Warm-up 3/21/11Review questions: List as many elements
as you can think of. Then list as many compounds as you can think of.
Teach the teacher questions: If you could start a band what kind of band would you start, what would you call it, and what part would have in it (play guitar, sing, ect.).
Learning Targets: By the end of the class you should know: what happens when elements combine
the two different kinds of bondshow to balance cations and anions for a
chemical bond
Chemical BondsBonding isn’t just for people.
Why do atoms form compounds? TO BECOME STABLE!!What does stable mean to an atom?
Full set of valence electrons Atoms want to have the electron
configuration of a noble gas Atoms will gain, lose or share
electrons in order to obtain a full set of valence electrons
Chemical bonding
Combining ElementsThe chemical & physical properties of
the elements are different than the properties of the compound they make up
Na + Cl2 → NaCl
Reaction of Sodium with Chlorine & Hydrogen with Oxygen
→
Types of BondsIonic Bonds
Contain a metal & a nonmetal (at least 1 of each)
Electrons are gained or lostEx. Salt, NaCl
Covalent BondsContain 2 or more nonmetals or hydrogenElectrons are sharedEx. Water, H2O
Ionic BondingIn an ionic bond, one atoms gives
electrons to another atom.When atoms combine this way, it is
called a formula unit.Ex. NaCl is a formula unit
The charge of a formula unit is always 0.
The positive and negative charges must always balance each other.
FormulasChemical Formula—tells what elements
a compound contains and the exact number of the atoms of each element.Ex. NaCl has 1 atom of sodium & 1 atom of
chlorineEx. H2O has 2 atoms of hydrogen and 1 atom
of oxygen.A subscript (small # written below) is
written after a symbol to tell how many atoms of that element are in the compound.
Rules for FormulasWrite the cation (metal) first. Write the anion (nonmetal) second.
The net ionic charge is zero.Use subscripts to indicate multiple ions.
Write the formula unit in the lowest whole number ratio.
A trick for formula unitsWrite both ions with their charges as superscripts. Cu3+ & O2-
Crisscross the charges to make the subscripts in the formulaDo not put + or – in the formula
Cu3+ & O2-
Cu2O3
Silver Chloride
AgCl
Ag+1 Cl-1
Zinc Phosphide
Zn3P2
Zn+2 P-3
Aluminum Oxide
Al2O3
Al+3 O-2
Warm-Up 3/24/11Review: Give an example of a
formula unit.
Teach the Teacher: What is the best holiday? Are you going to the pow wow?
Flash cardOn the front
write:
subscript
On the back write:
H2O (submarine)
Flash card On the front:
Ionic Bonding
On the back:
When an element gains or loses an electron
Flash Card On the front:
Covalent bonding
On the back:
When atoms share electrons
Warm-Up 3/28/11 Review questions: What is an ionic bond?
(use your flash cards)
Teach the teacher questions: Would you rather be stuck in an elevator with wet dogs or wet cats?
Learning Targets: By the end of the class
you should know: polyatomic ions
Practice with Chemical Formulas Common Name Chemical Formula Types & Number
of Elements involved Sand SiO2
Milk of Magnesia Mg(OH)2
Sucrose C12H22O11
Vinegar HC2H3O2
Ethanol C2H5OH
→
Types of Bonds IONIC BONDS
between metals & nonmetals
Electrons form a give take relationshipmetals give e- (cation)
nonmetal take e- (anion)
Held together by attraction of opposite charges
IONIC ANIMATIONChemical Bonds
Table Polyatomic IonsPolyatomic Ions
The prefix poly- means many in Greek. ion consisting of a molecule with many
covalently bonded atoms act as a single unitpolyatomic ion is also referred as a radical Usually end in –ate & –ite -ide usually indicates binary compounds
+1 CHARGE -1 CHARGE -2 CHARGE -3 CHARGE
ion name ion name ion name ion name
NH4+ ammonium NO2
- nitrite CO32- carbonate PO3
3- phosphite
H3O+ hydronium NO3
- nitrate SO32- sulfite PO4
3- phosphate
Hg22+ mercury(I) OH- hydroxide SO4
2- sulfate
CH3COO-
C2H3O2- acetate S2O3
2- thiosulfate
CN- cyanide CrO42- chromate
CNS- thiocyanate Cr2O72- dichromate
MnO4- permanganate
ClO3- chlorate
ClO4- perchlorate
IO2- iodite
IO3- iodate
Oxidation number—the charge of an ion
1+
2+ 3+ 3- 2- 1-
Multiple Oxidation Numbers
Some metals (other metals & transition metals) can have more than 1 oxidation number.
