Elements compounds ◦ New properties are created Why do elements form compounds? To become more...
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Transcript of Elements compounds ◦ New properties are created Why do elements form compounds? To become more...
Elements compounds◦ New properties are created
Why do elements form compounds? To become more chemically stable by
getting a complete outer energy level and lowering potential energy.
What are chemical formulas? A formula that tells you number of atoms each element in a compound represented by symbols and subscripts
Subscripts◦small numbers to the lower right of the chemical symbol
◦Represents the number of atoms of that element present in the compound
***the subscript of 1 is never written in a chemical formula; it is understood since the chemical symbol is there****
Looking at the following formulas state the number of atoms for each compound.
NH4OH NH4C Ag2O 2 K2SO4
Ca (NO3)2
3 Na2S 2 Al2(SO4)3
Remember
Ionic compounds
Covalent Compounds
Between metals and nonmetals
Cations and anions
Transferring electrons
Between nonmetals and nonmetals
Sharing electrons
What are characteristics of monatomic ions?
Ions formed from a single atom Cations and anions
What are binary ionic compounds? Compounds composed of two elements
Total number of positive and negative charges must be equal
What are characteristics of polyatomic ions?
Form ternary compounds (3 elements)
Covalent molecules with a charge Behave as if they were one atomic ion
Ammonium – NH41+
(only positive one) Hydroxide – OH1-
Nitrite – NO2 1-
Nitrate – NO3 1-
Sulfite – SO3 2-
Sulfate – SO4 2-
Carbonate – CO3 2-
Bicarbonate – HCO3
-
Phosphate - PO4 3-
Chlorate – ClO3-
Chlorite – ClO2-
Cyanide – CN-
Acetate – C2H3O2-
What are common polyatomic ions?
Remember, oxidation numbers tell how many electrons an atom has gained, lost, or shared to become stable.
Shown as superscripts. Main group elements the oxidation number
is set. The transition elements and those of group 14 vary.
We use oxidation numbers and their least common multiples to write formulas
So, if both subscripts are divisible by the same number, they must be reduced
to have formula in proper form. When writing formulas, the compound
should be neutral (same number of + and - charges)
Type I compounds – ionic compounds made from main group 1, 2, 13 metals and nonmetals of groups 15, 16, 17
Type II compounds – ionic compounds made from transition metal and nonmetal; named by using stock system (using Roman Numerals)
Type III compounds – covalent compounds composed of 2 non-metals; named using prefixes
Terms to Know
TYPE I COMPOUNDS Write cation (metal) name first Then, write the nonmetal name. Drop the ending and add –ide to the end
Ex. Nitride, sulfide, fluoride, oxide, bromide, iodide, chloride, telluride, phosphide
LEQ: How do you name ionic compounds?
If it is a ternary compound (with a polyatomic ion)
First write name of cationThen write name of polyatomic ion
LEQ: How do you name ionic compounds?
TYPE II COMPOUNDS (named using stock system) If it is a transition metal, name the cation first, then put
a Roman Numeral after its name to represent its oxidation number!!! ◦ Look at the subscript of the nonmetal for this
information!!! Then name the anion. Remember to drop the ending and
add –ide or if it is polyatomic name the polyatomic ion.
LEQ: How do you name ionic compounds?
Practice Naming Ionic Compounds MnO2
Ca (NO3)2
BaSO4
Cu3P2
AgCl B2O3
MgCl2 Ba (OH)2
LEQ: How do you name ionic compounds?
Practice Naming Ionic Compounds-Answers MnO2 – Manganese (IV) oxide Ca (NO3)2 – Calcium nitrate BaSO4 – Barium sulfate Cu3P2 – Copper (II) phosphide AgCl – Silver (I) chloride B2O3 – Boron oxide MgCl2 – Magnesium chloride Ba (OH)2 – Barium hydroxide
LEQ: How do you name ionic compounds?
Bell Work 01/22/13
Name the following ionic compounds
Be (OH)2
Mn (NO3)3
FePO4
LEQ: How do you name ionic compounds?
Bell Work 01/22/13
Name the following ionic compounds
Be (OH)2 – Beryllium hydroxide Mn (NO3)3 – Manganese (III) nitrate FePO4 – Iron (III) phosphate
LEQ: How do you name ionic compounds?
1. Write the ions beside each other (first cation then anion)
2. Write the oxidation of each as superscripts w/ charge
3. Drop the +/- signs4. Crisscross superscripts so they
become subscripts5. Reduce when possible
LEQ: How do you write the formula of an ionic compound?
Practice
Write the formula for the following
TYPE I compounds Magnesium chloride
Potassium iodide
LEQ: How do you write the formula of an ionic compound?
Practice-Answers Magnesium chloride- MgCl2 Potassium iodide- KI
LEQ: How do you write the formula of an ionic compound?
Practice on your own
Write the formula for the following
Type I compounds
Boron oxide Beryllium and Nitrogen
LEQ: How do you write the formula of an ionic compound?
Practice-Answers Boron oxide- B2O3
Beryllium and Nitrogen – Be3N2
LEQ: How do you write the formula of an ionic compound?
Write the formula unit for the following type I compounds:
Lithium nitrideSodium fluoride
LEQ: How do you write the formula of an ionic compound?
Bell Work 1/15/13
Write the formula unit for the following:
Lithium nitride – Li3N
Sodium fluoride - NaF
LEQ: How do you write the formula of an ionic compound?
