what is the bond order for BeF2? according to the lewis structure?
....according to MO diagrams its 0.
16 valence e-
To determine the bond order for BeF2 using the Lewis structure, we need to first write the Lewis structure for the molecule.
Step 1: Calculate the total number of valence electrons.
Be: Group 2 element, so it contributes 2 valence electrons.
F: Group 17 element, so each F contributes 7 valence electrons.
Total valence electrons = 2 (Be) + 2 (F) = 4 + 14 = 18 valence electrons.
Step 2: Determine the central atom and connect the other atoms to it with single bonds.
Since Be is less electronegative than F, Be should be the central atom. Connect both F atoms to Be with single bonds.
Step 3: Distribute the remaining valence electrons around the atoms to satisfy the octet rule.
Place the remaining 16 valence electrons around the F atoms as lone pairs.
Be: 2 valence electrons (0 lone pairs)
F: 8 valence electrons (4 lone pairs)
Step 4: Check if all atoms have achieved an octet.
Be: 2 valence electrons (satisfied)
F: 8 valence electrons (satisfied)
The Lewis structure for BeF2 looks like this:
Be:F:F
Step 5: Calculate the bond order.
Bond order is the number of bonds between a pair of atoms in a molecule. It is calculated as the number of bonding electrons divided by 2.
In the Lewis structure of BeF2, both Be-F bonds are formed by sharing two electrons each. Therefore, the bond order is:
Bond order = (Number of bonding electrons) / 2
= (2) / 2
= 1
So, according to the Lewis structure, the bond order for BeF2 is 1.
However, as you mentioned, according to molecular orbital (MO) diagrams, the bond order for BeF2 is 0. In MO theory, the molecular orbitals formed by the overlapping of atomic orbitals are filled with electrons. In the case of BeF2, the molecular orbital diagram shows that the electrons are filled in the anti-bonding molecular orbitals, canceling out the bonding and resulting in a bond order of 0.
Please note that the Lewis structure provides an approximate representation of bonding while MO theory provides a more detailed understanding. Both approaches have their uses depending on the context and level of detail needed.