ch.20 - transition elements and coordination...

! www.clutchprep.com

!

CHEMISTRY - MCMURRY 7E

CH.20 - TRANSITION ELEMENTS AND COORDINATION CHEMISTRY

CONCEPT: THE TRANSITION METALS The transition metals represent elements found in the _____ – block of the periodic table.

Whereas the main group elements show similar chemical behavior because of their valence electrons, transition

metal similarities are treated differently.

• Transition metals show great chemical similarities in both their horizontal __________________ and their

vertical __________________.

• In the gradual addition of electrons to transition metals new electrons are added to the inner core electrons,

which do not participate in chemical bonding.

• For transition metals each additional electron is added to the _____ – block orbitals, while for lanthanides

and actinides they are added to the _____ – block orbitals.



CONCEPT: PROPERTIES OF TRANSITION METALS Like most main group metals the transition metals possess similar physical properties such as: luster , high

densities , good electrical and thermal conduction , _________ melting points and hardness.

Conduction

• _________ possesses the greatest electrical conduction with _________ coming in second.

Melting Point

• _________ possesses the highest melting point at 3400 oC, while _________ is the only metal that is a liquid

at room temperature.

Hardness

• Metals such as _________ and _________ are strong, but other metals such as _________ , _________

and _________ are considered soft.

Oxidation States

• Remember that transition metals possess variable charges and so the use of

__________________________ is necessary to identify the correct charge of the element.



CONCEPT: ELECTRON CONFIGURATION OF TRANSITION METALS Electron configurations are a representation of how electrons are distributed into orbitals and furthermore how those orbitals fit into different energy levels.

Recall there are exceptions that exist with the electron configuration of transition metals that end with _______ or _______.

• These exceptions are normally observed with only the _____________________ transition metals.

EXAMPLE: Write the condensed configuration for the following element:

Chromium (24 electrons)

1s2s$$$$$$2p3s$$$$$$3p$$$$$$3d4s$$$$$$4p$$$$$$4d$$$$$4f5s$$$$$$5p$$$$$$5d$$$$$5f$$$$$5g6s$$$$$$6p$$$$$$6d$$$$$6f$$$$$6g$$$$6h$7s$$$$$$7p$$$$$$7d$$$$$7f$$$$$7g$$$$7h



PRACTICE: ELECTRON CONFIGURATION OF TRANSITION METALS

EXAMPLE: Write the condensed electron configuration of the following element.

W

EXAMPLE: Write the condensed electron configuration of the following ion.

Mn4+

EXAMPLE: Write the condensed electron configuration of the following ion.

Fe6+



CONCEPT: TRENDS IN ATOMIC SIZE

Recall it ____________ going from left to right across a period and ______________ going down a group.

• For transition metals, when moving across a period the size for the most part remains constant.

Ex:

• When moving from the 3d transition metals to the 4d transition metals we see a (n) _____________ in atomic radius, but moving from 4d to 5d the pattern is quite different and stays relatively constant.

• This phenomenon is referred to as the lanthanide contraction.

e-

e-

e- e-

e-

e- e-

e-

e-

e-



CONCEPT: TRENDS IN IONIZATION ENERGY

Recall it ____________ going from left to right across a period and ______________ going down a group.

• However when moving down a group we see that the ionization energy of the third row is higher than the first and second row.

• This opposite trend is the result of the element’s _______________________________________.

e-

e-

e- e-

e-

e- e-

e-

e-

e-



CONCEPT: TRENDS IN OXIDATION STATES

As we’ve stated in the past oxidation involves _______________ electrons. • One of the most common features of transition metals is that they possess multiple oxidation states.

Ox. State

3B (3) 4B (4) 5B (5) 6B (6) 7B (7) 8B (8) 8B (9) 8B (10) 1B (11) 2B (12)

Sc Ti V Cr Mn Fe Co Ni Cu Zn 0 þ þ þ þ þ þ þ þ þ þ

+1 þ þ þ þ þ þ þ +2 þ þ þ þ þ þ þ þ þ +3 þ þ þ þ þ þ þ þ þ

+4 þ þ þ þ þ þ þ

+5 þ þ þ þ

+6 þ þ þ

+7 þ



PRACTICE: TRENDS IN OXIDATION STATES

EXAMPLE 1: Determine the oxidation state of the underlined element: [Ni(H2O)6]Cl2.

EXAMPLE 2: Determine the oxidation state of the underlined element: [Co(NH3)4(H2O)Br]Br2.

PRACTICE 1: In which compound does Ti exhibit greater metallic behavior: TiF2 or TiF6? PRACTICE 2: Which oxide, CrO3 or CrO, forms a more acidic aqueous solution?



CONCEPT: COORDINATION COMPOUNDS The most prevalent aspect of transition metal chemistry is the formation of coordination compounds or

complexes.

