Chapter 24 - Transition elements Flashcards
what qualifies a transition metals?
d-block elements that form ions with an incomplete sub-shell
what are the physical properties of transition metals?
good conductor of electricity and heat, high density, shiny malleable, ductile, giant metallic lattice with metallic bonding and and high melting point and boiling point
why do transition metals form coloured compounds?
due to partially filled d sub-shells
why are transition metals often used as catalysts?
due to their ability to form multiple oxidation states
give two examples of a reaction with transition metal catalysts
haber process with a iron catalyst
hydrogenation of vegetable fats with a nickel catalyst
when is a complex ion formed?
when one or more molecules, or negative ions bond to a central metal ion
what is a ligand?
a molecule or ion that donates a pair of electrons to a central metal atom to form a coordinate bond
what is the coordination number?
the number of bonds
what shape and bond angle do complex ions with 6 coordinate bonds form?
octahedral, 90 degrees
what is a monodentate ligand?
a ligand that donates one pair of electrons to the central atom or ion
what is a bidentate ligand?
a ligand that donates two pair ls of electrons on two different atoms
in a monodentate ligand with two H2O molecules, where would they be positioned in the trans isomer?
opposite each other
in a monodentate ligand with two H2O molecules, where would they be positioned in the cis isomer?
next to each other
what is a ligand substitution reaction?
where one ligand in a complex ion is replaced by another ligand
what is the colour of copper sulfate dissolved in water?
pale blue
when the complex ion [Cu(H2O)6] reactions with ammonia, what complex ion is formed and what is the colour?
[Cu(NH3)4(H2O)2] 2+
dark blue
what are the two steps that take place in the reaction between [Cu(H2O6] and ammonia?
a pale blue precipitate of Cu(OH)2 is formed
this then dissolves in excess ammonia
what is the colour change when [Cu(H2O6] reactions with Cl and what complex ion is formed?
pale blue to yellow
[CuCl4] 2-
what happens if water is added to [CuCl4]?
a dilute, paler blue solution will form
what colour is [Cr(H2O6] 3+ ?
pale purple/violet
what is the colour change when [Cr(H2O6] 3+ reactions with ammonia?
violet to purple
what are the two steps in the reaction between [Cr(H2O6] 3+ and ammonia?
a grey/green precipitate of Cr(OH)3 is formed
this then dissolves in excess ammonia
how does ligand substitution affect haemoglobin?
carbon monoxide can displace oxygen in a ligand substitution reaction because it binds more strongly
when do precipitation reactions occur?
when two aqueous solutions containing ions react together to form an insoluble ionic solid
