T1- p Block LP3 Flashcards
(30 cards)
How are elements in group 13 called?
Triels
What is electron deficiency?
There are fewer electrons than the number of valence erbitals.
What is inner pair effect on +1 oxidation state in group 13?
+1 oxidation becomes more stable down the group.
What are the elements in group 13?
Boron, aluminium, gallium, indium, thallium.
What is general electron configuration for group 13?
ns2 np1
Why group 13 compounds are Lewis acids?
Because they are electron deficient they can accept electrons very easily.
Why EX3 formula copmounds are good catalysts?
They can form a dative bond with Lewis bases that can keep forming and breaking easily.
What is amphoteric compound?
It is a compound that is able to react as a both base and an acid.
Why diboron trioxide is added to glass?
to improve its thermal properties
What is common reducing agent containing boron?
Sodium borohydride, NaBH4
Describe structure of borax, also known as disodium tetraborate.
Crystals of borax contains dianions with a tetrameric structure of four units of boron hydroxide. Two of four boron units have trigonal planar geometry, while the other two have tetrahedral geometry.
What is the order of Lewis acid strengths of boron halides?
BI3> BBr3 > BCl3 > BF3
How BF3 participate in π bonding?
Electrons are donated from full p orbital of F into the vacant p orbital on B.
Why BI3 is a strongest lewis acid from boron halides?
Because bonds are getting longer and overlap between p orbitals getting less favourable as we move atoms apart.
Why non fluoride halides prefferes dimerisation to π- bonding?
Because of the poor overlap between halogen and group 13 elements due to large diffuse orbitals.
What is dimerisation?
The chemical reaction that joins two molecular subunits, resulting in the formation of a single dimer.
What is molecular formula when boron reacts with hydrogen to form boron hydride and why?
B2H6, forms electron deficient dimer because B cannot form π- bond with H as H has no lone pairs.
Why in this molecule B-H-B bond is 3 centre- 2 electron bond?
It is because we have two sp3 hybrid orbitals on each B and two 1s orbitals from two bridging hydrogen atoms. We get 12 valence electrons, 8 used is forming the four terminal B-H bonds and 4 electrons are left to form two B-H-B bonds. So 2 electrons are delocalised across each B-H-B bond.
What is stability trend of the group 13 hydrides?
Stability decreases going down the group.
How to make aluminium hydride?
By adding alcohol groups to aluminium
What PSEP stands for?
Polyhedral Skeletal Electron Pairs
What is Wade’s rule?
A system based on Mo therory foe predicting the structure of a boron hydride by working out the number of pairs or electrons for cluster bonding.
What are the steps to find boron hydrides structure?
- Each BH unit donates two electrons
- Each H atom donates one elctron
- Add in any overall charge on the molecule
- Add up the number of electrons
- Calculate verticles n-1
- Count up the number of B-H units
- Place any remaining H as bridging H’s around open face
Using Wade’s rules when structure is closed?
When number of BH units are equal to the number of vertices.
