warm-up 3/21/11
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Warm-up 3/21/11. Review questions: List as many elements as you can think of. Then list as many compounds as you can think of. - PowerPoint PPT PresentationTRANSCRIPT
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 3/25/11 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 ANIMATION
Chemical 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 SO3
2- sulfite PO43- 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 nameWrite the anion name 2nd
Change the ending of thename to –ide.
Flash Card On the front
write:
Polyatomic Ion
On the back write:
Ion consisting of many covalently bonded atoms
WBCZinc Fluoride Zn+2
F-1
WBCPlumbous Bromide Pb+2
Br-1
WBCStannous Sulfide Sn+2
S-2
WBCSilver Phosphide Ag+1
P-3
WBCLead (II) Bromide Pb+2
Br-1