If an element can have more than 1 oxidation number, the charge of the ion is written as a roman numeral in parentheses.Ex. Copper (I) ion is Cu1+
Copper (II) ion is Cu2+
Mistakes to AvoidRoman numerals are
not written in the formula
Charges are not written in the formula
Don’t drop polyatomic subscripts
Hydroxide, OH, needs parentheses to indicate multiples.
Cu(II)O CuO
K+1Br-1 KBr
CaNO2 Ca(NO3)2
CaOH2 Ca(OH)2
Rules for Naming Ionic Compounds Group A Elements
Write the cation name 1st Cation name is the same as
the element name
Write the anion name 2nd Change the ending of the
name to –ide.
Flash Card On the front
write:
Polyatomic Ion
On the back write:
Ion consisting of many covalently bonded atoms
WBC
Zinc Fluoride Zn+2
F-1
WBC
Plumbous Bromide Pb+2
Br-1
WBC
Stannous Sulfide Sn+2
S-2
WBC
Silver Phosphide Ag+1
P-3
WBC
Lead (II) Bromide Pb+2
Br-1
Warm-Up 3/29/11Review questions: What is the
subscript in H2O? What are some mistakes to avoid (look at notes)!
Teach the teacher questions: What is one of the better board games?
Learning Targets: Balancing equations and the naming of compounds.
Flash Card On the front
write:
Polyatomic Ion
On the back write:
Ion consisting of many covalently bonded atoms (like conjoined twins)
Warm-Up 3/31/11Review: Why are conjoined twins
like polyatomic ions?
Teach the Teacher: What is the best April’s fools prank you have heard of.
Ionic and covalent bonding balancing formula units
Flash Card On the front
write:
Molecule
On the back write:
A group of atoms that are bonded together, neutral charge
Covalent BondsCovalent bonds share electronsComposed of 2 or more nonmetals (and
H)Covalent compounds are called moleculesMolecules can be polar or nonpolarPolar molecule—slightly positive and
negative at parts—but overall neutrale- are unevenly shared
Nonpolar molecule—electrons are shared equally—completely neutral
Comparing ionic and covelent compounds
Covelent compounds Ionic compounds
Smallest particles molecules cations and anions
Origin of bonding electron sharing electron transfer
Forces between particlesstrong bonds between
atomsweak attractions between
molecules
Strong attractions between anions and cations. strong
repulsions between ions of like charge
Elements present close on the periodic table widely separated on the periodic table
Metallic elements present rarely usually
electrical conductivity poor good, when melted or dissolved
state at room temperature solid, liquid, or gas solid
melting and boiling points lower higher
other names molecular compounds salts
• Polar or Nonpolar
– Polar Bonds • an unequal sharing of the e-• Due to a difference of electro-
negativity of the atoms – F is the most electronegative element
on PT
– Non-polar Bonds • an equal sharing of e- • nonpolar bond animation
– Multiple Bonds – More than one pair of electrons can be shared between atoms• Double Bonds = 2 shared pairs of e-• Triple Bonds= 3 shared pairs of e-
Chemical Bonds
Naming Covalent Compounds
Use prefixes to tell how many of each element you have.This is done because you can have
different covalent compounds containing the same elements.
Change the ending of the 2nd element to -ideEx. N2O is dinitrogen monoxide.
You can leave off the prefix mono- on the first element.Ex. NO2 is nitrogen dioxide
Not mononitrogen dioxide
Mono—1Di—2Tri—3Tetra—4Penta—5Hexa—6Hepta—7Octa—8Nona—9Deca—10
Formulas for Covalent Compounds
Use the prefixes as the subscript in the formula.
Ex. Phosphorus TrichloridePCl3
Dinitrogen TetrafluorideN2F4
Covalent or Ionic
Bond between a metal and a nonmetal
Covalent or Ionic Bond between two nonmetals
Covalent or Ionic Can be polar or nonpolar
Covalent or Ionic
H20
Covalent or Ionic
NH3
Covalent or Ionic
NaCl
Covalent or Ionic Roman Numerals are used to
indicate the oxidation state of the metal cation
Covalent or Ionic Carbon tetrachloride
Covalent or Ionic Electrons are gained or lost,
or transferred from one atom to another
Covalent or Ionic
sulfur(VI) oxide
Covalent or Ionic
carbon tetrachloride
Notes to Notecard 1. Why do atoms form compounds?
2. After two elements combined in a chemical reaction, is the new substance the same as the elements that made it? (Yes or No)
3. Which type of bond contains only a metal?
4. A trick for writing formulas is to crisscoss charges, but what do you not put in the formula?
5. What are the little written ionic charges called? (opposite of superscript.)