chemi/ih:chapter8 covalent bonding (click for video)

LecturePLUS Timberlake 1

ChemI/IH:Chapter8 Covalent Bonding (click for video)

Def: bonds in which electrons are SHARED btwn 2 or more nonmetals

Nonmetals have high EN (electronegativity) values so electrons must be shared

Compounds w/covalent bonds are called molecular compounds.

We will learn about 4 types of molecular cpds.

http://chemwest.wetpaint.com/video/11256664/Ionic+vs+Covalent+Bonding+with+cool+demos

http://chemwest.wetpaint.com/video/11256664/Ionic+vs+Covalent+Bonding+with+cool+demos

1. Acids

• Acids are covalent compounds that act like ionic compounds.

• They have H+ as the “cation”.


Acids

• There are 3 types of acids.

• They are named based on the type of ANION they contain:

1.Anion = element

2.Anion = polyatomic ion that ends in “ate”

3.Anion = polyatomic ion that ends in “ite”


Acids

1. If anion is an element, name of acid is “hydro____ic acid” where blank is filled with root of element name

• Ex: HCl


Hydrochloric acid

Acids

2. If anion is a polyatomic ion that ends in

“-ate”, name of acid is “____ic acid” where blank is filled with root of polyatomic ion name

• Ex: HClO3


chloric acidClO3 = “chlorate”

Acids

3. If anion is a polyatomic ion that ends in

“-ite”, name of acid is “____ous acid” where blank is filled with root of element name

• Ex: HClO2


chlorous acidClO2 = “chlorite”

Acids, Summary(copy on P. Table)


Type of Anion

Naming rule Example

Element Hydro___ic acid HCl: hydrochloric acid

Polyatomic “-ate”

____ic acid HClO4: perchloric acid

Polyatomic “-ite”

____ous acid HClO: hypochlorous acid


Covalent Bonding

• By sharing e-s, atoms obtain NGC, which makes them more stable than they were by themselves.

H + H H : H = HH = H2

hydrogen molecule

Covalent Bonding

• single bond shares 1 pair electrons- ex:H2

• double bond shares 2 pairs electron-ex:O2

• triple bond shares 3 pairs electrons-ex: N2



Learning Check(DON’T COPY)

Indicate whether a bond between the following would be

(I) Ionic OR (C) covalent

____ A. sodium & oxygen

____ B. nitrogen & oxygen

____ C. phosphorus & chlorine

____ D. calcium & sulfur

____E. chlorine & bromine


Solution(DON’T COPY)

Indicate whether a bond between the following would be

(I) Ionic OR (C) covalent

I A. sodium and oxygen

C B. nitrogen and oxygen

C C. phosphorus and chlorine

I D. calcium and sulfur

C E. chlorine and bromine


2. Diatomic Elements

• Elements that exist as atom pairs

• H2, O2, N2, Cl2, Br2, I2, F2,

• They are given the name of the element.

octets

N +

N N:::N triple bond



Use the name of the element to name a

diatomic molecules.

H2 hydrogen

N2 nitrogen

Cl2 _______________

O2 _______________

I2 _______________


Solution(COPY)

Use the name of the element to name the

following diatomic molecules.

H2 hydrogen

N2 nitrogen

Cl2 chlorine

O2 oxygen

I2 iodine


3. Binary Covalent CompoundsTwo nonmetals (def of binary covalent)1.Name each element 2.End the last element in -ide3.Add prefixes to show how many atoms of each

(except when there’s only 1 atom of the 1st element listed)

PREFIXES-COPY ONTO YOUR P. TABLEmono 1 hexa 6di 2 hepta 7tri 3 octa 8tetra 4 nona 9penta 5 deca 10



Fill in the blanks to complete the following names of covalent compounds.

CO carbon ______oxide

CO2 carbon _______________

PCl3 phosphorus _______chloride

CCl4 carbon ________chloride

N2O _____nitrogen _____oxide


Solution(COPY!)

CO carbon monoxide

CO2 carbon dioxide

PCl3 phosphorus trichloride

CCl4 carbon tetrachloride

N2O dinitrogen monoxide



A. P2O5 1) phosphorus oxide2) phosphorus pentoxide3) diphosphorus pentoxide

B. Cl2O7 1) dichlorine heptoxide2) dichlorine oxide3) chlorine heptoxide

C. Cl2 1) chlorine2) dichlorine3) dichloride


Solution(DON’T COPY)

A. P2O5 3) diphosphorus pentoxide

B. Cl2O7 1) dichlorine heptoxide

C. Cl2 1) chlorine

4. Hydrocarbons-A Type of Binary Covalent Compound

• Def: hydrocarbons are made of hydrogen & carbon

• They are named by the number of carbon atoms a molecule contains.

