The Structure of Water
Biology: IB Diploma Higher Level, topic 1.1.2
The Structure of Water
The structure of a water molecule helps us to understand hydrogen bonding and the function of water.
Contents of a water molecule
- Water molecules (H2O) are made from:
- One oxygen atom.
- Two hydrogen atoms.
Polarity
- Water is a polar molecule.
- The oxygen atoms in water are slightly negatively charged.
- The hydrogen atoms in water are slightly positively charged.
Hydrogen bonding
- When polar covalent bonds containing hydrogen form, the hydrogen in that bond has a slightly positive charge because hydrogen’s electron is pulled more strongly toward the other element and away from the hydrogen.
- Because the hydrogen is slightly positive, it will be attracted to neighboring negative charges.
- When this happens, a weak interaction occurs between the δ+of the hydrogen from one molecule and the δ– charge on the more electronegative atoms of another molecule.
Hydrogen bonding - importance
- The polarity of water molecules means that a hydrogen atom on one water molecule is attracted to the oxygen atom on another water molecule.
- This attraction is called hydrogen bonding.
- Hydrogen bonds provide many of the critical, life-sustaining properties of water,
- Hydrogen bonding also stabilizes the structures of proteins and DNA, the building block of cells.
Test yourself on The Structure of Water
What are the components of a water molecule?
What is the attraction between water molecules?
Which of the following statements about water are true?