1. Water Chemistry
H2O

3. Valence Electrons: the electron(s) in the outer shell of an atom’s electron cloud, which can combine with other atoms to form molecules *The number of valence electrons in an atom of an element determines many properties of that element, including the ways in which the atom can bond with other atoms.

5. Chemical bonds hold molecules together
Chemical bonds hold molecules together . A chemical bond is a union between atoms formed when they give up, gain, or share electrons .

6. 3 types of bonds
Ionic
Covalent
–Non-polar
–Polar
Hydrogen

7. Ions
Ions: When an atom loses an electron, it loses a negative charge and becomes a positive ion. When an atom gains an electron, it gains a negative charge and becomes a negative ion.

8. Ionic Bonds Description
•Ionic Bond: give up or gain electrons
The resulting oppositely charged ions attract one another, forming an ionic bond.

9. Ionic Bonds
You and a friend walk past a market that sells apples for 40 cents each and pears for 50 cents each. You have 45 cents and want an apple. Your friend also has 45 cents but wants a pear.

10. Ionic Bonds Example
For example, in table salt (sodium chloride) the negative chlorine ion attracts the positive sodium ion, forming an ionic bond.

11. Covalent Bonds Descriptions
A covalent bond shares one or more pair of electrons
Non-polar covalent bond: atoms share electrons equally
Polar covalent bond: atoms share electrons unequally

12. Covalent Bonds Examples.
Covalent Bonds Examples
For example, carbon dioxide molecule is a nonpolar molecule because of its straight-line shape.

13. Covalent Bonds
An example of a polar molecule is water because of its bent shape.

14. Hydrogen Bonds Description
Hydrogen Bonds: form when partial opposite charges in different polar molecules attract each other. These are weak bonds.

15. Hydrogen Bonds Example
The only example of
hydrogen bonding is when
two or more water molecules
are attracted.
One water molecule can attract
up to 4 other molecules.

16. Structure and Properties of Water
Water Flashcards
Structure and Properties of Water
Draw a picture
Take notes (black)
Interesting facts (in blue) --- not required to know

17. Structure of Water Polar Covalent Bonds H2O
 H2O
Electrons are shared unequally
Oxygen is negative (O: -)
Hydrogen is positive (H: +)
Stronger pull towards Oxygen (larger atom)
Hydrogens repel each other.

18. Structure of Water Hydrogen Bonds Water to Water
Water to Water
Hydrogen (+) is attracted to Oxygen (-)
1 H2O can attract 4 H2O’s

19. Properties of Water 3 Phases Solid, Liquid, Gas
Solid, Liquid, Gas
Unique - only substance that can exist in all 3 states of matter naturally on Earth.
Can exist in all 3 states of matter and the exact same time in the same place.

20. Stabilize Temperature
Properties of Water
Stabilize Temperature
High Specific Heat
Water resists temperature changes
Can absorb or release large amounts of heat energy
Heat of Vaporization
In order for water to evaporate hydrogen bonds
must be broken.
When water evaporates it removes a lot of heat with it.
This is why sweating works to cool down.

21. Properties of Water Universal Solvent Dissolves
Dissolves
Water is a polar molecule which attracts + and – ions.
Water dissolves salt (Na+ Cl-)
Dissolves more than anything else (including acids)

22. Properties of Water Density Freezing water Water’s density is 1 g/cm3.
Freezing water
Water’s density is 1 g/cm3.
Water’s density decreases () as temperature decreases ()
Freezes = molecules spread slightly apart creating spaces between them.
Ice floats in liquid water.
This is also why fish and plants in a pond or lake do not die every winter.
Bodies of water freeze from the top down and never all the way through.

23. Properties of Water Transparency Visible Light
Visible Light
Light can penetrate making photosynthesis possible
It is transparent because it doesn’t absorb light
in the visible spectrum
Why is the ocean blue? And a cup of water clear?
Cup – not enough molecules to absorb light
Ocean – water molecules strongly absorb long-
wavelength colors at the red-end of the spectrum,
blue light is then reflected.

24. Properties of Water Cohesion Surface Tension Sticks to itself
Surface Tension
Sticks to itself
Water is polar = “sticky”
The molecules at the surface do not have other like molecules on all sides so they stick together more strongly creating a “film.” These surface molecules are only pulled in a downward direction.

25. Properties of Water Adhesion Capillary Action
Capillary Action
Water sticks to other surfaces.
Like a straw, capillary action is the rise of a liquid that wets the diameter of a small tube.
This climbing effect is created because the water adheres to another surface, but also the cohesive force of water “tows” other water molecules up the surface.
This is why tall trees do not die at the top. They bring water up from the ground.