On Molecular Geometry of Hydrazine and Electronegativity

In summary, The molecular shape of Hydrazine N2H4 is trigonal pyramidal due to the presence of 3 H atoms and one pair of lone electrons around N. This shape is caused by steric effects, not electronegativity, as the central atom is not well-defined in hydrazine. In comparison, H2O has a larger bond angle due to the more electronegative O atom. However, in the case of hydrazine, steric forces play a more significant role in determining its molecular shape.
  • #1
Kyoma
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0

Homework Statement



1. What is the molecular shape of Hydrazine N2H4 w.r.t. N atom?

2. H2S and H2O, which one has a larger bond angle?

2. The attempt at a solution

1. Trigonal Pyramidal is the answer given. But Hydrazine has 5 atoms around its central atom and I'm unable to fathom why is it in trigonal pyramidal.

2. H2O is the answer as O is more electronegative. But why is this the case? I've checked the internet and nothing tells me why an electronegative central atom could cause a larger bond angle.

Thank you for your time.
 
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  • #2
Hint: hydrazine doesn't have a central atom.

Are you sure oxygen electronegativity plays a role here? Explanations I remember called mostly for steric effects.
 
  • #3
Ah~ there are 3 H atoms and one pair of lone electrons around N.

Steric forces? The explanation given to me was electronegativity?
 
  • #4
Kyoma said:
Ah~ there are 3 H atoms and one pair of lone electrons around N.

Sounds like ammonia, not hydrazine.

Steric forces? The explanation given to me was electronegativity?

Can't help it.
 
  • #5




Thank you for your question. I understand your curiosity and desire for a deeper understanding of molecular geometry and electronegativity. Let me explain the reasoning behind the answers to your questions.

1. The molecular shape of hydrazine (N2H4) with respect to the N atom is indeed trigonal pyramidal. This is due to the presence of two lone pairs of electrons on the central N atom. These lone pairs repel the bonded pairs, causing the molecule to adopt a trigonal pyramidal shape. The five atoms around the central N atom are arranged in a trigonal bipyramidal geometry, with the two H atoms at the axial positions and the two N atoms and one H atom at the equatorial positions. This arrangement results in the trigonal pyramidal shape of the molecule.

2. H2O has a larger bond angle compared to H2S due to the difference in electronegativity between the central atom and the bonded atoms. Oxygen (O) is more electronegative than sulfur (S), meaning it has a greater ability to attract electrons towards itself. This causes the bonded electron pairs in H2O to be pulled closer to the O atom, resulting in a smaller bond angle. On the other hand, the lower electronegativity of S in H2S leads to a larger bond angle. This is because the bonded pairs are spread out more evenly between the two atoms, resulting in a larger angle between them.

I hope this explanation helps clarify your doubts. Remember, as a scientist, it is important to question and seek a deeper understanding of scientific concepts. Keep up the curious mindset!
 

1. What is the molecular geometry of hydrazine?

The molecular geometry of hydrazine is bent or V-shaped, with a bond angle of approximately 109.5 degrees. This shape is due to the two lone pairs of electrons on the central nitrogen atom, which repel the bonding pairs and cause them to be slightly closer together than in a linear shape.

2. How does electronegativity affect the properties of hydrazine?

Electronegativity is a measure of an atom's ability to attract electrons in a chemical bond. In hydrazine, the two nitrogen atoms have similar electronegativities, resulting in a fairly symmetrical distribution of charge throughout the molecule. This makes hydrazine a polar molecule, with a slight negative charge on the nitrogen atoms and a slight positive charge on the hydrogens. This affects its reactivity and solubility in different solvents.

3. What is the molecular formula of hydrazine?

The molecular formula of hydrazine is N2H4. This means that it contains two nitrogen atoms and four hydrogen atoms.

4. How is the molecular geometry of hydrazine determined?

The molecular geometry of hydrazine is determined by the arrangement of its atoms and lone pairs of electrons around the central nitrogen atom. This can be determined using VSEPR theory, which predicts the shape of a molecule based on the number of bonding and lone pairs of electrons.

5. What are the uses of hydrazine in industry and research?

Hydrazine has several important industrial and research uses. It is commonly used as a rocket propellant due to its high energy density and low freezing point. It is also used as a reducing agent in various chemical reactions and as a precursor to other chemicals, such as pesticides and pharmaceuticals. In research, hydrazine is used as a reagent in organic synthesis and as a standard for measuring electronegativity values.

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