WHY IS A WATER MOLECULE POLAR?

Bellwork

WATER

BioChemistry

Recap from Friday

Review Water serves important biological functions

because of it’s chemical structure Hydrogen and oxygen in water share electrons

in a covalent bondOxygen “pulls” on the electron bond more than the hydrogen does• Makes oxygen more electronegative

Results in a slightly negative oxygen atom and a slightly positive hydrogen

The polar nature of water molecules to be attracted to one another The negatively charged oxygen

is attracted to the positively charged hydrogen of another water molecule Known as a hydrogen bond

Can form, break, and reform easily Occurs more easily in hot

waterHydrogen bonding accounts

for the unique properties of water

Target #8- I can explain how a hydrogen bond forms

Background

Attractive forces between molecules of the same type are called cohesive forces.

Attractive forces between molecules of different types are called adhesive forces.

Target #9- I can explain how surface tension is produced by cohesion

Cohesion An attraction between

molecules of the same substance

Causes water molecules to be drawn together Produces surface

tensionExplains why some

insects and spiders can walk on the surface

Caused by the strength of molecules holding onto each other

Target #10- I can identify capillary action is occurring when provided an example

Adhesion An attraction between molecules of

different substances Causes water molecules to be

attracted to other types of molecules Ex: water poured into a graduated

cylinder dips in the middleWater molecules are more

attracted to the glass than each other

Causes capillary action Occurs when water rises through a

tube against gravityEx: water up the trunk of a tree

Target #11- I can define the high heat capacity of water

Heat Capacity It takes a large amount of heat energy to cause water

molecules to move faster, which raises the temperature of water Therefore, the amount of heat needed to raise water’s

temperature is very high

Target #12- I can state why water is considered a universal solvent

Universal solvent Water can dissolve other

substances easily This means that

wherever water goes, either through the ground or through our bodies, it takes along valuable chemicals, minerals, and nutrients.

What property of water allows for some insects and spiders to walk on

water?

A- univeral solventB- high heat capacityC- low density of ice

D-adhesionE- cohesion

Checking for understanding

Blood in the human body, which is made mostly of water, is pumped 5 litres per

minute. Half the time, it is travelling up to the heart. What property of water allows

blood to travel in this direction?

A- univeral solventB- high heat capacityC- low density of ice

D-adhesionE- cohesion

Checking for Understanding