Bonding, Compounds, Reactions

Periodic Table Review

What does the periodic table tell me?

• Element symbol• Atomic number: number of protons (and

usually electrons, neutrons)• Atomic mass: the average of all the isotopes’

mass• What type of element it is (metal, nonmetal,

etc)• What elements can bond together (valence #)• In what ratio elements bond (oxidation #)

Reading the Periodic Table: Elements

S16

32.06

Element symbol

Atomic mass

Atomic number

Types of Elements• Metals: usually shiny, conductors,

malleable, ductile, solids at room temperature. On left side of periodic table

• Non-metals: gas or brittle solid at room temperature, insulators. On right side of periodic table.

• Metalloids: have properties of both metals and non-metals. Between metals and non-metals.

Three types of Elements

Things to remember with symbols

• They are either one or two letters.• Only the first letter is capitalized!• Some symbols are based on the Latin name• Some of the newest symbols use three

letters until they are renamed (the atomic number in Latin)

Periodic TableNoble Gas

Non-metalsMetalloid

sMetals

Transition Metals

Halogen

Types of Elements• Noble Gas: Chemically stable. Has outer valence

level full. “Happy” AKA: Inert elements. Don’t bond with others.

• Halogens: Are non-metals. Bond VERY easily. Have 7 electrons in outer shell.

• Non-metals: Do not easily conduct electricity or heat.• Metalloids: Have traits of both metals and non-metals.• Metals: Good conductor of heat and electricity, shiny,

ductile (pulled into a wire), and malleable (pounded into flat sheets)

• Transition metals: Metals that can have two different valence numbers. Is shown in the formula. Example: Fe (II)

Periodic TableAlkali metals Alkaline Earth

metals

Transition metals

Chemical Bonds

• The forces that hold atoms or ions together

Word wizard: Ionic Bond

Ionic Bond

Your definition Important Points

Examples Non-Examples

Bond that is formed by the “stealing” of electrons.

One atom is now + and one is now -. This makes them attract to each other. Most are solid at room temp.

Sodium Chloride: NaCl

Sugar: C6H12O6

Water: H2O

Diatomic molecules: Cl2, H2, N2 (gasses)

Word wizard: Covalent Bond

Covalent Bond

Your definition Important Points

Examples Non-Examples

Sodium Chloride: NaCl

Sugar: C6H12O6

Water: H2O

Diatomic molecules: Cl2, H2, N2 (gasses)

Bond that is formed by the “sharing” of electrons.

A stronger bond than ionic. Atoms can share more than one electron. Most are liquid or gas at room temp.

Word wizard: Anion

anion

Your definition Important Points

Examples Non-ExamplesChlorine

Oxygen

Nitrogen

Non-metals

An ion that has a negative charge; has extra electrons.

Anions have more electrons than protons. This makes them negative overall.

Sodium

Potassium

Magnesium

Metals

Word wizard: Cation

Cation

Your definition Important Points

Examples Non-Examples

An ion that is positively charged; has less electrons

Cations lose electrons. They have more protons than electrons and are positively charged.

SodiumPotassiumMagnesiumMetals

ChlorineOxygenNitrogenNon-metals

Word wizard: Chemical Formula

Chemicalformula

Your definition Important Points

Examples Non-Examples

A shorthand way of writing compounds using their symbols.

Large and small letters.

Shows what elements are in a compound and how many of each.

H2O

C6H12O6

NaCl

Water

Sugar

Salt

Word wizard: Chemically Stable

Chemically Stable

Your defintion Important Points

Examples Non-Examples

Elements that have the outer electron shell full.

Also called “Noble Gases” or “Inert Elements”

Will not typically bond with other elements.

Likes to be ALONE!

Helium Krypton

Neon Xenon

Argon Radon

Gold Carbon

Sodium Nickel

Potassium Oxygen

Valence Numbers

1 2 3 54 86 7Valence

Diatomic Molecules• Covalent bond

between identical atoms.

