Chapter 2 Section 2
Properties of Water
The Water Molecule…
• The chemical symbol for water is H20.
– This means the molecule consists of 1 Oxygen
atom and 2 Hydrogen atoms.
– The Oxygen and Hydrogen atoms share electrons.
• The Oxygen shares one electron with each hydrogen
atom.
• Thus water is a covalent molecule.
The Water Molecule…
• A water molecule is considered to be Polar.
– A polar molecule is a molecule in which the
charges are unevenly distributed.
The Water Molecule…
• Because water molecules are polar they can
attract each other.
– These attractive forces are called hydrogen bonds.
• They are not as strong as covalent or ionic bonds.
• A single water molecule can be involved in up to 4
hydrogen bonds at the same time.
– The attraction between molecules of the same
substance is called cohesion.
– When molecules of different substances are
attracted that is called adhesion.
Solutions and Suspensions…
• A mixture is a material composed of two or
more elements or compounds are physically
mixed but not chemically combined.
– Water can form two types of mixtures.
• Solutions
• Suspensions
Solutions and Suspensions…
• Solutions are mixtures whose components
are evenly distributed thourghout.
– Solutes are the substances being dissolved.
– Solvents are the substances in which the solute is
dissolved.
Solutions and Suspensions…
• Suspensions are mixture of water and
undissolved solids.
Acids, Bases, and pH…
• The pH scale is a measurement system used
to indicated the concentration of H+ ions in a
solution.
– The pH scale ranges from 0 to 14.
• Acids are compounds that form H+ ions in a
solution.
– They are located on the pH scale at values under 7.
– Strong acids are usually found between 1 to 3
• Bases are compounds that produce OH- ions in
solution.
– They are located on the pH scale at values over 7
– Strong bases are usually found between 11 to 14.
Acids, Bases, and pH…
• Buffers are weak acids or bases that can react
with strong acids or bases to prevent sharp,
sudden changes in pH.
– They are an important part of homeostasis.