CHE 2C Midterm 1

Oxidizing Agent

oxidizes compounds or elements in a reaction. the species that is reduced

Reducing Agent

the species oxidized in a reaction. reduces compounds or elements in a reaction

Anode

where oxidation occurs, drawn on the LHS, e- flow, pitting, corrosion (metal→ore)

Cathode

where reduction occurs, drawn on the RHS, current, plating, refining (ore→metal)

Where do electrons flow?

from the anode to the cathode

Standard Hydrogen Electrode (SHE)

assigned 0.00V, a standard

What happens when a half reaction is multiplied by a constant?

E^o does not change

E>0

spontaneous reaction, shift towards products

E<0

nonspontaneous reaction, shift towards reactants

E=0

equilibirum, no shift

Concentration Cells

consists of two half cells having the same reaction but only differ in concentrations

E=0

The reaction is driven forward if the molarity of the cathode>anode

Spontaneous

deltaG<0

E>0

Nonspontaneous

deltaG>0

E<0

Equilibrium

deltaG=0

E=0

K=Q

Primary Cell

reaction is non-reversible. battery eventually goes dead

Dry Cell

• hold charge a long time, good for emergency use

• zinc is the anode, manganese oxide is cathode, sometimes mercury

• can be acidic or alkaline

Button Battery

• high storage capacity, very small

• Anode=zinc

• cathode=silver

Secondary Cell

reaction can be reversed

Lead-Acid (Storage) Battery

• concentration cell

• can be put together to make car batteries

Nickel-Cadmium or Ni-CAD batteries

• home use rechargable batteries

• Anode: Cadmium

• Cathode: Nickel

Lithium Battery

• very reliable, long lifetimes

• high capacity

• Anode: Lithium

• Cathode: Lithium + Cobalt

Flow/ Fuel Cell

• reactants, products, and electrolytes pass through a converter of chemical→electrical energy

• fuel cells are fueled by oxidation + water, very spontaneous

• air batteries

Corrosion

process of returning a metal to it’s natural ore state, oxidation of the metal. essentially an unwanted Galvanic Cell. Rust is an example, however, Fe flakes off while most other metals create a protective coating when oxidized

Cathode Protection

a way to control corrosion of a metal, by attaching a sacrificial anode that will oxidize before the metal, like a coating

Plating

the technique of adding a sacrificial anode onto another metal

Alloy

a mixture of metals that may or may not be homogenous

Electrolysis (electrolytic cell)

the process of making nonspontaneous reactions happen by electricity or a battery

• used to collect and plate metals

Electrorefining

deposition of a pure metal at a cathode from a solution containing the metal ions

Electroplating

one metal is plated onto another (less expensive)

Transition Metal Radii

• generally decrease then increase across the row

• this is due to increased electron-electron repulsion

Lanthanide Contraction

• the second and third row of radii are nearly the same for lanthanides. the f-electrons of lanthanides don’t shield the nucleus well, leading to contraction

• also results in higher density of the third row

What happens when transition metals are oxidized by losing electrons?

they become cationic

transition metals hold multiple oxidation states b/c they can lose electrons from d & s shells

Notable Weird TMs

Cr = [Ar]4s^1ed^5 (4th column)

Mo = [Kr]5s^14d^5 (4th column)

Cu = [Ar]4s^13d^10 (9th column)

Ag = [Kr]5s^14d^10 (9th column)

Transition Metals Character

have both ionic and covalent characters

their covalent bonds are typically coordinate covalent

Transition Metals colors

anything with partially filled d-shells have color

unfilled and filled d-shells are colorless

Transition Metals Metallicness

most are paramagnetic, some are ferromagnetic

Why are Transmission Metals good catalysts?

• multiple oxidation states and coordination numbers are possible

• ligands can easily bond and multiple bonding sides are availiable

• transition metals can generally accept more ligands

Metallurgy

the process of refining metal ore into a pure metal

Scandium Family

Scandium

• common ox. states: 3+/d^0

• colorless

• diamagnetic

• similar properties as ytrium and aluminum

• ytrium is actually 4 elements of the same name

Titanium Family

Titanium

• low density, high strength

• common ox. states: +3/d^1 , +4/d^0

Zirconium + Hafnium

Vanadium Family

vanadium

• very strong and tough

• common ox. states +5/d^0 , +2/d³

Nidium + Tanatulum

Chromium Family

chromium

• corrosion resistant

• great for plating

• common ox. states +2/d^4 , +3/d³ , +6/d^0

Molybdenum

Tungsten

• makes hard materials

• in filaments in incandescant bulbs

Manganese Family

Manganese

• used in primary cell batteries

• great catalysts

• common ox. states +2/d^5…+7/d^0

Techetium

• radioactive

rhenium

Iron Family

Iron

• very important

• in basically everything

• common ox. states +2/d^6 , +3/d^5

Ruthenium + Osmium

Cobalt Family

Cobalt

• forms strong M-CO bonds

• can change lots of colors

• common ox. states +2/d^7 , +3/d^6

rhodium

iridium

Nickel Family

Nickel

• corrosion resistant→ does not oxidize

• NiCAD battery cathode

• extremely stable (double magic)

