HNH bond angle in H3NF3?
The Lewis structure suggests a tetrahedral geometry (angle 109.5) there are no lone pairs to squeeze the angle to 107 so I would go with the answer closest to 109.5.
Why is the bond angle in NH3 only 107 degrees when the bond angle for BF3 is 120 degrees?
The bond angle in molecules has to do with the hybridization of the central atom. In NH3, the molecule is sp3 hybridized. 1 s and 3 p atomic orbitlals combine to form 4 sp3 hybridized molecular orbitals. 3 of these are bonds to Hydrogen. The 4th is occupied by the lone pair of electrons on nitrogen. Normally, as in CH4, the bond angles would be 109.5 degrees, but due to the non-bonding lone pair on the nitrogen, which because it is non-bonding (to another atom), has a higher electron density and pushes the 3 bonding MO's (molecular orbitals) away from it, making the bond angles smaller (approx 107).In BF3, the boron is sp2 hybridized, and 1 s and 2 p atomic orbitals combine to form 3 sp2 hybridized molecular orbitals. remember that Boron only has 3 valence electrons. In sp2 hybridization, the bonds are as far apart from each other in a single plane as possible, this being 120 degrees from each other. Boron has an empty p orbital which is perpendicular to the plane that the florine atoms are in, and being empty, can act as a lewis acid (look up Lewis acids and bases).(I'm assuming that you are already familiar with valence bond and molecular orbital theory, both of which you would need to be familiar with in order to understand the answer).source :Yahoo answers
Why is the bond angle the NH4+ greater than NH3?
Look here’s an easy approach to compare bond angles:First look at the hybridisation of the central atom:1)in case hybridisation is different,order of bond angle is: sp>sp2>sp3>sp3d…2)In case hybridisation is same check number of lone pairs on each central atom:a)if both have 0 Lone Pairs then their Bond angle is sameb)in case of non zero lone pairs,the molecule having more lone pairs will have smaller bond angle(due to electron pair repulsions)c)in case of non zero,equal no of lone pairs:i)When central atom is different but side atoms are same,bond angle is inversely proportional to size of central atom.ii)When side atom is different but central atom is same,bond angle is directly proportional to size of side atom.(exception:In case of Fluorine as side atom,bond angle is the lowest).Here in this question,both Nh3 and Nh4+ are sp3 hybridised.Since Nh3 has 1 lone pair but nh4+ has none,bond angle of nh4+ is greater than that of nh3.(How to check no.of lone pairs?-subtract number of side atoms from the hybridisation steric number)Hybridisation steric numbers:sp:2sp2:3sp3:4sp3d:4 and so on.Hope it clears the confusion:). Refer this chart to learn the shapes corresponding to different steric numbers.
Why is the bond angle in NF3 less than that in NH3?
RepulsionElectronic repulsion for bonded electrons:- l.p.-l.p. > l.p-b.p >b.p-b.p.ok… so in NH3nitrogen is more electronegative than Hydrogen, it attracts shared pair of electron and electron density accumulates near N , to minimize repulsion between bond pairs, angle increasesfor NF3bond pairs are near fluorine, this would lead to more b.p. l.p. repulsion and to minimize it, bond angle decreases.This explanation fits in above case however more apt explanation is given by Bent’s rule(higher level).2. Bent’s Rule.Bent's rule - Wikipedia (also go through some good book)According to Bent,the rule is"s-character concentrates more in orbitals directed towards more electropositive atoms and more p character develops in orbitals directed towards more electronegative atoms.Hybridized atomic orbitals with higher p character will have a smaller angle between them.Although, NH3 and NF3 have same hybridisation but F is more electronegative than H, the amount of p character in the N-F bonds in NF3, will be higher than in N-H bonds in NH3. Hence, bond angle in NF3 is smaller.Image credits: google.Hope it helps.
Explain the bonding of H3N-BF3?
[Answer: Lewis structures for NH3 and BF3: H | :N--H | H .. :F: | B--F::: | :F: .. Like the question states, BF3 is already stable, BUT the Boron (B) from BF3 would want to satisfy its octet (that is, have 8 electrons around it --> it only has 6 right now)(B is currently only sp^2 hybridized). On the other hand, the nitrogen (N) on NH3 is would want an extra pair of electrons to remove the lone pair of electrons it currently has, thus stabilizing itself. Thus, the B from BF3 and N from NH3 join together to form a bond, thus creating the compound H3N-BF3. The NH3 was acting as the Lewis base and BF3 was the Lewis acid.]
Why can NH3 form bonds with BF3 even though they are both molecules in their own right?
NH3 has a nonbonding pair of electrons and BF3 has an empty orbital. This is a classic Lewis acid-base reaction. NH3 is the Lewis base (electron rich) and BF3 is the Lewis acid (electron deficient). H3N + BF3 ---> H3N–BF3
Shape and bond angle of Boron trifluoride?
Shape and bond angle of Boron trifluoride? BF3, why does BF2 have a different shape and bond angle to the ammonia NH3 molucule? draw a dot and cross diagram of BF3NH3..indicate the presence of the dative covalent bond.
I have read that in BF3.NH3, the boron atom is sp3 hybridized. How is this possible?
Lewis structures for NH3 and BF3: H | :N--H | H.. :F: | B--F::: | :F: ..Like the question states, BF3 is already stable, BUT the Boron (B) from BF3 would want to satisfy its octet (that is, have 8 electrons around it --> it only has 6 right now)(B is currently only sp^2 hybridized). On the other hand, the nitrogen (N) on NH3 is would want an extra pair of electrons to remove the lone pair of electrons it currently has, thus stabilizing itself. Thus, the B from BF3 and N from NH3 join together to form a bond, thus creating the compound H3N-BF3. The NH3 was acting as the Lewis base and BF3 was the Lewis acid. NOW THERE ARE FOUR BONDS AROUND BORON HENCE THE HYBRIDISATION IS sp3.
Shapes of elements after formation of adduct?
The adduct has the shape of ethane. That is, both N and B are now tetrahedral. So the bond angle at N goes from 107 to 109.5, and at B from 120 to 109.5 degrees.
Why is BF3 written in two ways?
These are two methods of describing the bonds, the first being the Resonance (chemistry) - Wikipedia structure and the second being the Lewis structure - Wikipedia.The resonance structure supposes that the BF bonds take it in turns to be double so that the average is somewhere between single and double. It is usual to show a charge distribution as well, as given here by Tem5psu:Here is a nice example for the NO3- ion by Lisa Staugard:As others have observed, boron is unusual in being stable with only 6 instead of 8 electrons.I would say that the Lewis structure should be symmetrical (trigonal), though it is often drawn this way for 2 reasons (1) ease of drawing (the most common) (2) when put against other structures such as the coordination compound with NH3 as explained by Olivia Newan.