Water Flashcards
1
Q
What is a polar molecule
A
- regions of positivity and negativity
- occurs due to electrons not being shared equally by atoms- spend more time closer to one of the atoms in the bond
2
Q
Which molecule in water has a greater share of electrons
A
- Oxygen
- (hydrogen and oxygen ae examples of molecules that don’t share electrons equally, so water is polar)
3
Q
What are the bonds between water molecules, and why do they form
A
- (weak) hydrogen bonds
- the positive and negative regions of water molecules attract each other and bond
4
Q
Why has water got a very unusually high boiling point?
A
- very small and light molecule
- takes a lot of energy and therefore heat to increase temperature/ break bonds
5
Q
Structural features of ice (frozen water)
A
- LESS DENSE than water, due to hydrogen bonds
- as water is cooled, the H bonds fix the position of the polar water molecules, further apart than when it is a liquid, producing a giant rigid open structure
- each oxygen atom at the centre of a tetrahedral arrangement of hydrogen atoms
- floats as less dense
6
Q
What are cohesion and adhesion
A
- characteristics of water
- cohesion= water molecules are attracted to each other, water molecules are more strongly cohesive to each other than they are to air
- adhesion= water molecules are attracted to materials, forms droplets
7
Q
Why is water a good habitat
A
- stable
- doesn’t change temperature easily
- provides a constant environment
- ice can form an insulating layer, protecting organisms underneath from freezing
- water surface tension strong enough to support insects
8
Q
How and why is water a coolant?
A
- water helps buffer temperature changes in chemical reactions- lots of energy needed to break H bond
9
Q
How and why is water an efficient transport medium?
A
- cohesive properties mean the water molecules stick together when transported
- adhesion and cohesion result in water exhibiting capillary action (move up narrow tube against gravity)
- many substances soluble in water
10
Q
A