• Usually a gas• Examples:

– H2 (hydrogen gas)– O2(oxygen gas)– N2(nitrogen gas)

• Nitrogen has 5 electrons in the outer shell.

• It wants 8.• Two nitrogen atoms

share three electrons.

• BONDED!

Making Compounds

Let’s bond, shall we?

Valence Numbers• Valence electrons: how many electrons are

in the outer shell.• Chemically stable: elements having their

outer shell full. The noble gases are chemically stable without bonding.

• To fill the outer shell, elements can share or steal electrons (bond).

• To be “Happy” atoms typically want 8 electrons in the outer shell (ionic or covalent bonds)

Ionic bonding• Stealing electrons• This makes one

negatively charged (it has an extra electron that it stole). The other is now positively charged (had an electron taken). Opposites attract!

• Ionic bonds are weaker than covalent.

• Compounds that are solids at room temperature are usually from ionic bonds.

Covalent Bonding

• From sharing electrons

• Covalent bonds are stronger than ionic

• Compounds that are liquids or gas at room temperature are typically covalent bonds.

• Diatomic: Some elements will covalently bond with themselves!

Common Household Compounds

Salt:

Water:

Carbon Dioxide:

Carbon Monoxide:

Stomach Acid:

Ammonia:

Bleach:

Sand:

Baking Soda:

Propane:Vinegar:

NaCl

H2O

CO2

CO

HCl

NH4

NaClO

SiO2

NaHC03

C3H8HCH3O2

Ionic Compound Naming

• Metal first then nonmetal• Nonmetal gets –ide ending

Dihydrogen MonoxideThe dangers, uses and potential threats posed by this chemical, Dihydrogen Monoxide, are widespread, and some feel, terrifying. Here is just a small taste of what Dihydrogen Monoxide (DHMO) is: · Some call Dihydrogen Monoxide the "Invisible Killer" · In it’s gaseous form, DHMO can cause severe burns · Dihydrogen Monoxide is found in all cancerous tumors· Athletes use DIHYDROGEN MONOXIDE, or DHMO, to enhance

performance · Dihydrogen Monoxide has been found to cause failure in automotive

breaks · Dihydrogen Monoxide is a major component of acid rain · Thousands die each year after inhaling dihydrogen monoxide · Dihydrogen Monoxide can be deadly

Visit DHMO.org to find out more

What’s in a name?

• Mono = one• Di = two• Tri = three• Tetra = four• Penta = five

• Examples:– Carbon Monoxide CO– Carbon Dioxide CO2

– Dihydrogen Monoxide ??H2O

Covalent Compound Naming

• If only one atom in first element the name does not get a prefix

• The element farther to the right on the periodic table is named second and ends in -ide

Dot Diagrams• What you need to know to make a dot

diagram:• Chemical symbol• valence number

• How to draw the dot diagram of an element:1. Write the symbol

2. Find the valence number3. Fill in dots

– two together (the S ones)– one in other sides until you run out of room.

P

More Dot Diagrams

Li F

Mg

SeKr

Ge

I’m still seeing dots!

Sr AsWhy is this one right?

HeBecause Helium only has two electrons in the first place!

Oxidation numbers

-1-2-3+/-4+3+2

+1

Making Compounds• Criss-Cross Method:

– List the Metal first, non-metal second.– Write the oxidation number above the symbol.– Criss-cross the numbers. (a 1 does not need to

be written, drop the + or -)– Final answer lists only the subscripts (numbers

below the line)– If they are the same number, they cancel out

Example: Combine Hydrogen and Chlorine

Cl+1 -1

= HClH

Now try these...

H O+1 -2

Hydrogen and Oxygen

H2OMagnesium and Nitrogen

Mg N+2 -3 Mg3N2

Writing Equations• Remember the

“criss cross” method.– Use the oxidation

number– Don’t write in 1’s

or the charges– Oxidation

numbers of transition elements are given in a roman numeral.

