Transition metals Flashcards by Its Iman

Whats two key information you need to know on the d-block in the periodic table

1) Occupies the area between groups 2 and 3

2) Contains the transition metals

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What is a transition metal

A D-block element that forms one or more stable ions with incompletely filled d-orbitals

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Why are scandium and zinc not transition metals

Their ions do not have incompletely filled d-orbital:
All transition metals are d-block elements
.But not all d block elements are transition metals

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What can transition metals form

Complexes with ligands such as hydroxide ions and water

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What are complexes

Species containing a central metal ion surrounded by ligands bonded to it by dative bonds

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Whats a complex ion

Complexes with an overall positive or negative charge

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Whats a ligand

A species that can donate at least one pair of electrons to a metal ion, forming a dative bond

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Give examples of ligands

water/ ammonia or negative ions such as Cl- and OH-

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What is a coordination number

The number of dative bonds in a complex

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Whats a monodentate ligand

They can donate one lone pair of electrons to the central metal ion

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Whats a bidentate ligand

They can donate two lone pairs of electrons to the central metal ion

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What does the shape of a complex ion depend on

The number of ligands around their metal ions

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What are octahedral complexes

1) They contain six-fold coordination

2) Have an octahedral shape with bond angle 90 degrees

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How is a 3D formulae displayed

1) Solid lines - bonds in the plane of the paper
2) Dashed lines - bonds going behind the paper
3) Wedges - bonds coming out of the paper

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When are octahedral complexes usually formed

They are usually formed when the ligands are H2O, NH3, and OH-

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What are tetrahedral complexes

1) They have four-fold coordination
2) They have a tetrahedral shape with bond angles of 109.5
3) They usually formed when ligands are relatively large such as Cl-

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What are square planar complexes

1)Contain 4 ligands
2)90 degrees
3)an example is [PtCl2(NH3)2]
it has two stereoisomers

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What does the systematic name for a complex ion tell you

1) The number and identity of each ligand
2) The identity of the central metal ion and its oxidation number
3) Whether the complex ion is positively charged or negatively charged

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How do transition metals form coloured ions in solution

Due to the splitting of the energy levels of their d-orbitals

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What happens when an atom or ion absorbs light

An electron is promoted from its normal ground state to a higher excited state

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What is an electron transition

A change from one energy level to another

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What does the frequency of light absorb depend on

The energy of the transition

The greater the energy of the transition, the higher the frequency of the light absorbed

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What happens when white light passes through a solution

Some frequencies of light may be absorbed

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What are the colors emerging from the solution called

complementary colors

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What happens when ligands bond with a transition metal ion What does this lead to

electrons in the ligand and electrons in the d-orbital repel each other As a result 1) the energy levels of the d-orbital increase 2) Two slightly different energy levels form 3) A d electron can be promoted forms lower level tithe high level, f this is partially occupied

What happens when light passes through a solution

Because transition metal ions have incompletely filled d-orbital, Energy in the light promotes an electron from a lower level to a higher level

Why do the d-orbitals in metal ions in octahedral complexes split

to produce two d-orbitals at a higher energy level

Why do the d-orbitals in metal ions in tetrahedral complexes split

To produce three d-orbitals at a higher energy level

What may be a reason why a colour change in transition metal ions may occur

Because of the change in oxidation number, ligand or coordination number

What happens the higher the oxidation number in a given transition metal ion

1) The greater the amount of splitting of the energy levels of the d-orbital by ligands 2) The greater the energy level difference becomes

What do different ligands cause

Different amount if splitting of the energy levels of the d-orbital

What's the trend of the amount of splitting of the energy levels of d-orbitals in different ligands

When the splitting increases the energy level difference increases

What is haemoglobin

It is an iron (II) complex containing a multidentate ligand

What two things can because the carbon atom has a lone pair of electrons

1) Carbon monoxide can act as a ligand | 2) It binds to haemoglobin more strongly than oxygen does

