3.4 Chemistry of the d-block transition metals Flashcards
What elements on the periodic table does d-block cover?
What is a transition metal?
a metal that possesses a partially filled d sub shell in its atom or stable ions, this includes all the elements from scandium to nickel. Copper does have a full set of d orbitals as a metal but is considered to be a transition metal as it does have partially filled d-orbitals in most of its compounds.
What are the exceptions to electron configuration rules?
Chromium that fills half of its 3d orbital before going to the 4s orbital.
Copper completely fills its 3d before going to the 4s orbital.
In ions, for example a positive charged ion, what orbital are the electrons first removed from?
The 4s orbital. Because they are both close in energy levels so easier to loose from 4s than 3d.
what are the complete order of orbitals in electrons configuration?
1s, 2s, 2p, 3s, 3p, 3d, 4s, 4p
What is the common oxidation state of Cr?
+3
+6
What is the common oxidation state of Mn?
+2
+3
+4
+6
What is the common oxidation state of Fe?
+2
+3
What is the common oxidation state of Co?
+2
+3
What is the common oxidation state of Cu?
+1
+2
What bonds do transition metals usually form and how?
Co-ordinate bonds, due to transition metal ions usually being small and can have large positive charges they attract electron rich molecules (-) that have lone pairs, so these can form coordinate bonds with the empty orbitals on the transition metal ions.
What is a ligand? and what is it called when it combines with a transition metal?
A ligand is a small molecule with a lone pair that can form a bond to a transition metal, e.g H20,NH3,Cl-,CN-.
a complex
What are the two ways ligands position themselves around transition metals?
Usually 6 ligands are positiones octahedrally around the metal ion.
Sometimes 4 ligands are positioned tetrahedrally around the metal ions.
How do you draw the octahedral metal and ligand complex?
How do you draw tetrahedral complexes?
Give examples of complexes containing Fe2+ and Fe3+ and give their colour:
Give an example of a complex containing Cu2+ and give its colour:
Give an example of a complex containing Cr3+ and its colour :
Give an example of a complex with Co2+ in it and its colour:
What colour does [CuCl4]2- form?
A yellow or green complex
What colour does [CoCl4]2- form?
A blue complex
What are typical transition metal complexes of copper?
[Cu(H2O)6]2+, [Cu(NH3)4(H2O)2]2+, [CuCl4]2-
These complexes demonstrate the variation in transition metal complexes due to different ligands.
What are the typical transition metal complexes of cobalt?
[Co(H2O)6]2+, [CoCl4]2-
These complexes contain Co2+ ions and exhibit distinct properties.
What is the coordination geometry of the complexes [Cu(H2O)6]2+ and [Co(H2O)6]2+?
Octahedral
Each water molecule donates a lone pair to bond with the metal ion.
What colors are associated with aqueous solutions of Cu2+ and Co2+?
Cu2+ - pale blue; Co2+ - pink
These colors are characteristic of copper(II) and cobalt(II) compounds.
What happens when ammonia is added to a solution of [Cu(H2O)6]2+?
Forms [Cu(NH3)4(H2O)2]2+
The solution turns royal blue as four ammonia molecules replace water molecules.
What are the two isomeric forms of [Cu(NH3)4(H2O)2]2+?
Cis isomer, Trans isomer
The cis isomer has two water molecules next to each other, while the trans has them opposite.
What is the coordination geometry of the tetrahedral complexes formed by copper(II) or cobalt(II) ions with chloride ions?
Tetrahedral
The angles between the chlorides are approximately 109.5°.
What color change occurs for copper(II) when ligands change from water to chloride ions?
Pale blue to yellow/green
This color change is due to the change in ligands and coordination geometry.
What color change occurs for cobalt(II) when ligands change from water to chloride ions?
Pink to blue
This change is also due to the ligand and coordination geometry transition.
What type of acid reacts with copper(II) or cobalt(II) ions to form tetrahedral complexes?
Concentrated hydrochloric acid
This acid displaces the water molecules in the complexes.
List the colors of the oxoanions discussed.
- MnO4 - dark purple
- Cr2O7^2- - orange
- CrO4^2- - yellow
These colors are important for identifying different oxoanions.
