1. 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 and Ionic Bonds
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. Ions and Ionic Bonds
•Ionic Bond: An atoms gives up or gains one or more of its electrons to another. The resulting oppositely charged ions attract one another, forming an ionic bond.

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

11. Covalent Bonds
A covalent bond holds together two atoms that share one or more pair of electrons
Electrons in a covalent bond may be equally or unequally shared between the atoms.
Non-polar covalent bond: atoms share electrons evenly
Polar covalent bond: atoms share electrons unequally

12. Covalent Bonds
Those atoms with greater positive nuclear charge pull more strongly on electrons in a covalent bond.

13. .
For example, carbon dioxide molecule is a nonpolar molecule because of its straight-line shape. An example of a polar molecule is water because of its bent shape.

14. Covalent Bonds H2O (the molecule – NOT water) is a polar molecule
–The (slightly) positively charged pole is around each hydrogen
–The (slightly) negatively charged pole is around the oxygen

15. Hydrogen Bonds Hydrogen Bonds: form when partial opposite
charges in different polar
molecules attract each other.
Polar molecules have partially charged atoms at their ends.
Individual hydrogen bonds are rather weak, but collectively (together), they are quite strong.

16. Hydrogen Bonds 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.

17. Graphic Organizer Polar Covalent Bond Nonpolar Covalent Bond
Hydrogen Bonds
Feature
Ionic Bond
Attraction between oppositely charged ions
Partial opposite charges in different polar molecules
How Bond Forms
Unequal sharing of electrons
Equal sharing of electrons
Charge on Bonded Atoms?
Yes, slightly positive or slightly negative
Yes; positive or negative
Yes; positive or negative No
H2O molecule (or other polar covalent molecule)
NaCl crystal (or other ionic compound)
Example
Two or more H2O molecules
O2 molecule