Bonding, Compounds, Reactions. Periodic Table Review.
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Transcript of Bonding, Compounds, Reactions. Periodic Table Review.
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 Table
Noble Gas
Non-metals
Metalloids
Metals
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
Chemical
formula
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 Monoxide
The 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 As
Why 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
H2O
Magnesium 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 wizard
Your definition Important Points
Real example Analogy/memory hookAlloy
Not 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 hook
Synthesis
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 hook
Single 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 hook
Double 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 hook
Decomposition
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 hook
Combustion
Reaction
A reaction where two of the products are water and carbon dioxide
Combustion = fire
Picture 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 hook
Endothermic
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 hook
Exothermic
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 act
Ag + 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