Hydrogen bonding Flashcards

1
Q

What are Hydrogen bonds?

A
  • Special type of permanent dipole-dipole interaction found between molecules containing a strongly electronegative atom with lone pairs (like oxygen, fluorine and nitrogen) and hydrogen atoms
  • Hydrogen bond acts between a lone pair on a EN atom in one molecule and a hydrogen atom in a different molecule
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2
Q

Why is water perfect for hydrogen bonding?

A
  • Unlike others it has 2 lone pairs AND two hydrogens so it is not limited by anything.
  • Due to H.Bonding water has anomalous properties
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3
Q

Why is the ice less dense than water?

A
  • Hydrogen bonds hold water molecules apart in an open lattice structure
  • The water molecules in ice are further apart than in water. This is because water can form 4 hydrogen bonds and when all are formed, it makes the bond extend outwards which holds water molecules slightly apart as a tetrahedral lattice full of holes.
  • Solid ice is less dense than liquid water and it floats. The holes in the open lattice structure collapses and molecules move closer making water more dense.
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4
Q

Why does water have a relatively high melting and boiling point?

A
  • Hydrogen bonds are extra forces

- More energy is needed to break hydrogen bonds in water

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