1. What is the chemical formula for water. Draw the structure of water
What is the chemical formula for water? Draw the structure of water. Write down all the types of bonding that you know of.

2. What allows this drop of water to hang there without falling?

3. Surface Tension

4. Hydrogen Bonding in Water

5. Chemical Context of Life
Matter (space & mass)
Element; compound
The atom
Atomic number (# of protons); mass number (protons + neutrons)
Isotopes (different # of neutrons); radioactive isotopes (nuclear decay)
Energy (ability to do work); energy levels (electron states of potential energy)

6. Chemical Bonding Covalent Double covalent Nonpolar covalent
Ionic
Hydrogen
van der Waals

7. Covalent Bonding Sharing pair of valence electrons
Number of electrons required to complete an atom’s valence shell determines how many bonds will form
Ex: Hydrogen & oxygen bonding in water; methane

8. Covalent bonding

9. Polar/nonpolar covalent bonds
Electronegativity attraction for electrons
Nonpolar covalent •electrons shared equally •Ex: diatomic H and O
Polar covalent •one atom more electronegative than the other (charged) •Ex: water

10. Polar/nonpolar bonds

11. Ionic bonding
High electronegativity difference strips valence electrons away from another atom
Electron transfer creates ions (charged atoms)
Cation (positive ion); anion (negative ion)
Ex: Salts (sodium chloride)

12. Ionic bonds

13. Hydrogen bonds
Hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom (oxygen or nitrogen)

14. van der Waals interactions
Weak interactions between molecules or parts of molecules that are brought about by localized change fluctuations
Due to the fact that electrons are constantly in motion and at any given instant, ever-changing “hot spots” of negative or positive charge may develop

15. Water Polar~ opposite ends, opposite charges
Cohesion~ H+ bonds holding molecules together
Adhesion~ H+ bonds holding molecules to another substance
Surface tension~ measurement of the difficulty to break or stretch the surface of a liquid
Specific heat~ amount of heat absorbed or lost to change temperature by 1oC
Heat of vaporization~ quantity of heat required to convert 1g from liquid to gas states
Density……….

16. Density Less dense as solid than liquid Due to hydrogen bonding
Crystalline lattice keeps molecules at a distance

17. Acid/Base & pH
Dissociation of water into a hydrogen ion and a hydroxide ion
Acid: increases the hydrogen concentration of a solution
Base: reduces the hydrogen ion concentration of a solution
pH: “power of hydrogen”
Buffers: substances that minimize H+ and OH- concentrations (accepts or donates H+ ions)

18. Two major parts of an atom
Nucleus (not to scale)
Electron Cloud

19. Three Major Sub-Atomic Particles
Protons
Neutrons
Electrons

20. PROTON (p+)
a single, relatively large particle with a positive charge that is found in the nucleus

21. THE PROTON p+
Fat (heavy)
Positive  (charge)
Doesn’t move (lazy)

22. NEUTRON (N°)
a single, relatively large particle with a neutral charge that is found in the nucleus

23. THE NEUTRON N° 
Fat (heavy)
Neutral  (charge)
Doesn’t move (lazy)

24. ELECTRON (e-)
a single, very small particle with a negative charge that is found in a “cloud” around the nucleus

25. e- THE ELECTRON Skinny (very light) Negative  (charge)
Moves a lot (runs around)

26. Review: Subatomic ParticlesN°  e-

27. Please complete the following table
Protons
Neutrons
Electrons
Where are they found?
Mass
Charge (attitude)
Electron Cloud
Nucleus
Nucleus
Heavy
Heavy
Very Light
Positive 
Neutral 
Negative 

28. ATOMIC MASS #
(A)
The total mass of all of the subatomic particles in an atom (but really # of protons and neutrons)

29. ATOMIC NUMBER (Z)
the number of protons in an atom (assuming the atom is neutral, # of p+ = # of e-)

30. Example: Sodium Na Atomic Mass # = p+ & N° 22.99 11
Atomic # = # of protons

31. Another Notation
Atomic Mass # = p+ & N°
Atomic # = # of protons

32. To calculate the number of neutrons, subtract the atomic number (smaller) from the atomic mass number (larger) A – Z = # of neutrons

33. Ex: How many neutrons does Sodium have?
Mass # - Atomic # = #N°
(You may need to round the atomic #)
22.99
= 12 N° Na 11

34. ION
Atoms of the same element that differ in charge. (They have the same # of p+, but different # of e-)

35. Positive Ions (cations)
Negative Ions (anions)
Na+ (lost 1 e-)
Ca2+ (lost 2 e-)
Al3+ (lost 3 e-)
Pb4+ (lost 4 e-)
H+ (lost 1 e-)
Cl- (gain 1 e-)
O2- (gain 2 e-)
P3- (gain 3 e-)
S2- (gain 2 e-)
OH- (gain 1 e-)

36. If an atom GAINS electrons, its overall charge becomes more negative
If an atom GAINS electrons, its overall charge becomes more negative. If it LOSES electrons, its charge becomes more positive

37. ISOTOPE
Atoms of the same element that differ in mass. (They have the same # of p+, but different # of N°)

38. Isotopes are CHEMICALLY the SAME as atoms, but DIFFER PHYSICALLY because they have different masses.

39. A few examples of isotopes…

40. Complete the following table
Protons
Neutrons
Electrons
Na+
Br w/ mass 84
O2- with mass 13