages…especially in China.

– Interesting Fact: Potassium Nitrate was one produced using bat guano (poo)!

• Silicon Dioxide: SiO2

– Also known as Silica, it is the most abundant mineral on Earth.

– Silica is commonly found in sand.

– The main use of Silica is for glass production, where it is melted and then reshaped.

– Elements and compounds can be added to the melted silica in order to produce colors.

– Natural glass can be created when lightning strikes sand!

• Carbon Dioxide: CO2

– CO2 is needed for photosynthesis. It is a gas that all plant life requires.

– CO2 also helps keep the planet warm by “trapping” thermal energy from the sun.

• Oxygen: O2

– O2 is a product of photosynthesis. O2 is required for respiration in animals.

– Oxygen was added to our atmosphere by plankton and algae over millions of years.