chem unit4

IonsCations

X ---> X+

When atoms lose electrons

AnionsX -----> X-

When atoms gain electrons

Both form ions isoelectronic with noble gas atoms

NaCl (Table Salt)

Na+ + Cl- --> NaCl

Iodized Table Salt

• Iodide added to prevent goiter

NaCl

With some NaI

Na+ + I- ---> NaI

Salt Products

Ion CombinationsCations Anions

Mix and Match!

Ionization Energy

Alkaline Earth Elements• Be ----------> Be2+

loses 2 electrons1s22s2 1s2

isoelectronic with He

Mg2+

Ca2+

Sr2+

Ba2+

Chalcogens

Possible Ion Combinations

Name that Salt

• Cation first, then Anion

• Cation name is SameAnion: drop ending, add –ide

RbF

SrSe

Name that Salt

• Cation first, then Anion

• Cation name is SameAnion: drop ending, add –ide

RbF rubidium fluoride

SrSe strontium selenide

Stable Transition Metal IonsGroup 4

Group 5 Group 6 Group 7 Group 8

Group 9 Group 10 Group 11

Group 12

Group 13

Group 14

Ti2+

Ti3+

V2+

V3+

Cr2+

Cr3+

Mn2+

Mn3+

Fe2+

Fe3+

Co2+

Co3+

Ni2+ Cu+

Cu2+

Zn2+ Ga2+

Ga3+

Ge2+

Mo3+ Tc2+ Pd2+ Ag+

Ag2+

Cd2+ In+

In2+

In3+

Sn2+

Hf4+ Re4+

Re5+

Pt2+

Pt4+

Au+

Au2+

Hg2+ Tl+

Tl3+

Pb2+

Name the (transition metal) salt

• Cation first, anion next

• List the charge of the metal as a Roman numeral:

• e.g. FeCl3 is iron (III) chloride

but FeCl2 is iron (II) chloride

Polyatomic Ions

Ions composed of more than one atom

Ion Name Ion Name

NH4+ Ammonium CO3

2- Carbonate

NO2- Nitrite CN- Cyanide

NO3- Nitrate C2H3O2

- Acetate

OH- Hydroxide O22- Peroxide

SO32- Sulfite SO4

2- Sulfate

ClO- hypochlorite ClO3- Chlorate

ClO2- Chlorite ClO4- Perchlorate

PO43- Phosphate BrO3

- Bromate

AsO43- Arsenate CrO4

2- Chromate

Naming Polyatomic Salts

• Calcium Carbonate

Naming Polyatomic Salts

• Calcium Carbonate

Ca2+ CO32- CaCO3

Naming Polyatomic Salts

• Potassium Chlorate

Naming Polyatomic Salts

• Potassium Chlorate

K+ ClO3- KClO3

Naming Polyatomic Salts

• Calcium Phosphate

Naming Polyatomic Salts

• Calcium Phosphate

Ca2+ PO43-

Naming Polyatomic Salts

• Calcium Phosphate

3 Ca2+ 2 PO43- Ca3(PO4)2

Naming Polyatomic Salts

• NH4NO3

Naming Polyatomic Salts

• NH4NO3

Ammonium Nitrate

Naming Polyatomic Salts

• Magnesium hydroxide

Naming Polyatomic Salts

• Magnesium hydroxide

• Mg2+ OH- Mg(OH)2

Properties of Salts

• Fracturing

Properties of Salts

• High melting and boiling points

Salt Melting Point Boiling Point

NaI 660 1304

KBr 734 1435

NaBr 747 1390

CaCl2 782 >1600

NaCl 801 1413

MgO 2852 3600

Properties of Salts

• Conductivity

Salt Crystal Lattices are broken up by water molecules

So solutions of salts conductHeat and electricity

What about the others???

Organic Chemistry

• Carbon Chemistry

Carbon atom

Lewis dot Structures

Gilbert Lewis (UCBerkeley)

Covalent Bonds

• Shared electrons

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Lewis Dot Rules

• H2O

• Number of valence for single atom• Number of valence electrons for

other atom• Organize electrons in pairs optimally

to reach an OCTET

electrons for the minority atom

Lewis Dot Rules

• H2O

• Number of valence for Oxygen (6)• Number of valence electrons for H (1)• Organize electrons in pairs optimally

to reach an OCTET

Ammonia

• NH3

• N: 5 valence electrons• H: 1 valence electron

Methane

• CH4 (natural gas)

• Carbon: 4 valence electronsHydrogen: 1 valence electron

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Methane

• CH4 (natural gas)

• Carbon: 4 valence electronsHydrogen: 1 valence electron

Ethylene

• C2H4

• Carbon: 4 valence electronsHydrogen: 1 valence electron

Ethylene

• C2H4

• Carbon: 4 valence electronsHydrogen: 1 valence electron

Acetylene

• C2H2

H:C:::C:H triple bond

Diatomic Molecules• O2

• Each oxygen atom has 6 valence electrons

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Diatomic Molecules• O2

• Each oxygen atom has 6 valence electrons

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Nitrogen Gas

• N2

• :N:::N:

• N=N triple bond

• Very inert in nature

Naming Covalent Compounds

• Two words

• Name in order of formula appearance

• Example: SF4

• Sulfur tetrafluoride

45

Naming Covalent Compounds

• Two words

• Name in order of formula appearance

• Example: N2O5

• dinitrogen pentaoxide (pentoxide)

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Electronegativity

47

Electronegativity Values

48

Bond Polarity

Bonding Spectrum

Water: Polar Covalent

• Why does water (a covalent molecule)dissolve NaCl salt crystals?

Water: Polar Covalent

• Why does water (a covalent molecule)dissolve NaCl salt crystals?

• Water is a dipolar molecule (polar)

CO2: Non-polar

CO2 has 2 C=O dipoles

Two opposite dipoles cancel out

VSEPR

• Valence Shell Electron Pair Repulsion

• Predicting the shapes of covalent molecules

VSEPR Rules• Draw the Lewis Structure (octet rule)

• Count the number of electron clouds (single bond = 1; each multiple bond = 1

each nonbonding electron pair = 1)•

linear = 2 clouds• Apply correct geometry trigonal planar = 3

tetrahedral = 4• Adjust bond angles (for nonbonded electrons)

Water

• H2O

why is it drawn with a bent shape?

# of electron clouds = 2 nonbonded+

2 O-H bonds = 4

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Boron Trifluoride

• BF3

TRIGONAL PLANAR• Exception to the octet rule