Basic Chemical Bonding
and
Properties of Water
TEKS
Vocabulary
• Valence electron
• Cohesion
• Adhesion
• Polar/Polarity
• Hydrogen Bonding
• Hydrophilic
• Hydrophobic
Prerequisite Questions
• What is the chemical formula for water?
• What are the 3 states of water called?
• What happens to a chemical when moves from one state of matter to
another?
• What can you state about two oppositely charged particles?
Periodic Table Trends
Octet Rule
• Atoms feel electrically more comfortable with a full outer valence
shell
Salt as an example
• Sodium wants to give up its outer most valence because then it has a
full “inner” shell.
• Chlorine wants to steal one more electron because then its shell is full
Lewis Dot
• We only need to look at the valence electrons because they are
involved in bonding
Na
Basic Bonding concepts
• Covalent bonds form between the sharing of valence electrons
connecting different atoms.
4 Emergent Properties of Water
1)
2)
3)
4)
Water has a molecularly attractive nature (Cohesive and Adhesive)
Water has a high specific heat
Water is less dense as a solid (ice)
Water is the universal solvent
Water is a polar molecule
• The electrons in a water molecule spend more time around Oxygen
then the two Hydrogens.
• That makes water’s oxygen slightly more negative and the hydrogens
slightly more positive
Cohesion of Water molecules
• Because opposites attract, the hydrogens of one molecule attract to
the oxygens of other water molecules.
• This attraction between water molecules is Cohesion.
Adhesion of Water molecules
• When water molecules are attracted to other polar, non-water,
molecules it is called Adhesion.
Specific Heat of Water
• Water has a high specific heat.
• That means it can absorb a lot of energy before it changes states.
• It is good at regulating temperatures in organisms and ecosystems
Solid Water is Less Dense than liquid water
• Ice floats on liquid water
Universal Solvent
• Because water is POLAR it is very effective at grabbing other polar
molecules and moving them around
Concept Mastery Questions
• Why does water stick to other molecules?
• Why doesn’t water mix with oils/lipids?
• What would happen to life on Earth is water was more dense as a
solid?
• How does water aid in thermal regulation?
Practice Questions (optional)