Water

Definition

Water is a simple molecule composed of two hydrogen atoms covalently bonded to one oxygen atom, forming the chemical formula H₂O. This unique structure gives water distinct properties, such as being a polar solvent and having high surface tension, which are critical for biochemical reactions and processes in living organisms.

5 Must Know Facts For Your Next Test

1. Water's molecular geometry is bent, with an angle of about 104.5 degrees between the hydrogen-oxygen-hydrogen atoms, which contributes to its polar nature.
2. The polarity of water molecules allows for hydrogen bonding, resulting in high boiling and melting points compared to other similar-sized molecules.
3. Water has a high specific heat capacity, meaning it can absorb and store large amounts of heat energy without significant changes in temperature, which is essential for regulating climate and biological processes.
4. Due to its polarity, water can dissolve a wide range of ionic and polar substances, making it crucial for chemical reactions within cells and the transport of nutrients and waste.
5. The unique property of water's surface tension allows small organisms to walk on its surface and is critical for processes like capillary action in plants.

Review Questions

• How does the molecular structure of water contribute to its properties as a solvent?
  • The molecular structure of water, with its bent shape and polar nature, allows it to interact effectively with various solutes. The partial positive charges on the hydrogen atoms can attract negatively charged ions or polar molecules, while the partial negative charge on the oxygen atom can attract positively charged ions. This interaction enables water to surround and dissolve ionic compounds and other polar substances, making it an excellent solvent in biological systems.
• Discuss the significance of hydrogen bonding in water regarding its physical properties.
  • Hydrogen bonding plays a vital role in determining water's physical properties. These bonds create strong interactions between water molecules, leading to higher boiling and melting points compared to other small molecules. The cohesive nature from hydrogen bonds results in high surface tension, while the ability to form multiple hydrogen bonds allows water to absorb heat effectively, influencing temperature regulation in both natural environments and biological organisms.
• Evaluate the role of water's high specific heat capacity in supporting life on Earth.
  • Water's high specific heat capacity is crucial for sustaining life on Earth as it helps stabilize temperatures in both environments and living organisms. This property allows large bodies of water to absorb significant amounts of heat during the day and release it at night, moderating climate fluctuations. In organisms, this means that internal temperatures can remain stable despite external changes, enabling biochemical processes to occur efficiently and maintaining homeostasis vital for life.

Related terms

polar molecule:

A molecule that has a partial positive charge on one side and a partial negative charge on the other, leading to an uneven distribution of electrical charge.

hydrogen bonding: The weak attractive force between a hydrogen atom, which is covalently bonded to a highly electronegative atom, and another electronegative atom, contributing to water's unique properties.

solvent: A substance that dissolves a solute, resulting in a solution; water is often referred to as the 'universal solvent' due to its ability to dissolve many substances.