Composition of WaterComposition of Water

•Two Hydrogen atoms and Two Hydrogen atoms and One Oxygen atomOne Oxygen atom

•The molecular formula for The molecular formula for water is Hwater is H22O.O.

Polarity –Polarity –

•The most important property of The most important property of water is that it is polar.water is that it is polar.

– A water molecule is polar because A water molecule is polar because there is an uneven distribution of there is an uneven distribution of electrons between the oxygen and electrons between the oxygen and hydrogen atoms. hydrogen atoms.

– The hydrogen end of the molecule is The hydrogen end of the molecule is slightly positive and the oxygen end slightly positive and the oxygen end is slightly negative.is slightly negative.

Bohr Model of WaterBohr Model of Water

•Water molecules can attract to Water molecules can attract to each other because of this polarity. each other because of this polarity.

•The attraction between the oxygen The attraction between the oxygen atom (slightly negative) on one atom (slightly negative) on one water molecule and the hydrogen water molecule and the hydrogen atom (slightly positive) on another atom (slightly positive) on another water molecule is an example of a water molecule is an example of a hydrogen bondhydrogen bond..

Hydrogen BondsHydrogen Bonds

• Water’s ability to form, Water’s ability to form, hydrogen bonds is hydrogen bonds is responsible for many of its responsible for many of its properties. Some of these properties. Some of these properties are:properties are:

– CohesionCohesion Surface TensionSurface Tension

– AdhesionAdhesion Capillary ActionCapillary Action

Cohesion – An attraction Cohesion – An attraction between molecules of the between molecules of the same substance.same substance.

• Cohesion is the reason why Cohesion is the reason why water forms beads on a water forms beads on a smooth surface.smooth surface.

Surface TensionSurface Tension

• The attraction between water The attraction between water molecules causes a condition molecules causes a condition known as known as surface tensionsurface tension..

Adhesion – is an attraction Adhesion – is an attraction between different substances. between different substances. • Adhesion powers a process called Adhesion powers a process called

capillary actioncapillary action, in which water , in which water molecules move upward through a molecules move upward through a narrow tube, such as the stem of a narrow tube, such as the stem of a plant.plant.

WATER – WATER – It does a body GOOD!!!It does a body GOOD!!!

• Nearly 65-70% of your body is Nearly 65-70% of your body is made of water, water helps move made of water, water helps move nutrients and other substances nutrients and other substances into and out of your cells.into and out of your cells.

• Hydrophilic – Used to Hydrophilic – Used to describe molecules or describe molecules or molecular groups that are molecular groups that are attracted to water and attracted to water and other polar solvents.other polar solvents.

• Hydrophobic – Used to Hydrophobic – Used to describe molecules or describe molecules or molecular groups that mix molecular groups that mix poorly with water. poorly with water. Hydrocarbons and fats are Hydrocarbons and fats are hydrophobic. hydrophobic.