unshared electrons give oxygen atom a slight negative charge and each hydrogen atom a slightly positive charge.
makes water a POLAR MOLECULE
negatively charged oxygen atoms of 1 water molecule attracts positively charged hydrogen atom of another water molecule
this attraction is called HYDROGEN BONDING.
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PROPERTIES OF WATER caused by hydrogen bonding
HIGH SPECIFIC HEAT CAPACITY- amount of energy needed to raise the temperature of a 1kg substance by 1degree celsius.
hydrogen bonds can absorb a lot of energy so a lot of energy is needed to heat it up.
useful for organisms- it stops the rapid temperature change and keeps body temp fairly stable even as external environment heats up.
HIGH LATENT HEAT OF EVAPORATION-amount of energy absorbed by a substance without raising its temp as it changes from one state to another.
a lot of energy is needed to break hydrogen bonds between water molecules.
useful- helps in cooling when we sweat(water in sweat absorbs heat from body as it evaporates). also cools plant leaves in hot climates as water evaporates from mesophyll cells.
POLARITY makes water very COHESIVE(attraction between molecules of same type).
useful- helps water to flow in mass,great for transporting substances.
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PROPERTIES OF WATER
polarity makes it a good solvent for polar substances.
negative oxygen attracted to postive molecule and positive hydrogens attracted to negative molecule.
causes substances to dissolve- separation and dispersal of molecules or ions of a substance between the molecules of the solvent.
SURFACE TENSION-uppermost water molecules are pulled downwards.pulling forces draw them closer together. this forms strong layer on surface of the water.
small animals are able to walk on it without difficulty.
water is relatively dense(1.0g/cm3)-caused by molecules being pulled closely together by hydrogen bonds.
water is fairly viscous
Aquatic animals are streamlined,have cartilagous bones and air bladders to help them cut through water molecules more easily.
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