What do coordination numbers affect

An ions colour

What is the coordination of: a) Tetrahedral b) Octahedral

a) 4 | b) 6

Which one out of tetrahedral and octahedral has the most: a) splitting b) Energy level difference

a) Octahedral | b) Octahedral

What colour is formed of: a) Octahedral [Co(H2o)6]2+ b) Tetrahedral [Co(H2o)4]2+

a) Blue | b) Pink

What reduces vanadium

by zinc in acidic solution from +5 to +2

What is the colour, formulae and oxidation number of: a) Dioxovanadium (V) b) Oxovanadium(IV) c) Vanadium (III) d) Vanadium (II)

``` a)Yellow VO2+ (lower case 2) +5 b)Blue VO2+ (power of 2) +4 c)Green V3+ +3 d)Purple V2+ +2 ```

What's the colour change we see as dioxovanadium (V) is being reduced to vanadium (II) using Zinc

1) Yellow to blue (+3 to +4) 2) Blue to green (+4 to +5) 3) green to purple (+3 to +2)

What is the colour formulae and oxidation number of: a) Chromate (VI) b) dichromate (VI) c) Chromium (III) d) Chromium (II)

``` a)Yellow CrO42- +6 b)Orange CrO72- +6 c)Green Cr3+ +3 d)Blue Cr2+ +2 ```

What is used to reduce Chromium (VI) to Chromium (II) using

Zinc with sulfuric or hydrochloric acid

What do you see when Chromium (VI) is being reduced to Chromium (II)

Colour change 1) Orange to green (+6 to +3) 2) Green to blue (+3 to +2)

What do transition metals ammonia undergo and what do they form

acid-base reactions | Form precipitates

What do M2+ ions and NH3 produce

Produce coloured precipitates

Why is the reaction between M2+ and NH3 acid-base

1) NH3 acts as a Bronsted-Lowry base | 2) But the precipitate is identical to those formed by reaction with OH- ions

Chromium (III) hydroxide is amphoteric | What does this mean

It acts as both an acid and as a base

Whats ligand exchange accompanied by

A colour change and may lead to a change in coordination number

What complex is copper (II)

Octahedral complexes | Coordination number 6

How does hexaaquacopper (II) [Cu(H20)6]2+ form Tetraaquahydroxocopper (II) [Cu(H20)4(OH)2] What's the color change What's the colour change due to

By adding NaOH or NH3 pale blue to blue presence of different ligands

``` How does Tetraaquahydroxocopper (II) [Cu(H20)4(OH)2] form tetraamminediaquacopper (II) [Cu(NH3)4(H20)2]2+ ``` Whats the colour change What's the colour change due to

Add excess NH3 (aq) blue to deep blue presence of different ligands

When can a change in coordination number happen in tetrahedral complexes

If small, uncharged ligands such as H2O are replaced by larger, charged ligands such as Cl- ions

What's the color change from [Cu(H20)6]2+ to [CuCl4]2- as the coordination number goes from 6 to 4

pale blue to yellow

What's the color change from [Co(H20)6]2+ to [CoCl4]2- as the coordination number goes from 6 to 4

Pink to blue

In the tetrahedral complexes what did not change and what did change

Oxidation number | Coordination number and ligands change

What is a heterogeneous catalyst

A catalyst that is in a different phase from the reactants

Give examples of heterogeneous catalysts and what they're used for

a) Iron - the Haber process b) Vanadium (V) oxide, V2O5 - The contact process c) Nickel - addition reactions of alkenes with hydrogen d)platinum - Catalytic converters

How is sulfuric acid manufactured

By a contact process

What are the three main steps in the action of a heterogeneous catalyst

1) Adsorption of one or more reactants on to the surface of the catalyst 2) Weakening of bonds in the reactants followed by reaction 3) Desorption of products from the surface

What are catalysts poisoned by

by impurities that absorb strongly on to their active sites on the surface, blocking the adsorption of reactants

What is a homogeneous catalyst

A catalyst that is in the same phase as the reactants.

What happens when charged reactants repel each other

1) Leads to a higher activation energy, Ea, and | 2) A low rate of reaction at room temperature

What are the two steps for the reaction of S2O82- + I- that's catalyzed by Fe2+

1) Reaction between Fe2+ and S2o82- | 2) Reaction between Fe3+ and I-

What's the overall reaction between S2O82- + I-

S2O82- (aq) + 2I- (aq) ---> 2SO42-(aq) + I2 (aq)

Transition metals Flashcards

(65 cards)