• They are important as fuels.

Hydrocarbons • The table below lists only hydrocarbons w/single

bonds• The names all end w/ “ane”

(COPY ONTO YOUR P. TABLE)

CH4 methane C6H14 hexane

C2H6 ethane C7H16 heptane

C3H8 propane C8H18 octane

C4H10 butane C9H20 nonane

C5H12 pentane C10H22 decane

Writing Formulas for Molecular Compounds

1. Analyze the name of the compound

2. Identify the type of compound (diatomic? binary? hydrocarbon?)

3. Reverse the process used to name it so you can determine the formula.


Tips for Identifying TYPE of Molecular Compound

IF THE NAME HAS: TYPE OF COMPOUND HOW TO WRITE

FORMULA

• Just the name of 1of • Diatomic Element • H2, O2, N2, Cl2,

the following elements: Br2, I2, F2

(HONClBrIF)

• Prefixes • Binary (2 elements) • Turn prefixes into

• Ends in “-ide” subscripts. (Write them after element symbol)

• Ends in “-ane” • Hydrocarbon • Look it up on list of hydrocarbons!LecturePLUS Timberlake 23

Common v. Formal Names

• Formal Names follow the rules we have learned for naming compounds.

• Common Names are ones that don’t follow these rules.

–Ex: water=

Frequently Used Common Names

• Water = H2O

• Ammonia = NH3


Covalent Bonds in NH3

(DON’T COPY)

Bonding pairs

H

H : N : H

Lone pair of electrons

Allotropes• Def: molecules of the same element that differ in

structure

• Ex 1: Carbon…graphite, charcoal, Buckminsterfullerine (“bucky ball”)=

C64

• Ex 2: O2 (oxygen) and O3 (ozone)

Q:Why do we have to specify the number of atoms of each element in

a covalent compound? (DON’T COPY)

A: Atoms of the same elements can combine in different ratios.

• Ex: C & OCOCO2

Writing Formulas for Covalent Compounds

1. Identify it as a covalent: containing only nonmetals.

2. Determine what type of covalent it is:

• diatomic element

• binary

• hydrocarbon (ends in –ane)

• acid/base

3. Reverse the naming process. LecturePLUS Timberlake 29

STOP HERE!!!


PLEASE NOTE:• IF YOU ARE UNABLE TO

IDENTIFY IONIC & COVALENT COMPOUNDS, YOU WILL BE LOST!!!

• PLEASE SEE ME IMMEDIATELY TO GET CAUGHT UP.


Naming Binary Ionic Compounds

1. Name the cation, which is the given the name of the element.

2. Name the anion, which is given the name of the element, w/the ending changed to “–ide.”


PRACTICE Naming Binary Ionic Compounds

1. Na║Cl

2. Na = “sodium”

3. Cl = “chloride”(full name is “sodium chloride”)


PRACTICE Naming Binary Ionic Compounds

1. Li2O

2 & 3.

____║____= ______ ______ (cation (anion (cation name) (anion name)

symbol) symbol)



Learning Check

Match each set with the correct name:

A. Na2CO3 1) magnesium sulfite

MgSO3 2) magnesium sulfate

MgSO4 3) sodium carbonate

B. Ca(HCO3)2 1) calcium carbonate

CaCO3 2) calcium phosphate

Ca3(PO4)2 3) calcium bicarbonate


Solution

A. Na2CO3 3) sodium carbonate

MgSO3 1) magnesium sulfite

MgSO4 2) magnesium sulfate

B. Ca(HCO3)2 3) calcium bicarbonate

CaCO3 1) calcium carbonate

Ca3(PO4)2 2) calcium phosphate


Learning Check

A. aluminum nitrate

1) AlNO3 2) Al(NO)3 3) Al(NO3)3

B. copper(II) nitrate

1) CuNO3 2) Cu(NO3)23) Cu2(NO3)

C. Iron (III) hydroxide

1) FeOH 2) Fe3OH 3) Fe(OH)3

D. Tin(IV) hydroxide

1) Sn(OH)4 2) Sn(OH)2 3) Sn4(OH)


Solution

A. aluminum nitrate

3) Al(NO3)3

B. copper(II) nitrate

2) Cu(NO3)2

C. Iron (III) hydroxide

3) Fe(OH)3

D. Tin(IV) hydroxide

1) Sn(OH)4

chemi/ih:chapter8 covalent bonding (click for video)

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