• metal carbonyl bonds

• Common ox. states +2

Paladium

• great catlyst

• Jewelry

Platinum

• THE catalyst

• jewelry

• common ox. states +2 , +4

Copper Family

Copper

• recyclable

• common alloys: brass(+Zn) and bronze(+Sn)

• Common ox. states +1 , +2

Silver

• oxidize=tarnish

• common alloys: sterling silver(+cu)

• jewelry, coin, photofilm, tech-fillings, battery

• button battery cathode

Gold

• does not oxidize, corrosion resistant

• jewelry

• malleable

Zinc Family

Zinc

• used to galvanize

• corrosion resistant

• dry cell anode, button battery cathode

• colorless

• common ox. state +2/d^10

Cadmium

• NiCad battery anode

• common ox. state +2

Mercury

• quicksilver

• hydragyrum

• only metal a liquid at STP

• common ox. states: +1/Hg2^+2 , +2/Hg²+

Lanthanides + Actinides family

inner transition metals

most common ox. state ; +3

Coordination Compound

formed from transmission metal ions, in combination w/ligands & counter ions, general term for neutral compounds that contain transition metals

[Co(NH3)5Cl]Cl2

Complex Ions

Transition metal ions w/ ligands when the transition metal species has a nonzero charge

[Co(NH3)Cl)²+

Counter Ions

anions or cations needed to produce a compound with no net charge, added to make a complex ion a neutral coordination compound

Ligands

groups (not including counter ions) that surround the transition metal ions, typically donates a lone pair, neutral or negative charge

Coordination Number (CN)

the number of nearest neighbors to the transition metal ion. typically ligands, in the brackets

Complex

general term for any species involving ligands connected to a TM ion

Oxidation State

primary value of the TM

monodentate

a ligand w/ one pair of electrons to attach (bond) to TMs

polydentate(chelating)

A ligand with 2 or more pairs of electrons to attach (bond) to the TM

H2O ligand

Aqua

Neutrals, monodentate

NH3 Ligand

Ammine

neutral, mondentate

CO Ligand

carbonyl

neutral, mondentate

NO Ligand

nitrosyle

neutral, mondentate

CH3NH2 ligand

methylamine

neutral, monodentate

C5H5N ligand

pyridine

neutral, monodentate

F- Ligand

Fluro

anion, monodentate

Cl- Ligand

chloro

anion, monodentate

Br- Ligand

brono

anion, monodentate

I- Ligand

Iodo

anion, monodentate

O²- Ligand

oxo

anion, monodentate

OH- Ligand

hydroxo

anion, monodentate

CN- ligand

cyano

anion, monodentate

SO4²- Ligand

sulfate

anion, monodentate

S2O3²- Ligand

Thiosulfate

anion, monodentate

NO2^- Ligand

Nitrito-N-

anion, monodentate

ONO^- Ligand

Nitritio-O-

anion, monodentate

SCN^- Ligand

thiocyanato-S-

anion, monodentate

NCS^- Ligand

Thiocyanato-N-

anion, monodentate

en Ligand

ethylenediamene

polydentate

ox²- , ox, or C2O4²- Ligand

oxalate ion

polydentate

acac Ligand

acetylacetonate ion

polydentate

EDTA^4- or EDTA Ligand

ethylenediaminetetracetato ion

polydentate

Composite Ligands

ligands that contain a prefix in it’s name need composite prefixes.

ex: EDTA, en (mostly), but NOT ox

-bis = -Di

-tris = -tri

-tetrakis = -tetra

Central Dogma for Complex Ions

• ligands first in alphabetical order (not including prefixes)

• metal with oxidation state in roman numerals is last

• if complex ion is anion the metal must be named in latin w/ -ate suffix

• if complex ion is a cation, the metal is named in English w/ no additional suffix

• if there is a counter ion the cation is named first

• if no counter ion, ion is the last name

Iron Latin

ferrate

Copper Latin

cuprate

Tin latin

Stannate

Silver Latin

Argenate

Lead Latin

Plumbate

Gold Latin

Aurate

Ionization isomers

where a ligand and counter ion switch

structural isomer

Coordination isomers

where the TMs of a bimetallic (2 metal) species switch ligands

structural isomer

Linkage isomers

where a multi-atom ligand connects to the transition metal through different atoms

structural isomer

Sterioisomers

a different arrangement of atoms in space

Geometric isomers

where the arrangement of the ligands are either neighboring(cis or fac) or across (trans or mer) from eachother

trans

2 identical ligands are bonded directly across from each other

exists in square planar or octahedral

cis

2 identical ligands are bonded neighboring each other

exists in square planar or octahedral

could possibly be chiral

fac

when 3 identical ligands are bonded on 3 different axises

exists in octahedral

could possibly be chiral

mer

occurs with 3 identical ligands, 2 of them are bonded on the same axis

exists in octahedral

optical isomers

where the arrangement of atoms results in a non-superimposable mirror images

• known experimentally to rotate plane, polarized light

• called chiral or optically active

enantiomers

the optical isomer and it’s ‘mirror’ image