Water and Its Properties

The Earth’s Fresh Water

· Almost 75% of Earth is covered by water

· 97.2% of the water is Salt Water

· 2.8% of the water is Fresh Water

o 2% is frozen in glaciers and ice caps

o 0.6% lies underground

o 0.001% is in atmosphere

o rest is on the surface or in soil moisture

Properties of Water

· Only compound that occurs in all 3 phases at normal Earth temps (solid, liquid and gas)

· Each water molecule has: 2 H (hydrogen) atoms and 1 O (oxygen) atom

· Water is a polar molecule- it has a slight electric charge

o H have a slight positive charge

o O’s have a slight negative charge

Physical Properties

· Surface tension occurs because water molecules attract each other

o gives water droplets a rounded shape

· Ice is less dense than liquid water

o usually solids are more dense but polar water molecules can’t get very close together

o Water is most dense at 4°C

Chemical Properties

· Water is a universal solvent

o Can dissolve more substances that any other liquid

· Substances made of polar molecules can easily dissolve in water

· Substances made of nonpolar molecules are insoluble in water

The Water Cycle

· Water moves continuously from one place to another due to the water cycle