Transition elements chp 24 Flashcards
what similarities do the d-block elements share
- all metallic
- display typical physical properties of metals
- high melting and boiling points
- shiny in appearance
- conduct both heat and electricity
what are some common uses for d-block elements
- tools, coins, construction
what is special about the electron configuration of chromium and copper
why is this
- they do not have full 4s orbtials
- its more stable to have a d5/d10 and 4s1 sub-shells than to have d4/d9 and 4s2 sub shells
what is unique about the 4s and 3d sub shells
- 3d is at a higher energy level than 4s
- 4s sub-shell fills up and empties before 3d sub-shell
what is the definition of a transition element
- d-block elements that form at least 1 ion with partially filled d-orbitals
which d-block elements are not transition elements
- scandium and zinc
- scandium only forms 3+ by losing its 4s electrons and its only 3d electron
- zinc only forms 2+ by the loss of its 4s electrons leaving it with a full 3d orbital
what are the properties of transition elements that differ from other metals
- transition elements have different oxidation States within certain compounds
- form coloured compounds
- elements and their compound can act as catalysts
what are the colours and oxidation states formed from the first period of d-block elements
what is the trend in number of different oxidation states across the transition elements
increase to manganese then decrease again
what are some examples of were transition metals and their compounds are used as catalysts
- iron catalyst in the haber process
- vanadium oxide catalyst in the contact process
- nickel in hydrogenation
what is a complex ion
- formed when one or more molecules or negatively charged ions bond to a central metal ion
what is the definition of a ligand
- a molecule or ion that donates a pair of electrons to a central metal ion to form a coordinate/dative covalent bond
what is meant by the coordination number
- indicates the number of coordinate bonds attached to the central metal ion
how should you represent complex ions
what is a monodentate ligand
- able to donate one pair of electrons to central ion
what are some examples of ligands and what would they be called in nomenclature
- water: aqua
- ammonia: ammine
- carbon monoxide: carbonyl
- cyanide ion: cyano
- chloride ion: chloro
- hydroxide ion: hydroxy
- oxygen molecule: oxo
- nitrogen monoxide: nitroso
what are bidentate ligands
ligands that can donate 2 lone pairs of electron to the central metal ion (forms 2 dative bonds)
what are some examples of bidentate ligands
- 1,2-diaminoethane (en)
- ethanedioate (oxalate)
what does the shape of a complex ion depend upon
- depends upon the coordination number
what shape does a complex ion with a coordination number of 6 have
octahedral shape
what 2 shapes can complex ions with coordination numbers of 4 give
- tetrahedral (common)
- square planar
when are square planar complexes formed
occur in complex ions of transition metals with 8 d-electrons in the highest energy d sub-shelled
what does the colour of the complex ions depend upon
- depends upon the metal at the centre of the complex, its oxidation state, and the ligands bonded to It
what types of steroisomerisms can complex ions display
- cis-trans isomerism
- optical isomerism
what does the type of stereoisomerism of complex ions depend on
- some 4 coordinate and 6 coordinate complex ions containing 2 different different monodenate ligands show cis-trans isomerism
- some 6 coordinate complex ions containing monodentate and bidentate ligands can show both cis-trans and optical isomerism
what is different between organic stereoisomerism and stereoisomerism in complex ions
- in organic, requires the presence of a C=C bond
- in complex ions, shape of complex holds groups in different orientations about central ion
when would cis isomer complex ions occur
- ligands are adjacent to one another
when would trans isomer complex ions occur
- ligands are opposite one another
on what octhedral complex can optical isomerism occur
has to contain 2 or more bidentate ligands
what is another name for optical isomers
- enantiomers
whats the definition of optical isomer
- non-superimposable mirror images of each other (like left hand and right hand)
what is a ligand substitution reaction
reaction is one in which one ligand in a complex ion is replaced by another ligand
when copper (II) sulphate is dissolved in water what is seen
pale blue complex ion [Cu(H2O)6] 2+, is formed
what happens when excess aqueous ammonia is added to a solution containing [Cu(H2O)6] 2+
- pale blue changes colour to form a dark blue solution
- 4 ammonia ligands have replaced 4 of the water ligands
if ammonia is added drop wise to a solution containing [Cu(H2O)6] 2+ what reactions and colour will be seen
- pale blue precipitate of Cu(OH)2 is formed in first stage
- Cu(OH)2 precipitate then dissolves in excess ammonia to for dark blue solution
what is seen when excess conc HCl is added to a solution containing [Cu(H2O)6] 2+
- pale blue solution changes to form yellow solution
- example of ligand substitution reaction
- 6 H2O molecules replaced by 4 Cl molecules
- Cl ligands are bigger than H2O ligands so fewer can fit round central ion
what is produced when chromium (III) potassium sulphate, KCr(SO4)2 - 12(H2O) is dissolved in water
- [Cr(H2O)6] 3+ is formed
^pale purple solution formed
what occurs when chromium (III) sulfate is dissolved in water
- green solution formed
- [Cr(H2O)5SO4]-
How does [Cr(H2O)6] 3+ reaction with excess ammonia
what can be observed
- forms complex ion [Cr(NH3)6]3+
- when excess added drop wise
^initally a grey-green precipitate of Cr(OH)3 is formed
^Cr(OH)3 dissolves in excess ammonia to form the complex ion [Cr(NH3)6] 3+
explain how carbon monoxide can effect haemoglobin
- When carbon monoxide is inhaled, it binds to hemoglobin to form carboxyhemoglobin
- this bond is much stronger than the bond between hemoglobin and oxygen.
- presence of carbon monoxide reduces the oxygen-carrying capacity of blood.
what is a precipitation reaction
- occurs when 2 aqueous solutions containing ions react together to form an insoluble ionic solid called a precipitate
how do transition metal ions aqueous solutions react with aqueous sodium hydroxide and aqueous ammonia
- they react by forming precipitates
- some of these will dissolve in excess sodium hydroxide or ammonia to form complex ions
what are some examples of precipitates that do not dissolve in excess of aqueous sodium hydroxide
Cu(OH)2, Fe(OH)s, Fe(OH)3 and Mn(OH)2 do not disssolve in excess sodium hydroxide
what can be seen when Fe2+ reacts with sodium hydroxide
write reaction
- pale green solution reacts to form green precipitate of iron (II) hydroxide
- precipitate is insoluble in excess sodium hydroxide but turns brown at its surface as Fe(II) is oxidised to Fe(III)
what can be seen as Fe 3+ reacts with sodium hydroxide
write reaction
- pale yellow solution reacts to form an orange-brown precipitate of iron (III) hydroxide
- precipitate is insoluble in excess
what can be seen if Mn2+ reacts with sodium hydroxide (NaOH)
write reaction
- pale pink solution reacts to form light brown precipitate of manganese hydroxide
- precipitate is insoluble in excess sodium hydroxide
what be seen if chromium (III) Cr3+ is reacted with (aq) NaOH
write reaction
- [Cr(H2O)6]3+ violet solution reacts to grey-green Cr(OH)3 precipitate
^is soluble in excess NaOH forms dark green [Cr(OH)6]3- solution
How does Fe 2+ react with MnO4 -
what colour is the reactants and products
How does Fe 3+ react with iodide ions
what colour are reactants and products
what type of reaction is the reaction of Cu+ with hot dilute sulfuric acid
- disproportionation reaction
what’s the test for transition metal ions
- aq NaOH producers precipitates with aq transition metal ions
