Flashcards in Module 5.3 Deck (16)
When writing down the electronic configuration of a Period 4 d-block element, what must you consider?
The fact that 4s electrons fill up before 3d electrons (they're lower in energy level)
What is a transition element?
A d-block element that can form at least ONE STABLE ION with an INCOMPLETE d sub-shell
When transition element ions are formed, which electrons are removed first?
The S ELECTRONS are removed first, then the d electrons
State the electronic configuration of Fe, Fe2+ and Fe3+
Fe = 1s2 2s2 2p6 3s2 3p6 3d6 4s2
Fe2+ = 1s2 2s2 2p6 3s2 3p6 3d6
Fe3+ = 1s2 2s2 2p6 3s2 3p6 3d5
Why is Scandium not a Transition Element?
Scandium only forms Sc3+ which has an EMPTY d sub-shell (remember the definition of a transition element)
Why is Zinc not a Transition Element?
Zinc only forms Zn2+ which has a FULL d sub-shell (remember the definition of a transition element)
Why do transition elements exist in variable oxidation states?
Because the energy levels of the 4s and 3d sub-shells are very close to one another.
So different numbers of electrons can be gained or lost using fairly similar amounts of energy.
In terms of oxidation states, why can transition elements and their compounds make good catalysts?
Because they can change oxidation states by GAINING or LOSING electrons within their d-orbitals.
This means they can transfer electrons to speed up reactions.
Why do Transition METALS make good catalysts?
Because they are good at adsorbing substances onto their surfaces to lower the activation energy of reactions
Why are catalysts, like transition elements/metals, good for the industry and the environment?
They allow reactions to happen FASTER and at LOWER temperatures and pressures, reducing energy usage.
Why can transition element catalysts pose health risks?
Many of the metals and their compounds are TOXIC, e.g. Copper can damage the liver and kidneys, manganese can cause psychiatric problems
What happens when you mix a transition element ION with aqueous Sodium Hydroxide (NaOH) or aqueous Ammonia (NH3)?
You get a COLOURED HYDROXIDE PRECIPITATE
What form do transition elements take in aqueous solutions?
(if the metal is bonded to water, you may write it out as M^n+, but anything else = full formula)
Express the ionic equation for the reaction between aqueous Copper(II) ion and NaOH (OH-).
[Cu(H2O)6]2+ (aq) + 2OH- (aq) → [Cu(OH)2(H2O)4] (s) + 2H2O (l)
This can also be written as: Cu2+ (aq) + 2OH- (aq) → Cu(OH)2 (s)
Express the ionic equation for the reaction between aqueous Copper(II) ion and NH3.
[Cu(H2O)6]2+ (aq) + 2NH3 (aq) → [Cu(OH)2(H2O)4] (s) + 2NH4+ (l)