2 interactive concept widgets for Hydrogen. Drag any slider, change any number, and watch the formula and the answer update live. Built so you understand how each NEET problem actually works, not just the final number.
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Compare boiling points of Group 16 and Group 17 hydrides. See the anomalous jump at H₂O and HF explained by hydrogen bonding strength.
Compare boiling points of Group 16 and Group 17 hydrides. See why H₂O and HF have anomalously high BPs due to hydrogen bonding.
Hydrogen bonding occurs when H is bonded to a highly electronegative atom (F, O, N). It causes anomalously high boiling points.
Boiling points (Group 16 hydrides)
H₂Te
-2°C
H₂Se
-41°C
H₂S
-60°C
H₂O
+100°C
H-bond
Bar extends left for negative BP, right for positive. Zero line is in the middle.
Why H₂O and HF have anomalously high BPs
In Group 16, the expected trend from van der Waals forces would be BP increasing with molecular mass: H₂S < H₂Se < H₂Te. H₂O should have the lowest BP in the group — but it has +100°C, the highest! This is due to extensive hydrogen bonding: O has high electronegativity (3.44) and two lone pairs, so each H₂O forms up to 4 hydrogen bonds in liquid water, creating a strongly associated structure.
Same anomaly occurs with HF in Group 17 (F is the most electronegative element, 3.98). NH₃ also shows this anomaly in Group 15.
Hydrogen bonding conditions
1. H must be bonded to a highly electronegative atom: F, O, or N only.
2. The electronegative atom (donor) must have lone pairs to accept.
3. The bond is X-H...Y where X = F, O, N (donor); Y = F, O, N (acceptor).
Intermolecular H-bond: between two different molecules (water, HF, NH₃).
Intramolecular H-bond: within the same molecule (o-nitrophenol). Makes MP/BP lower than intermolecular.
Try this
Classify 15 hydrides as ionic, covalent, or metallic. See the reasoning for each and understand the trend across periods and groups.
Classify 15 hydrides as ionic, covalent, or metallic. Reasoning with group rules revealed after each answer.
Classify each hydride as ionic, covalent, or metallic. Reasoning is shown after your answer.
Ionic
Group 1 and 2 metals (s-block). H is H⁻ (hydride ion). React with water to give H₂. Conduct when molten.
Covalent
p-block elements. Shared electron pair bonds. Mostly gases or volatile liquids. Some are acidic (HCl), basic (NH₃), or neutral (CH₄).
Metallic / Interstitial
d-block transition metals. H fills interstices in metal lattice. Non-stoichiometric. Conduct electricity. Used for H₂ storage.
NaH
Sodium hydride
MgH₂
Magnesium hydride
CaH₂
Calcium hydride
AlH₃
Aluminium hydride
SiH₄
Silane
CH₄
Methane
NH₃
Ammonia
H₂O
Water
HF
Hydrogen fluoride
PdH₀.₆
Palladium hydride
TiH₂
Titanium hydride
LiAlH₄
Lithium aluminium hydride
B₂H₆
Diborane
GeH₄
Germane
SnH₄
Stannane
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