| What are the features of the d block elements? (7) | transition metal elements that have different oxidation states
forms complex ions w/ ligands
colored compounds
act as catalysts
can have magnetic properties
smaller variation of IE and AR
High MP and densities |
| Why is zinc not considered to be a transition element? (3) | because it doesn't form ions with incomplete d orbitals
can only form a +2 ion which has a full d shell
can't form colored compounds |
| What oxidation state do all transition elements have? | +2 |
| Why are the transition elements called d block elements? | bec the subshell being filled across this series is the 3d subshell |
| What is a transition element? | an element that forms at least 1 stable ion with a partially filled d subshell |
| Which electrons are removed first from these elements? | the 4s electrons because it has a lower energy than 3d |
| Where is the greatest number of different oxidation states found and why? | middle of the series (manganese) because there is an increase in the total no of electrons in the 4s and 4d subshells |
| Why does the number of oxidation states decrease after manganese? | bec the IE increases along the period so it is more difficult to have more oxidation states |
| How can transition metals have more than one oxidation state? | bec the 4s and 3d subshells are close in energy = no big jumps in IE when the 4s and 3d electrons are removed
= successive ionization energies |
| What does the no of electrons lost depend upon? (3) | lattice enthalpy
ionization energy
hydration enthalpy |
| What are the two types of magnetism? | paramagnetism
diamagnetism |
| What is paramagnetism? | caused by unpaired electrons = attracted by a magnetic field
has a larger effect than diamagnetic so if there are any unpaired electrons in a substance = it will be attracted by a magnetic field
more unpaired electrons == more paramagnetic |
| What is diamagnetism? where can it be found? (3) | caused by paired electrons = repelled by a magnetic field slightly
all substances have some paired electrons so all substances show diamagnetism
but has a smaller effect than paramagnetic |
| What are complex ions composed of? | central metal ion surrounded w ligands |
| What is a ligand? | negative ions / neutral molecules that have lone pairs of electrons
form coordinate covalent (dative) bonds with the metal ion
lewis base
the ligand donates lone pairs into the empty orbitals of 3d, 4s or 4p on the transition metal ion |
| What geometry do all transition elements form? exception? | octahedral except titanium
formula = [M(H2O)6]2+ in aqueous solution |
| general formula of a complex ion in an aqueous solution? | [M(H2O)6]2+ |
| What are the possible charges for a ligand? | neutral or negative |
| how can the oxidation number of the transition metal in a complex ion be worked out? | with the charges of the ligands |
| What is an example of a transition metal being a catalyst? | iron is a catalyst in the haber process to produce ammonia
transition metal compounds usually act as homogenous catalysts (same phase as the catalysts |
| What does the ability of performing as a catalyst depend upon? | the transition metal atom or ion needs varying oxidation numbers
need to be able to coordinate with other molecules / ions to form complex ions |
| What happens to the 3d orbital when a transition metal is in a complex ion? | usually they have the same energy (degenerate)
but when surrounded by ligands = d orbital splits into 2 groups
lower group = 3 orbitals
higher group = 2 orbitals |
| What is the difference between the d orbitals in a complex ion and in an isolated gaseous ion? | all the d orbitals in a complex ion are higher in energy than the d orbitals of a gaseous ion |
| Why do the d orbitals split in a complex ion? | because of the repulsion bw the electrons in the metal ion d orbitals and the lone pairs from ligands
2 d orbitals point towards the ligands = repelled more by the ligand's electrons = greater repulsion = higher energy |
| How can electron from the lower set be promoted to the higher set d orbital? | energy as visible light can be absorbed to from an electron |
| what is the difference bw the color that is emitted and the color that is absorbed? | the colors are complementary |
| What does the formation of a colored substance require? | a partially filled d subshell |
| What are some examples of transition metal ions that wont be colored and why? | Sc3+ and Ti4+ ions have no electrons in the 3d subshell so they are colorless
= they can't absorb energy to promote a 3d electron
Cu+ and Zn2+ have 10 3d electrons = no space in the upper set of d orbitals so it isn't possible to promote an electron = no light in the visible region is absorbed = colourless |
| What is the main factor that affect the color of transition metal complexes? | related to the amount of splitting of the d orbitals = if ther eis a greater energy difference bw the lower and higher set of the d orbitals = higher F (shorter WL) = diff complementary color |
| What are different factors that could affect the color of the transition metal complexes? | the metal
oxidation number
nature of the ligand |
| How does the identity of the metal affect the color of the complex ion? | different metal ions have diff electron configurations
= colors are caused by electron transitions
= diff arrangements of electrons
= diff colors bec of diff amount of repulsion bw electrons |
| How can we deduce which complex ion will have greater splitting of the 3d orbital if they have the same number of electrons? (5) | the complex ion with the higher nuclear charge on the metal ion
= bec it causes the ligands to be pulled in closer to the metal ion
= greater repulsion bw the ligand electrons and the d electrons of the metal ion
= greater splitting of the d orbitals
EG: [Mn(H2O)6]2+ and [Fe(H2O)6]3+ both have 5 3d electrons = greater splitting in the Fe ion bec it has 26+ |
| What does isoelectronic mean? | same number of electrons |
| How does oxidation number cause different colors of complex ions? (4) | different electron configuration
higher charge on the metal ion = ligand is pulled in more closely
greater repulsion bw the ligand electrons and d electrons
= greater splitting of d orbitals |
| How do different ligand cause different colors of complex ions? | bec of the different splitting of the d orbitals caused by different ligands |
| the ligands that cause greater splitting in the d orbitals are called? | stronger field ligands |
| What is the order of ligands from weakest - strongest? | I- , Br-, Cl-, F-, OH-, H2O, NH3, CO, CN- |
| What does a larger energy gap mean for the energy absorbed? | shorter wavelength
higher frequency |
| Why does the F- ligand cause greater spitting than the I- ligand? | due to charge density
charge per unit volume
although F and I have the same charge, the F- is smaller
= greater repulsion of the metal ion d electrons
= greater splitting of the d orbitals |