• Within a coordination complex there is at least one _______________________, a species that is made of a metal cation that is connected to molecules and/or anions called _______________.

• In order to maintain the overall neutrality of the compound, _______________________ are used.

COORDINATION NUMBERS

The coordination number is the number of ligand atoms bonded to the central metal cation.

• The coordination number is based on the _________ of metal cation and its _________________________.

• The most common coordination number is _____ , however 2 and 4 are also common.

GEOMETRIES

The types of geometries allowed are based on the coordination number of the central metal ion.

Coordination Number Shape

Linear

Tetrahedral

Square Planar

Octahedral

[Ni(NH3)4]Cl2

_______________________ _______________________ _______________________



PRACTICE: COORDINATION COMPOUNDS EXAMPLE 1: Determine the geometry for the following complex ion: [Zn(NH3)4]2+. EXAMPLE 2: Determine the geometry for the following complex ion: [AuBr2] –. PRACTICE: Determine the geometry for the following complex ion: [Cr(NH3)4Cl2]2+.



CONCEPT: LIGANDS A ligand can be thought of as a ___________________ because it bonds to a central metal cation in a complex ion by using its lone pair.

Ligands are characterized by the number of elements in the molecule that can donate a lone pair.

• These compounds use this lone pairs to grab onto these metal cations and are referred to as ____________________ agents.

Ligands that possess only _____ element(s) able to donate a lone pair are referred to as monodentate ligands.

Ligands that possess ________________ element(s) able to donate a lone pair are referred to as bidentate ligands.

Monodentate ("One-toothed")

H2O X C N HO

NH3 S C N

or

O N O

or

Bidentate ("Two-toothed")

CO

OC

O

O

2 –

H2C CH2H2N NH2



Ligands that possess ______________ element(s) able to donate a lone pair are referred to as polydentate ligands.

Polydentate ("Many-toothed")

CH2 CH2

NH NH2

H2C

H2CN N

CH2

CH2

H2C

H2C

C

C

C

C

O

O

O

O

O

O

O

O

4 –

Ethylenediaminetetraacetate ion (EDTA4 –)

H2CH2C

H2N

Diethylenetriamine

P

O

O O

O

P

O

O

O

P

O

O

O

5 –

Triphosphate ion



CONCEPT: NAMING COORDINATION COMPOUNDS In the early days of coordination compounds they were named after the person who first prepared them or for their brilliant colors.

• Today, the naming of coordination compounds is similar to naming ionic compounds.

Rules for Naming: a. The metal cation is written before the nonmetal anion.

• If the metal is a transition metal we must use a _________________________ to describe its positive charge. • The only space in the name should appear between the ___________ and the ___________ .

b. For the complex ion portion, neutral ligands are written before anionic ligands, and the formula for the whole ion is placed inside of brackets.

• Within the complex ion, the ligands are named in alphabetical order before the metal ion.

• Anionic ligands drop the – ide and add – o after the root name.

Neutral Ligands Anionic Ligands

Formula

Name \

Formula

Name

H2O Aqua Fluoro F – NH3 Ammine Chloro Cl – CO Carbonyl Bromo Br – NO Nitrosyl Iodo I – Hydroxo OH – Cyano CN –



c. A numerical prefix is used to determine the number of a particular ligand.

d. If the complex ion is an anion, we replace the ending of the metal name and add – ate.

Complex Anions

Metal

Name in Anion

Iron (Fe) Ferrate Copper (Cu) Cuprate Lead (Pb) Plumbate Silver (Ag) Argentate Gold (Au) Aurate Tin (Sn) Stannate

[Ti(NH3)4Br2]Br ________________________________________

Na[Pt(NH3)3Cl5] ________________________________________



PRACTICE: NAMING COORDINATION COMPOUNDS EXAMPLE 1: Give the systematic name for the following formula: Na[Ag(CN)2]. EXAMPLE 2: Give the formula based on the given name: Tetraamminezinc carbonate PRACTICE 1: Give the systematic name for the following formula: [Co(NH3)4(H2O)Cl]Cl2. PRACTICE 2: Give the formula based on the given name: Lithium bis(thiosulfato)argentate (I)



CONCEPT: STRUCTURE AND ISOMERISM Isomers are compounds that possess the same molecular formula, which means they have the same atoms, but they differ in their location of each atom.

ISOMERS_______ formula but ____________ structures

Different Connections

CONSTITUTIONAL ISOMERS

Coordination Isomers

Ligand and/or counterion swapping

Linkage Isomers

Difference in Donor Atom

Without Stereocenters

GEOMETRIC ISOMERS

Cis/Trans Isomers (Diastereomers)

Different spatial arrangements

With Stereocenters

OPTICAL ISOMERS

Enantiomers

Nonsuperimposable mirror images

Same Connections

STEREOISOMERS



ch.20 - transition elements and coordination...

Documents