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What is the structure of XeF4 and ICl4-?

square planar (90 degrees) because of 2 lone pairs on the central element 4 bonds square planar because of 3 lone pairs and one from the ion

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23 questions
What is the structure of XeF4 and ICl4-?
Square planar (90 degrees) because of 2 lone pairs on the central element 4 bonds square planar because of 3 lone pairs and one from the ion
What is the structure of ClF3?
T-shaped because of 2 lone pairs and 3 bonds
What is a sigma bond? (4)
Head on overlap of atomic orbitals so that the electron density is between the nuclei of the bonding atoms S-S P-P S-P
What is a pi bond? (7)
Sideways overlap of atomic orbitals so electron density is above and below the nuclei of the bonding atoms can only happen with p orbitals does not happen with single bonds only with double, triple there is always a sigma bond with a pi bond double bond = 1 pi bond triple bond = 2 pi bonds
What is formal charge?
Atomic charge of a molecule, if all the atoms had the same electronegativity used to determine which lewis structure is preferred by whichever is closest to 0
What is the formula for formal charge?
Number of total valence electrons - Number of non-bonding electrons - number of bonding electrons / 2
If both lewis structure's FC is 0? (2)
Whichever individual atoms are closest to 0 is preferred If the negative charge is on the more electronegative atom (F, O, N)
What are delocalized pi electrons?
Electrons that are shared between more than 2 nuclei = not fixed between a pair of atoms exist in all molecules or ions where there is more than one lewis structure possible (Resonance structures) represented by a dashed line
Why do electrons delocalize in resonance structures of a molecule?
Because the bond lengths and strengths are equal as there are equal contributions from both of the resonance structures makes a resonance hybrid (mixture of both the resonance forms)
What is delocalization?
Sharing of a pair of electrons bw 3 or more atoms
How do we know if something has delocalized pi electrons?
If more than one resonance structure is possible and the only difference is the position of a double bond
An example of a molecule with delocalised electrons? (7) Ben
Benzene C6H6 has 2 resonance structures where the double and single bonds are in different positions The bonds are intermediate = resonance hybrid structure Unhybridised P orbital == overlap to form a delocalised pi system shows with a dashed line 6 pi electrons - one form each unhybridised orbital circle shows delocalised pi electrons
What are resonance structures?
2 or more lewis structures to represent a molecule or ion that can't be described with just one lewis structure difference in position of double bonds
Give another example of delocalised electrons in a molecule (ethan)
Ethanoate ion CH3COO- difference between the two resoncance structures is a different position for the double bond between O-C
What is VSEPR theory?
Valence shell electron pair repulsion theory is used to predict the geometry of molecules electron pairs repel each other and spread as far apart as possible
What is electron domain?
Bonds / lone pairs of electrons around an atom in a molecule single doube and triple bonds all count as one electron domain
Which atoms can have expanded octets?
Atoms in period 3 and onwards such as (Cl, Br, S and P) can use their d orbitals in bonding
What is hybridisation?
It is the mixing of atomic orbitals to produce hybrid orbitals in bonding 3 types are = sp3, sp2, and sp
Describe sp3 hybridisation
Eg: carbon atom 2s2 and 2p2 an electron from the 2s sub level is promoted to an empty orbital in the 2p sub level = excited state (1 e in 2s and 3 in 2p) The 2s and 2p orbitals mix to form sp3 hybrid orbitals = degenerate same energy explains why carbon can form 4 bonds
Describe sp2 hybridisation
An electron is promoted to the 2p sub level = excited state mix to form 3 sp2 orbitals with one unhybridised p orbital unhybridised p orbital forms a pi bond (double bond)
Describe sp hybridisation
Electron is promoted = excited 1 2s and 1 2p orbital mixes to form sp while 2 unhybridised p orbitals remain 2 unhybridised orbitals form 2 pi bonds
Molecular geometry of sp, sp2 and sp3
Linear (2 domains) 180 degrees eg: co2 trigonal planar (3 domains)) 120 degrees BF3 Tetrahedral (4 domains) 109.5 H2O can be tetra, bent or trigonal pyramidal
What are free radicals?
Highly reactive atoms with unpaired electrons (an O2 atom with 2 unpaired electrons