Water And Life

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polar covalent bond

Back 1

In a polar covalent bond, the electrons shared by the atoms spend a greater amount of time, on the average, closer to the Oxygen (-) nucleus than the Hydrogen (+) nucleus.

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polar molecule

Back 2

unequal sharing of electrons and water's V like shape make it a polar molecule, meaning that is overall charge is unevenly distributed, bonds arrange asymmetrically

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cohesion

Back 3

is the property of water that makes it's molecules attract to one and another, hold the substances together

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adhesion

Back 4

the clinging of one substance to another

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surface tension

Back 5

measure of how difficult it is to break or stretch the surface of a liquid

The molecules at the surface do not have other like molecules on all sides of them and consequently they cohere more strongly to those directly associated with them on the surface. This forms a surface "film" which makes it more difficult to move an object through the surface than to move it when it is completely submersed.

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kinetic energy

Back 6

the energy of movement, anything that moves has it, molecules are always moving the faster they move the greater the kinetic energy

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heat

Back 7

a form of energy, for a given body of matter the amount of heat is the measure of the total kinetic energy due to the motion of molecules. thus heat depends in part of the matter's volume

water in coffee pot -high temp. - lower heat

water in a pool- low temp. - high heat

pool has greater volume

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temperature

Back 8

is a measure of heat intensity that represents the average kinetic energy of the molecules, regardless of the volume

water in coffee pot -high temp. - lower heat

water in a pool- low temp. - high heat

pool has greater volume

Front 9

Calorie (cal)

Back 9

unit of heat, amount of heat it takes to raise 1g of water 1 degree C, or the amount it releases to cool 1C

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kilocalorie (kcal)

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1000 cal is the quantity of heat required to raise the temp. of one kilogram of water by 1C

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joule (j)

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.239 cal, one cal.=4.184 J

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specific heat

Back 12

the amount of heat that must be absorbed or lost for 1g of that substance to change in temp. by 1C

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heat of vaporization

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is the quantity of heat a liquid must absorb for 1g of it to be converted from the liquid to the gas state

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evaporative cooling

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as the liquid evaporates the surface cools down, the "hottest molecules" the ones with the greatest kinetic energy are the most likely to leave as gas

help prevent over heating (ex. water, person)

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heat of vaporization

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is the quantity of heat a liquid must absorb for 1g of it to be converted from the liquid to the gaseous state

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evapoartive cooling

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occurs b/c the "hottest" molecules, those with the greatest kinetic energy, are the most likely to leave as gas. (ie. as a liquid evapoates the surface of the liquid begins to cool down)

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solution

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a liquid that is a completly homogeneous mixture of two or more substances

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solvent

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he dissolving agent of a solution (ie. H2O)

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solute

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the substance that is dissolved in a solution (ie. salt)

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hydration shell

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the sphere of water molecules around each dissolved ion (ie. H2O surrounds sodium and chloride ions seperating them from each other)

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hydrophilic

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any substance that has a affinity for water

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colloid

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a stable suspension of fine particles in a liquid. molecules are to large to dissolve, but still hydrophilic

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hydophobic

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substances that do not have a affinity for water. that nonionic and nonpolar (or otherwise can not form hydrogen bonds) atually seem to repel water

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molecular mass

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the sum of the masses of all the atoms in a molecule

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mole (mol)

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represents an exact # of objects: 6.02X10^23 (Avogadro's number) which = 1g

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molarity

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the number of moles of solute per liter of solution is the unity of concentration most often used by biologist for aqueous solutions

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hydrogen ion H+

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strictly, the nucleus of a hydrogen atom separated from its accompanying electron. The hydrogen nucleus is made up of a particle carrying a unit positive electric charge, called a proton.

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hydroxide ion OH-

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is a diatomic anion with chemical formula OH−. It consists of an oxygen and hydrogen atom held together by a covalent bond, and carries a negative electric charge. It is an important but usually minor constituent of water.

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acid

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is a subastance that increases the hydrogen ion concentration of a solution

(ex. HCL -> H+ + Cl- hydrogen ion dissociate from Chloride ion when HCL is added to H2O)

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base

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a substance that reduces the hydrogen ion concentration concentration in a solution (ex. NH3 + H+ <--> NH4 (valence shell attraction)

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buffer

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is a substance that minizes changes in the concentration of H+ and OH- in a solution. It does so by excepting H+ ions from a sultions when they are in excess and donating H+ ions to the solution when they have been depleted.

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ocean acidification

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is the ongoing decrease in the pH of the Earth's oceans, caused by the uptake of carbon dioxide (CO2) from the atmosphere. An estimated 30–40% of the carbon dioxide from human activity released into the atmosphere dissolves into oceans, rivers and lakes.

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acid precipitation

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rain, snow, or fog with a pH lower than 5.2. damage life in lakes, streams and effects plants by changing soil chemistry, possesses high levels of H+ ions