1. Chapter 2 part 1

2. Law of conservation of mass
Dalton
Mass is neither created or destroyed in chemical rxns.

3. Law of definite proportions
Dalton
In a given compound the relative number and kind of atoms is constant.
Example: Water = 2 H and 1 O

4. Law of multiple proportions
This law is readily explained by Dalton's atomic theory. Suppose a compound is made of element A and element B, giving the formula AB. Since the weight of A is constant and the weight of B is constant, the A:B weight ratio will always be the same.
Pg 45 in text (MOVIE)

5. Law of multiple proportions
when elements combine, they do so in the ratio of small whole numbers

6. Dalton’s Atomic Theory
each element is composed of atoms
All atoms of a given element are identical
A chemical compound is the result of the combination of atoms of 2+ different elements
Atoms of an element are not changed into different types of atoms by chemical rxns
(MOVIE)

7. Millikan Discovered the charge and mass of an electron
1.6 X C (coulomb)

8. Radioactivity Three types of radiation Alpha α +2 charge
Gamma γ no charge
Beta β charge

9. Rutherford
Most of the mass of an atom and all of its positive charge resides in a very small dense region (nucleus)
Most of the volume of the atom is empty space around the nucleus

11. Atomic Structure Proton Symbol p+ Charge = 1.602 x 10-19 C (coulomb)
Mass = amu
Electron
Symbol = e-
Charge = x C
Mass = x 10-4 amu
Neutron
Symbol = n0
no charge
Mass = amu

12. Units = amu or g/mol

13. Complete Chemical SymbolZ X
A = Atomic mass ( p+ n)
Z = Atomic number ( p)
X = element Symbol

14. Question How many neutrons, protons and electrons are in carbon?12 6
C = Carbon
12 = Atomic Mass ( protons + neutrons)
6 = atomic Number (protons)

15. Answer 12 = p + n 6 = protons 12 – 6 = 6 neutrons
In an atom with out a charge the number of protons is equal to the number of neutrons
Thus: 6 electrons

16. Question
Write the complete chemical symbol for the following elements.
Magnesium
Sodium
Tungsten

17. Determining Sub Atomic Particles12 6 C
C = Carbon
12 = Atomic Mass/weight ( protons + neutrons)
6 = atomic Number (protons)

18. Isotopes Isotopes Isotope Protons Electrons Neutrons 11C 6 5 12C
Atoms of a given element that differ in number of neutrons and thus in mass.
Isotope
Protons
Electrons
Neutrons
11C 6 5
12C

19. Isotopes Cont.
When writing isotopes the atomic number ( # of p+) stays the same, but the Atomic Mass (p+ + n0) changes due to the addition and subtraction of neutrons.

20. Formulas
Chemical Indicates actual numbers and type of atoms in a molecule
H2O C2H4
Empirical gives only relative number of atoms of each type
HO CH2
Structural individual bonds are shown, indicated by lines

21. average atomic mass Amu = Average Atomic Mass Unit
The average atomic mass (weight) of an element is equal to the sum of the products of each isotope’s mass (in amu) multiplied by it’s relative abundance.

22. EXAMPLE OF AVERAGE ATOMIC MASS PROBLEM
Naturally occurring chlorine is 75.53% Cl-35 which has an atomic mass of amu, and 24.47% Cl-37, which has an atomic mass of amu.
Calculate the average atomic mass of chlorine.

23. EXAMPLE OF AVERAGE ATOMIC MASS PROBLEM (CONT)
Average atomic Mass = [ (%/100) (Atomic Mass) ]
Average atomic mass = (0.7553) ( amu) + (0.2447) ( amu)
= amu amu
= amu
NOTE: The average atomic mass of an element is closest in value to the atomic mass of the most abundant isotope.

24. Halogens
Alkali metals
TRANSITION METALS
Alkaline Earth Metal
Metalloids
Metals
Non Metals

25. DIATOMIC SEVEN

26. Nomenclature Chapter 2 part 2
Check out these videos for more help or if you are absent
Naming molecular compounds
Writing formulas for molecular compounds
Naming ionic compounds video
Writing formulas for Ionic compounds

27. 2.7 Ions and ionic compounds
When negative electrons are removed or added to an atom the charge of that atom changes from its neutral state to a charged state ( + or - )
Ion: charged particle

28. a cation is a particle that carries a positive electrical charge
a cation is a particle that carries a positive electrical charge. The cation gets this positive charge from losing negatively charged electrons.

29. Anions are ions that carry a negative electrical charge
Anions are ions that carry a negative electrical charge. Anions get their negative charge by gaining one or more electrons

30. Trick
Cl-
Na+

31. Example Na = atomic number 11 atomic mass = 23
11 protons, 12 neutrons, 11 electrons
Na- = 11 protons, 12 neutrons, 12 electrons
We added an additional negative charge (e-) creating a negatively charged particle.
= -1 charge on Na

32. Reverse example Na = atomic number 11 atomic mass = 23
11 protons, 12 neutrons, 11 electrons
Na+ = 11 protons, 12 neutrons, 10 electrons
We subtracted a negative charge (e-) creating a positively charged particle.
= +1 charge on Na

33. Question How many protons and electrons does Se2- ion posses?
How many protons and electrons does Cr3+ ion posses?
What kind of ions are these molecules and why?

34. Answer Se2- : anion 34 protons (atomic number)
36 electrons = = -36
Cr3+ :
Cation
24 protons (atomic number)
21 electrons = 24 – 3 = 21

35. Nomenclature (Naming)
As of 2007 there are 31,000,000 known compounds.
Your are options are
A: memorize all 31,000,000 names
B: Learn how to name them memorize about 50 things that will allow you to name all 31,000,000.

36. Polyatomic Ions
Atoms joined as a molecule, but they have a net positive or negative charge.
Example:
NO3-, SO42-
I will give you a list. You need to try to memorize them all… yes all.

37. Polyatomic Ion Rap

38. Cation and Anions to Memorize
+/-3 +/-4
Write these on your binder periodic table

39. Putting the pieces together
Na Cl Mg Cl-
NaCl is an ionic compound
MgCl2 is an ionic compound

40. Ionic Compounds Contain both positively and negatively charged ions.
In general ionic compounds are made of metals and nonmetals.

41. Covalent compounds
2 negatively charged elements
2 non metals

44. Question Write the ionic compound for: Magnesium and Nitrogen
Magnesium and NO3-

45. Answer
Mg3N2
Mg(NO3)2
Count the total number of each type of atom in the molecules above.

46. Homework
Pg 71
#’s 37,40,45,47,48

47. 2.8 Naming ionic compounds
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