Water Flashcards
How is a H20 molecule formed?
An oxygen atom requires two electrons to become stable.
It forms a covalent bond with two hydrogen atoms.
The electrons are pulled inwards, leaving the hydrogen nucleus slightly exposed
Why is water a dipole molecule?
due to the uneven distribution of electrons orbiting the atoms, the oxygen atom has a slight negative charge and the hydrogen atoms have a slight positive charge
due to the uneven distribution of charges, the water molecule is called a dipole
Are water molecules attracted to each other?
Yes, and they join by forming weak hydrogen bonds
Water has a latent heat of vaporisation. What does this mean?
Heat is lost from a surface when the water evaporates from it. It acts to cool the body during sweating
Water has a very high specific heat capacity. What does this mean?
A specific heat capacity is how much energy is required to make the temperature rise by 1 degree celsius.
Water has a high SHC because it provides a thermostable environment which is important for aquatic organisms eg fish
Water is a metabolite, why is this important?
It is a reactant in many important reactions eg photosynthesis and hydrolysis
Water molecules are polar. What does this mean?
They form hydrogen bonds which enables water to travel up xylem vessels in plants. It also produces surface tension which provides habitat for small organisms
Why does ice float?
Because it is less dense than water
Why is it beneficial that water is denser than air?
It can support large aquatic organisms such as whales, who collapse under their own weight when on land
Why is it important that water is transparent?
Light can pass through it so underwater plants can photosynthesise
Water has a low viscosity. Why is this important?
Water molecules can slide easily past one another and can act as a lubricant - eg mucus in the digestive system