How do you write the formula of an ionic compound with a transition metal? Written as Roman Numerals
Ti (4+, 3+) Cr (2+, 3+, 6+) Mn ( 3+, 4+, 6+) Fe (2+, 3+) Co (2+, 3+) Ni (2+, 3+) Cu (2+, 1+) Ag (1+) Zn (1+, 2+) Pb (2+, 4+) Sn (1+, 2+, 4+)
LEQ: How do you write the formula of an ionic compound?
When it is a transition metal (type II compound).
First, write the symbol of the cation. Use the roman numeral for the oxidation number.
Then, write the symbol for the anion and use periodic table to determine its oxidation number.
Criss-cross oxidation numbers. Reduce if necessary.
LEQ: How do you write the formula of an ionic compound?
PracticeWrite formula for the following
Iron (III) oxide Zinc (II) chloride Silver (I) chloride
LEQ: How do you write the formula of an ionic compound?
Practice Write formula for the following
Iron (III) oxide – Fe2 O3
Zinc (II) chloride – Zn Cl2 Silver (I) chloride – Ag Cl
LEQ: How do you write the formula of an ionic compound?
PracticeWrite formula for the following
Copper (II) phosphide Manganese (IV) oxide Lead (IV) sulfide
LEQ: How do you write the formula of an ionic compound?
Practice Write formula for the following
Copper (II) phosphide – Cu3 P2
Manganese (IV) oxide – Mn O2
Lead (IV) sulfide – Pb S2
LEQ: How do you write the formula of an ionic compound?
How do you write the formula of an ionic compound with a polyatomic ion?
Treat the polyatomic ion as one Use parenthesis around polyatomic ion Crisscross oxidation numbers to determine
formula Only reduce subscripts that are
outside of the parenthesis
LEQ: How do you write the formula of an ionic compound?
Ca 2+
Mg 2+
Ba 2+
Ba 2+
LEQ: How do you write the formula of an ionic compound?
Cation Anion
NO 3 –
PO 4 3-
OH –
SO 4 2-
Bell Work 1/23/13Practice writing formulas with polyatomic ionsSodium carbonateCalcium carbonateAluminum carbonateSodium phosphateCalcium phosphateAluminum phosphate
LEQ: How do you write the formula of an ionic compound?
Practice writing formulas with polyatomic ionsSodium carbonate – Na2CO3
Calcium carbonate – CaCO3
Aluminum carbonate – Al2(CO3)3
Sodium phosphate – Na3 PO4
Calcium phosphate – Ca3 (PO3)2
Aluminum phosphate – AlPO3
LEQ: How do you write the formula of an ionic compound?
Between nonmetals and nonmetals Type III Compounds that does not contain
cations and anions You do NOT crisscross to determine formula Look at the name, it tells you the formula!!!! You MUST KNOW AND USE prefixes (it
tells the number of atoms of the element in the compound)
DO NOT REDUCE FORMULAS!!!
LEQ: How do you write the formula for a covalent compound?
Prefixes
1. Mono-2. Di-3. Tri-4. Tetra-5. Penta-
6. Hexa-7. Hepta-8. Octa-9. Nona-10. Deca-
LEQ: How do you write the formula for a covalent compound?
RULE!!!! Do NOT use “mono” on the first element!
Practice writing covalent compound formulas
Dinitrogen trioxideCarbon tetrahydridePhosphorous pentoxideDisulfur trifluoride
LEQ: How do you write the formula for a covalent compound?
Practice writing covalent compound formulas - Answers
Dinitrogen trioxide – N2O3
Carbon tetrahydride – CH4
Phosphorous pentoxide – PO5
Disulfur trifluoride – S2F3
LEQ: How do you write the formula for a covalent compound?
First, use the nonmetal furthest to the left on the periodic table. If they are in the same group, write the element with the larger period number first. Write Prefix and name of element. DO NOT USE MONO!!!
Then, write the second nonmetal with prefix, root, ending in –ide.
Look at subscript to determine the prefix needed
LEQ: How do you name covalent compounds?
Bell work 01/30/13
Name the following covalent compound! PCl3 NH3
LEQ: How do you name covalent compounds?
Practice naming covalent compounds PCl3 – Phosphorous trichloride NH3 – nitrogen trihydride
LEQ: How do you name covalent compounds?
Practice naming covalent compounds on worksheet
LEQ: How do you name covalent compounds?
Compounds with or without water hydrates (compounds with water) Name ionic compound as usual; but, water
is covalent compound so must use prefixes Ex. CaSO4 · 2 H2O
◦ Calcium sulfate dihydrate Anhydrous (without water)
Binary Acid H + element Hydro ic acid H + F Hydrofluoric acid
LEQ: How do you name acids?
H + Polyatomic acid (“oxo” acids) DO NOT START WITH HYDRO- ate ic “I ate something ic-ky” Nitrate nitric acid HNO3
ite ous “I took a b-ite of something delicious” Nitrite nitrous acid HNO2
LEQ: How do you name acids?
Naming Bases Name the metal CATION first; it keeps its
name as listed in the Periodic Table. The polyatomic ion "hydroxide" (-OH) also
keeps its name. Examples: LiOH is "lithium hydroxide" Ca(OH)2 is "calcium hydroxide" NH4OH is "ammonium hydroxide"
LEQ: How do you name bases?