Valnce Bond Theory+Hybridization Flashcards
Explain the diffrence between ionic and covalent bond
-covalent bonds have molecular geometry, ionic bonds have crystalline structures
-covalent bond is directional while in the ionic bond atom forms electrostatic bonds in all directions
-covalent bond is very strong and large energy is needd to break it
What are 2 theories of bonding that are more advanced than the Lewis model
1.Valenc bond approach-shared e- pairs form bonds between the atoms. A bond arises from the intersection between the atomic orbitals on two atoms to give a bonding orbital that is located between the 2 atoms(bonding orbital contains 2e-)
2.Molecular orbital approach-atomic orbitals combine to form a set of molecular orbitals that are spread out over the whole molecule. Orbitals-delocalized
According to valence bond theory, a covalent bond can be formed if?
- Atomicnorbital of one atom is superimposed by the atomicnorbital of the other atom
- The total number of e- in two superimposed orbitls can not be higher than 2
How many bonds can atom form
Same as number of unpaired e-
What is exception to the rule that atoms number of bonds equal to number of unpaired e-
Carbon- 2 unpaired e-;4bonds
Explain concept of hybridization
Atoms are able to change the shape and energies of their atomic orbitals so they can increase their opportunities to form bonds
Hybridization involves interaction between the orbitals of the same atom during the formstion of bonds with another atom
What is hybrid orbital
It is the result of the linear combination of atomic orbitals of the same atom. They all have the same energy
How does a hybrid orbital look
They have the node at the nucleus and contain 2 lobes of different size
What properties can empty orbital give
Gives atom an opportunity to form coordinative bond with another atom or molecule that has a lone pair of e-
What is hybridization when atom forms 5 covalent bonds
sp³d
What is sp³d² and give an example
When atom forms 6 covalent bonds, ex=sulfur
What is sigma bond(б)
Strongest type of covalent bond formed by head on overlapping of atomic orbitals because the extent of overlap is maximum
What is a п bond
Sideways or lateral overlapping of atomic orbital.
Is shape determined by sigma or pi bond
Sigma bonds
Is sigma or pi bond stronger
Sigma bond
What defined geometry of the molecule
Bond angle
What are assumtions of VSEPR theory
- The atoms in a molecule are held together by pairs of e- known as bonding pairs
- Some atoms may have pairs of e- that are not involved in bonding and they are called lone pairs
- On each atom e- pairs adopt a position as far away from one another as possible
How should double and triple.bonds be treated when deciding the geometry of the molecule
They should be treated as single bonds
Name all geometries
•Sp= No lone pairs, linear
•sp²= no lone pairs-trigonal planar; 1 lone pair=bent/angular
•sp³= 0 lone pairs= tetrahedral; 1 lone pair= trigonal pyramidial, 2 lome pairs=bent/angular
•sp³d=0 lons pairs=trignal bipyramidial, 1 lone pair= sawhorse/seesaw; 2 lone pairs= T shape, 3 lone pairs= linear
•sp³d²= 0 pone pairs=octahedral; 1 lone pair= square pyramidial; 2lone pairs= square planar, 3 pone pairs=T shape; 4 lone pairs=linear
Steps to determine molecular geometry from the VSEPR
- Draw Lewis structure to show covalent bonds and lone pairs and calculate formal charges
- Calculate number of e- pairs from the central atom(bonding and line pairs)
- From the number of bonding and line pairs determine the geometry
