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


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.


Practice Naming Ionic Compounds MnO2

Ca (NO3)2

BaSO4

Cu3P2

AgCl B2O3

MgCl2 Ba (OH)2


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


Bell Work 01/22/13

Name the following ionic compounds

Be (OH)2

Mn (NO3)3

FePO4


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


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


Practice-Answers Magnesium chloride- MgCl2 Potassium iodide- KI


Practice on your own

Write the formula for the following

Type I compounds

Boron oxide Beryllium and Nitrogen


Practice-Answers Boron oxide- B2O3

Beryllium and Nitrogen – Be3N2


Write the formula unit for the following type I compounds:

Lithium nitrideSodium fluoride


Bell Work 1/15/13

Write the formula unit for the following:

Lithium nitride – Li3N

Sodium fluoride - NaF


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+)


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.


PracticeWrite formula for the following

Iron (III) oxide Zinc (II) chloride Silver (I) chloride


Practice Write formula for the following

Iron (III) oxide – Fe2 O3

Zinc (II) chloride – Zn Cl2 Silver (I) chloride – Ag Cl


PracticeWrite formula for the following

Copper (II) phosphide Manganese (IV) oxide Lead (IV) sulfide


Practice Write formula for the following

Copper (II) phosphide – Cu3 P2

Manganese (IV) oxide – Mn O2

Lead (IV) sulfide – Pb S2


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


Ca 2+

Mg 2+

Ba 2+

Ba 2+


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


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


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-


RULE!!!! Do NOT use “mono” on the first element!

Practice writing covalent compound formulas

Dinitrogen trioxideCarbon tetrahydridePhosphorous pentoxideDisulfur trifluoride


Practice writing covalent compound formulas - Answers

Dinitrogen trioxide – N2O3

Carbon tetrahydride – CH4

Phosphorous pentoxide – PO5

Disulfur trifluoride – S2F3


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


Practice naming covalent compounds PCl3 – Phosphorous trichloride NH3 – nitrogen trihydride


Practice naming covalent compounds on worksheet


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?

Elements compounds ◦ New properties are created Why do elements form compounds? To become more...

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