Properties of Water Mr. Luis A. Velázquez

What is water?  Water also known as H 2 O is a molecule.  Water is made of non-metals.  Water is made out of two diatomic molecuels. H 2 & O 2

Properties of water  The attraction between water molecules is called cohesion.  The attraction of the water molecule to other materials, like glass or soil, is called adhesion.  These also cause surface tension and capillary action.

Water has a high surface tension  Because water is a polar molecule; it easily attracts other water molecules.  This attraction causes the surface layer of water molecules to act as a stretched film over the surface of the water.  This property is known as surface tension.

Capillary Action  Plants also take advantage of the great attraction water has for itself and other molecules.  In fact, it is this property of water that allows plants to get water from the ground. Water creep up the thin tubes in plant roots and stems

Water has a high heat of vaporization  Because water strongly attracts other water molecules; it takes a lot of energy to make water evaporate.  As water heats, its molecules vibrate faster and faster. As more heat is applied, surface molecules begin to separate from the rest and evaporate in to the air.  This high heat of vaporization helps cool the human body. When sweat evaporates from the human skin, its draws away the heat of vaporization from the body itself, thus helping keep the body cool.

Resistance to change  Water resist temperature changes.  Water requires more heat to increase its temperature than do most other common substances.

Water expands when it freezes  Water is one of the few substances that expand when it freezes.  Because of this property, ice is less dense than liquid water and floats as it forms in a pond.

Polar Molecule  Water is consider a polar molecule.  This means that water molecule has two poles. ( Positive & negative)  Water is made of two atoms of hydrogen and one of oxygen.  Hydrogen behave as a positive pole.  Oxygen behaves as a negative pole.

Hydrogen Oxygen What is a polar Molecule?

Interesting information  Water is the most common liquid in the world.  Water makes up 78% of the human body.  70% of the Earth is cover with water.  When water reach the temperature of 38  F water expands 9%  Water is considered the universal solvent can dissolve almost every thing in earth.