Chapter 24 TRANSITION ELEMENTS Flashcards
Why are d block elements called them again
Because the highest energy sub shell is thr D sub shell
What are the TWO EXCEPTIONS to electron filling in the D block elements
Why?
Chromium 3D5 4s1
Copper 3D10 4s1
Believed to give more stability : half filled 3d5 and full filled 3d10 is more stable then without
What are transition elements DEFINITION
This is elements that form at least one ion with a PARTIALLY FULL D SUB SHELL
So why are scandium and zinc not considered transition elements, even tho are in the d block?
What ions they form?
Because scandium IONS has no electrons in d orbitals, and zinc IONS has full electrons in d orbitals
Definition = partially full d orbitals when ions made, thus not transition
2) sc = sc 3+, Zn = Zn2+
What are the 3 characteristic properties of transitions metals and their compounds?
1) form compounds where the transition element can have DIFFERENT OXIDATION STATE
2) Form COLOURED COMPOUNDS
3) Elements and compounds can act as CATALYSTS
What happens when a transitions metal changes it’s oxidation state
It’s colour changes.
For example chromium cr3+ is green and cr6+ is orange
So in dichromate test it goes from orange to green as it gets reduced , as it itself is an oxisising agent
What oxidation state can all the transition elements take at least
+2 each time, some more
Colours of IRON 2 and Iron 3, and chromium 3 and 6 in solution
IMPORTANT= THESE COLOURS ONLY SHOW IN WHAT FORM
Iron 2 = pale green
Iron 3 = yellow
Chromium 6 = orange
Chromium 3 = green
(Remember chromium is oxidising agent so it becomes reduced, and gains electrons, so oxidation number goes down)
2) ONLY SHOW WHEN IN SOLUTION THUS AQEUOUS! NOT AS A COMPOUND
3 examples of catalysts of transition metals
Haber
Contact
Zinc
Haber process
N2 +3H2 —> 2Nh3 uses IRON CATALYST
Contact process
2So3 + o2 —> 2So3
Uses V2O5 (S)
Zinc and acid
Zn + h2so4 —> ZnSo4 + H2
CU 2+ IONS
Homo heterogenous catalysts again
Homo is same state, hetero different like contact and Haber process
What are the benefits of a catalyst again
SPEC ANSWER (2)
- reduced energy usage
- reduced risks of toxicity from the transition metals
What is a complex ion
What is a LIGAND
What is the coordination number!
When one more ligand binds ti a central metal ion
A ligand is a molecule or ion that has a lone pair and donates it to the central metal ion to form a dative bind / coordinate bind
Coordination number is the number of coordinate binds in thst complex metal ion
Monodentate vs bidenatet etc
If it can donate two lone pairs = bi
What are the 5 different monodenate ligands and more IMPORTANTLY which ones REDUCE THE CHARGE
Water , ammonia neutral
Cl- , OH-, CN-
Bide are ligands en and oxalate?
Charge for oxalate ion?
EN is 1 2 diamino ethane , so two amino groups
Oxalate ion is c=o and connected to an O- twice
COO-COO-
Oxalate ions reduce the charge by 2
Shapes of complex ions based on coordination number
When is it 6, when is it 4!!! (+ why)
1) 6 = octahedral (90°) , 4 could be tetrahedral (109.5°) or SQAURE PLANAR (90°)
The coordinate number will be 6 for a standard element as long as the ligand is NOT CHLORINE
- chlorine atoms are BIG, so when they are present, the coordination number is capped at 4
WHEN IS IT A SQAURE PLANAR (regardless of ligand) (3)
Describe square planar shape
This is because if the central metal ion is PALADIUM , PLATINUM OR GOLD , then it automatically becomes SQUARE PLANAR
2)
- Has 4 ligands , 2 wedge 2 not
- 90°
Again what 3 elements does square planar automatically come
Palladium platinum and gold
So basically 8 electrons in d sub shell
Cos trans isomerism in sqaure planar?
Two atoms must be the same. If these atoms next ti each other = cis 90°
If they are opposite each other = trans 180°
Cis trans in octahedral
How is cis and trans shown
In this case the rest of ligands might be the same but you want TWO STANDOUT SAME
Again if they are right next to each other = cis
IF DIRECTLY OPPOSITE THEN TRANS
Cis trans isomerism in octahedral but BIDENTATE?
If bidentate , it’s gonna be that there will be two bidentate ligands which take up 4 space and two normal
Look at two normal, again next to = cis, oppsote = trans
Optical isomerism only for OCTAHEDRAL
Why are they not the same if rotate
This is two non superimposable mirror images
So thing about it you can’t rotate because if you did the ones going into the page would be going out
Cis trans isomerism for DNA
CIA Platin helps treatment in cancer by binding to dna in turn our cells and thus preventing them from diving
But has unpleasant side effects
Still used tho
