transition metals Flashcards
What are the d-block transition metals?
metals with an incomplete d subshell in at least one of their ions
How are d orbitals filled? + exceptions
follows the aufbau principle
exceptions: chromium and copper atoms
These exceptions are due to the special stability associated with the d subshell being half-filled or completely filled
What happens when atoms from the first row of transition elements form ions?
It is the 4s electrons that are lost first rather than the 3d electrons
When is an element said to be in a particular oxidation state?
When it has a specific oxidation number
How are oxidation numbers determined? (rules)
-uncombined elements=0
-ions contraction single atoms=same as charge
-in most of its compounds, oxygen=-2
-in most of its compounds, hydrogen=+1
-the sum of all the oxidation numbers of all the atoms in a a neutral compound=0
-the sum of all the oxidation numbers in all of the atoms in a polyatomic ion=the charge on the ion
What is different about transition metal’s oxidation numbers?
They can have different oxidation states in compounds
What may be different about compounds of the same transition metal in different oxidation states?
colour
What can oxidation and reduction be defined as?
oxidation-increase in oxidation number
reduction-decrease in oxidation number
What can changes in oxidation number of transition metal ions be used to determine?
whether oxidation or reduction has occurred
How can we tell between oxidising and reducing agents?
compounds containing metals in high oxidation states are often oxidising agents
compounds with metals in low oxidation states are often reducing agents
What are ligands?
They may be negative ions or molecules with non-bonding pairs of electrons that they donate to the central atom or ion, forming dative covalent bonds
A ligand is a molecule, ion or atom which contains at least 1 lone pair of electrons
What can ligands be classified as?
monodentate (dontate 1 pair e-), bidentate (2 pairs->must be on different parts of molecule/not the same atom), up to hexagonal
(it is possible to deduce the ligand classification from a formula or structure of the ligand or complex)
What is the coordination number?
The total number of bonds from the ligands to the central transition metal (determines shape)
How can you identify a transition metal?
1-They can produce ions with different valencies
2-They produce coloured compounds
3-They can act as catylists
What metals are not considered transition metals and why?
Scandium and zinc
The definition for a transition metal states that they can form at least 1 ion with an incomplete d shell
zinc is full
