Hydrogen bonding Flashcards Preview

CHEM - 2.2.2 Shape of Molecules and Intermolecular Forces > Hydrogen bonding > Flashcards

Flashcards in Hydrogen bonding Deck (4)
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1

What are Hydrogen bonds?

- 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

2

Why is water perfect for hydrogen bonding?

- 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

3

Why is the ice less dense than water?

- 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.

4

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

- Hydrogen bonds are extra forces
- More energy is needed to break hydrogen bonds in water