– Put in “lowest terms”

H O+1 -2

H2O

Example: Combine H and O

Example: Combine Fe (III) and O

Fe

O -2+3

Fe2O3

Writing Equations: something new• Monoatomic Ions:

– “normal”– one element– can get from the periodic table or roman numerals– what you’ve been working with– Example: H20

• Polyatomic Ions:– compounds that always work together.– Always has more than one element– Get the information off a chart– Criss cross method still works.– Keep these elements together!

Example: Combine Potassium and Permanganate

K MnO4

+1 -1

KMnO4

More Practice: Polyatomic Ions

Combine: Iron (II) and Nitrate

Fe NO3+2 -1

Fe(NO3)2

Combine: Calcium and Carbonate

Ca CO3+2 -2

CaCO3

Word wizardYour definition Important Points

Real example Analogy/memory hookAlloyNot ALL metals are mixtures. (All = alloy)Alloys are like allies (mixed but not the same)

Two or more metals melted down and mixed together.

Sterling silver, 14 karat gold, bronze, brass

The mixture can have new properties. (lower melt point, stronger, etc.

Word wizardYour definition Basic equation

Real example Analogy/memory hookSynthesis Reaction

Reaction where substances are combined to make a new substance.

Like two people going out and becoming a “couple”.Dating is a “sin”

2Mg + O2 2MgO

A + B AB

Word wizardYour definition Basic equation

Real example Analogy/memory hookSingle replacement

Reaction

One ingredient “kicks out” the other. Leaders always stay leaders!

Getting “dumped” for someone else.One ends up single

A + BC AC + B

D + BC BD + C

Li + FeBr2 LiBr + Fe

Word wizardYour definition Basic equation

Real example Analogy/memory hookDouble replacement

Reaction

Elements will change partners in this type of reaction. Leaders are always leaders!

Switching dates at the prom.Nobody gets left alone!

AB + CD AD + CB

AgNO3 + NaCl AgCl + NaNO3

Word wizardYour definition Basic equation

Real example Analogy/memory hookDecomposition

Reaction

A substance is broken down into its “parts” in this reaction

A couple breaking up.Things “break down” when they decompose.

AB A + B

2H2O H2 + O2 elec

Word wizardYour definition Basic equation

Real example Analogy/memory hookCombustion

Reaction

A reaction where two of the products are water and carbon dioxide

Combustion = firePicture a fire with smoke (CO2) and water(H20) to put it out.

A + B CO2 + H20

HCl + Na2CO3 CO2 + NaCl + H2O

Word wizardYour definition Important Points

Real example Analogy/memory hookEndothermic

Reaction

Chemical reaction where heat is ABSORBED.

Heat being absorbed makes it feel COLD.

Break and shake ice pack. (Heat is absorbed by ice pack, but it feels cold)

Endo has a “d” in it. Cold has a “d” in it.Endothermic reactions FEEL cold.

Word wizardYour definition Important Points

Real example Analogy/memory hookExothermic

Reaction

Chemical reaction where heat is released.

This reaction will feel warm/hot.

“Hand warmers” BenGay, Thermocare hot wraps

“Exo” = “exit”Heats EXITS an exothermic reaction. (it feels warm)

You can’t play “God”

• Law of Conservation of Mass says that we can’t create or destroy mass!

• Example: the weight of a piece of paper will be the same as the weight of the ash, smoke, etc after you burn it!!

• In chemical reactions, you need to have the same amount of atoms before and after the reaction!

It’s a balancing actAg + H2S Ag2S + H2

Ag

H

S

Ag

H

S

1

2

1

2

2

1

Not Balanced! Conservation of mass says we can’t create or

destroy anything!!

It’s a balancing act

Ag + H2S Ag2S + H2

Ag

H

S

Ag

H

S

1

2

1

2

2

1

2

2