Why is the Shape of Hydrogen Selenide (H2Se) Bent?

  • Thread starter Thread starter coconut62
  • Start date Start date
  • Tags Tags
    Hydrogen Shape
AI Thread Summary
H2Se has a bent molecular shape due to the arrangement of its valence electrons. It contains six valence electrons, with two used for bonding with hydrogen atoms and four remaining as two lone pairs. The repulsive forces between these lone pairs are stronger than those between the bonding pairs, causing the bonding pairs to be pushed closer together. This results in a bond angle less than 180°, contrary to what might be expected if only considering the lone pairs' arrangement. The molecular geometry resembles that of water (H2O), where the presence of lone pairs alters the bond angles, leading to a bent shape rather than a linear one. The discussion emphasizes the importance of considering the three-dimensional arrangement of electron pairs to understand the molecular geometry accurately.
coconut62
Messages
161
Reaction score
1
Why does H2Se have a bent shape?

It has 6 valence electrons. 2 are used to bond with each of the hydrogens. 2 more up and 2 more down. So the repulsion of the lone pairs cancel off each other. Isn't this arrangement going to make the bond angle 180°?
 
Chemistry news on Phys.org
coconut62 said:
Why does H2Se have a bent shape?

It has 6 valence electrons. 2 are used to bond with each of the hydrogens. 2 more up and 2 more down. So the repulsion of the lone pairs cancel off each other. Isn't this arrangement going to make the bond angle 180°?

The repulsive forces between the lone pairs is greater than the forces between the 2 bonding pairs so the bonding pairs get pushed closer to increase the distance between the 2 lone pairs.

Another way to look at it is that molecules with 4 pairs of electrons form a tetrahedral shape, think methane, except in molecules like H2O or H2Se, 2 of the corners do not have another atom but they do have an electron pair.
 
trollcast said:
The repulsive forces between the lone pairs is greater than the forces between the 2 bonding pairs so the bonding pairs get pushed closer to increase the distance between the 2 lone pairs..

Push closer to where? If the two lone pairs are arranged at 180° to each other and so does the bond pairs, then maximum distance will be achieved, no?
 
coconut62 said:
Push closer to where? If the two lone pairs are arranged at 180° to each other and so does the bond pairs, then maximum distance will be achieved, no?

http://www.elmhurst.edu/~chm/vchembook/images/206water.gif

Try looking at that and see how the arrangement of the bonds and electron pairs maximises the distances between them (I think you are maybe only thinking about moving them round in the same plane)

I know the diagram says water but H2Se has the same electron geometry just the angles and lengths are a bit different.

Ps. The perspective of that diagram isn't great since it appears the lone pairs are closer together than the bonding pairs but in reality the bonding pairs should be closer but it should show the sort of 3d arrangement of the pairs around the central atom.
 
Last edited by a moderator:

Thread 'Humidity of a saturated NaCl solution with anticaking additive'

I want to test a humidity sensor with one or more saturated salt solutions. The table salt that I have on hand contains one of two anticaking agents, calcium silicate or sodium aluminosilicate. Will the presence of either of these additives (or iodine for that matter) significantly affect the equilibrium humidity? I searched and all the how-to-do-it guides did not address this question. One research paper I found reported that at 1.5% w/w calcium silicate increased the deliquescent point by...
View full post »

Thread 'Why does having 8 valence electrons make an element inert?'

I was introduced to the Octet Rule recently and make me wonder, why does 8 valence electrons or a full p orbital always make an element inert? What is so special with a full p orbital? Like take Calcium for an example, its outer orbital is filled but its only the s orbital thats filled so its still reactive not so much as the Alkaline metals but still pretty reactive. Can someone explain it to me? Thanks!!
View full post »

Thread 'Resists for etching Aluminium with NaOH'

I'm trying to find a cheap DIY method to etch holes of various shapes through 0.3mm Aluminium sheet using 5-10% Sodium Hydroxide. The idea is to apply a resist to the Aluminium then selectively ablate it off using a diode laser cutter and then dissolve away the Aluminium using Sodium Hydroxide. By cheap I mean resists costing say £20 in small quantities. The Internet has suggested various resists to try including... Enamel paint (only survived seconds in the NaOH!) Acrylic paint (only...
View full post »

Similar threads

Rationale for 6n+2 rule for the number of pi bonds in a non-cyclic molecule
Replies
3
Views
1K
Why are metals in aqueous solution basic, and non-metals acidic?
Replies
1
Views
2K
Group I/II Metal oxides always basic in aqueous solution -- why?
Replies
3
Views
2K
Why Isn't XeF4 Sea-Saw Shaped?
Replies
4
Views
6K
Bond angle of Hydrogen Sulphide
Replies
1
Views
7K
Why would a carbanion have a tetrahedral shape?
Replies
4
Views
4K
Why is the fluorine atom a poor hydrogen bond acceptor?
Replies
5
Views
4K
Why isn't the ion NH4+ capable of hydrogen bonding?
Replies
11
Views
11K
Memorizing VSEPR Structures: A Simple Method for Success
Replies
3
Views
43K
Is Dragos rule evidence of hybridization theory's failure?
Replies
9
Views
3K

Hot Threads

Recent Insights

Back
Top