KA4- Transition Metals Flashcards
What are transition metals
definition
A substance found in the d-block which has at least one ion with an incomplete d-subshell
What are metals but are excluded because of the definition used at AH?
Sc (scandium) and Zn (zinc) as Sc has no d subshell and Zn has a full subshell
What are the characteristics of transition metals?
- produce ions with different valencies
- produce a coloured compound
- act as a catalyst
When converting transiton metal atoms into their ions (drawing the box orbital notation) what is the rule to use?
always remove 4s electrons before the 3d electrons
oxidation states
transition metals exibit different oxidation states of varying ability because they cannot only use their 4s electrons but some or all of their 3d electrons
oxidation number
how many electrons have been lost
What are the rules for oxidation states?
- simple ions (na+, K+, Cl-) count as +1 or -1
- oxygen is always assumed to be -2
- hydrogen is lways assumed to be +1
- overall charge on a compound is always 0 (but the overall charge for ions)
- in polyatomic ions, the sum of all the oxidation numbers is eual to the overll charge on the ion
What is monodentate ligands?
give an example
- only form one daitive bond
- H2O, NH3, Cl-, CN-, OH-
What is a ligand?
Molecule or anion (more electron than proteins) which attach to the meta atom in a complex via diative covalent bonds
What is a bidentate ligand?
give an example
- can form 2 daitive bonds
- oxalato
What is a polydentate ligand?
- multiple donor sites
- EDTA, chlorophyll, Haemaglobin
Name the 5 rules for naming coordination compoounds?
- cation pecides naming anion
- complex ion names are one word
What are the rules concerning forming a complex?
- The cation or anion cannot exit on their own and must have their charge balanced
- the complex ion wil bond with oppositely charged ions to form a ccomplex
- cation is +ve
- anion is -ve
What is responsible for the characteristic colours seen in so many transition metal compounds?
the ligands surrounding the metal ions
How are the circumstances created that lead to the adsorption of some light from the visible spectrum?
interactions between the ligands and electrons
What does the binding of ligands to metal ions cause?
d->d transitions
causes orbitals to split (when ligands are involved)
Why are transition metals good exxamples of catalysts?
- due to the existence of partially filled d-orbitals with unpaired electrons
- ability to change oxidation states so easily
Heterogeneous & Homogeneous
definitions
- different state to reactants
- same state to reactants
How are there alternative reaction pathways with tranisiton metals acting as the catalysts that provide lower activation energy?
the presence of unpaired d-electrons or empty d-orbitals allow intermediate complexes to form
What is the coordination number?
How many bonds the metal makes
When asked the classification of a ligand, what does this mean?
How many bonds a ligand is making
If white light was shone on a copper colbalt complex what would it adsorb and then give off?
It would adsorb yellow light so therefore give off blue light
Why do d-orbitals split?
When a ligand comes into contact with a transition metal the d-orbitals split as the electrons are replused wanting to go to the next possible energy level (this is created by the splitting of the d-orbitals
How to transition metals absorb light?
lower energy d orbitals can absorb energy anf move to higher energy d orbitals
Concerning the colours we see in transition metals, why do we see these colours?
- where the ligand is on the spectrochemical series
- we will see the white light minus the colour adsorbed
