24 Transition Elements Flashcards
Where are the d-block elements located on the periodic table? (1 mark)
In the middle
In groups 3-12
Give 3 properties of d-block elements. (3 marks)
Metallic
High melting and boiling points
Conduct electricity and heat
Shiny in appearance
What makes a d-block element a d-block element? (1 mark)
A d sub-shell is being filled (4s fills before 3d)
What are the two exceptions to the following rule:
‘the 4s shell fills before the 3d shell’. (2 marks)
Chromium
Copper
Why are chromium and copper’s 4 sub-shells not full? ( 2 marks)
The d5 and d10 subshells provide additional stability to the atoms.
What is a transition element? (1 mark)
A d-block element that can form at least one ion with a partially filled d-orbital.
Not all d-block elements are transition metals, give two examples that fit this description. (2 marks)
Scandium
Zinc
Why is scandium not a transition metal? (2 marks)
Scandium only forms Sc3+ by loss of 2 4s and 1 3d electrons, the resulting ion has no electrons a d-orbital.
Why is zinc not a transition metal? (2 marks)
Zinc only forms Zn2+ by loss of 2 4s, the resulting ion has a full d-orbital.
Give three properties of transition elements. (3 marks)
Form coloured compounds
The elements and compounds can act as catalysts
They readily change oxidation states.
State the catalyst used in the Haber process. ( 1mark)
Iron
What is the catalyst used in the contact process? (1 mark)
Vandium oxide
What makes transition metals good catalysts? (1 mark)
They are good at adsorbing substances onto their surface.
What is a complex ion? (1 mark)
One or more molecules/ negatively charged ions bonded to a central metal ion.
What are the molecules/ negative ions bonded to the central metal ion called in a complex ion? (1 mark)
Ligands
Define the term ligand. (1 mark)
A molecule or ion that donates a pair of electrons t a central ion to form a dative covalent bond.
What is a dative covalent bond? (1 mark)
When one atom provides both of the electrons in a covalent bond.
What does the coordination number tell you about a complex ion? (1 mark)
The coordination number indicates the number of covalent bonds attached to the central metal ion.
What is a mondentate ligand? (1 mark)
A ligand that can donate one pair of electrons to a central metal ion.
What is a bidentate ligand? (1 mark)
A ligand that can donate two pairs of electrons to a central metal ion.
What is the shape and bond angle of 6-coordinate complexes? (1 mark)
Octahedral
90 degrees
What is the coordinate number of an octahedral complex? (1 mark)
6
What are the shape(s) and bond angle(s) of 4-coordinate complexes? (1 mark)
tetrahedral- 109.5 degrees
square planar- 90 degrees
What is the coordinate number of a tetrahedral complex? (1 mark)
4
In what elements do square planar shapes occur? (3 marks)
Gold (III)
Platinum (II)
Palladium (II)
What is the bond angle of a tetrahedral complex ion? (1 mark)
109.5 degrees
What is the bond angle of a square planar complex ion? (1 mark)
90 degrees
What types of stereoisomerism can be displayed in complex ions? (2 marks)
Cis-trans isomerism
Optical isomerism
In what type of complex ions does cis-trans isomerism occur? (2 marks)
Square planar
Octahedral
What makes a cis complex ion cis? ( 2 marks)
Identical groups are adjacent.
90 degrees between identical groups.
What makes a trans complex ion trans? ( 2 marks)
Identical groups are opposite.
180 degrees between identical groups.
What are optical isomers? (1 mark)
Non-superimposable mirror images of each other.
In what type of complex ions does optical isomerism occur? (2 marks)
Octahedral, containing two or more bidentate ligands.
How does cis-platin treat cancer? (2 marks)
By forming a platinum complex inside of a cell which binds to the DNA of cancer cells and prevents it from replicating.
What is ligand substitution? (1 mark)
When one ligand in a complex ion is replaced by another ligand.
What ion is formed when copper sulfate is dissolved in water? (1 mark)
[Cu(H2O)6]2+
What colour is the solution formed when copper sulfate is dissolved in water? (1 mark)
Pale blue
What happens when copper sulfate is dissolved in water and then reacted with excess ammonia? (3 marks)
The pale blue solution changes to a dark blue solution.
Four ammonia ligands replace four of the water ligands.
Two different reactions take place; first a precipitate forms (Cu(OH)2), it then dissolves in the excess ammonia.
What happens when copper sulfate is dissolved in water and then reacted with excess hydrochloric acid? (3 marks)
The pale blue solution changes to a yellow solution.
Four chloride ligands replace the six water ligands.
The solution changes to green before going to yellow, as the two colours mix.
What complex ion is formed when chromium (III) potassium surface is dissolved in water? (1 mark)
[Cr(H2O)6]3+
What complex ion is formed when chromium (III) sultans is dissolved in water? (1 mark)
[Cr(H2O)5SO4]+
What happens when chromium (III) potassium sulfate is dissolved in water and then reacted with excess ammonia? (4 marks)
[Cr(H2O)6]3+ is formed, then reacted with ammonia to form [Cr(OH)3] (a precipitate).
Changing colour from purple to grey-green.
This then dissolved in the excess ammonia to form [Cr(NH3)6]3+
Changing colour from grey-green to violet.
Why is it dangerous to inhale CO? (2 marks)
CO can also bind to the iron in haemoglobin, and binds more strongly than oxygen, the bond is irreversible, preventing transport of oxygen.
Is Cu(OH)2 soluble in excess ammonia? (1 mark)
No
Is Cr(OH)3 soluble in excess NaOH? (1 mark)
Yes
Is Fe(OH)2 soluble in excess ammonia? (1 mark)
No
Is Fe(OH)3 soluble in excess NaOH? (1 mark)
No
Is Mn(OH)2 soluble in excess NaOH? (1 mark)
Yes
What colour is MnO4-? (1 mark)
Purple
What colour is Cr2O72-? (1 mark)
Orange
What colour is Fe3+? (1 mark)
Orange-brown
What colour is I2? (1 mark)
Brown
What colour is Cr3+? (1 mark)
Green
Give an equation for the oxidation of Cr3+ to Cr2O42-. (3 marks)
3H2O2 + 2Cr3+ + 10OH- —> 2CrO42- + 8H2O
What colour is Cu2+? (1 mark)
Pale blue
Suggest why the entropy of water is zero at 0K. (1 mark)
There is no disorder.
Define entropy. (1 mark)
The level of disorder of a reaction.
