1. Atomic Models

2. Early Greek Theories fire air water earth
350 B.C - Aristotle
Theory that matter was made of four “elements”: earth, fire, water, air.
Aristotle
Aristotle was wrong. However, his theory persisted for 2000 years.
fire
air
water
earth
Democritus
400 B.C. - Democritus thought matter could not be divided indefinitely.
This led to the idea of atoms.

3. John Dalton 1800’s Proposed an Atomic Theory which states;
All matter is made of atoms.
Atoms of an element are identical.
Each element has different atoms.
Atoms of different elements combine in constant ratios to form compounds.
Atoms are rearranged in reactions.
Jelly beans

4. The Electron Late 1800’s J. J. Thomson
A gas beam was repelled away by a magnet.
The gas is made of atoms, so….
atoms must contain CHARGED particles!
Magnet
The beam wad repelled (away)

5. Thomson’s atomic model
Thomson found that there were small electrons embedded in the atom like chocolate chips in a chocolate chip cookie.
Atoms are solid spheres made-up of a solid positive mass (cookie) with tiny negative particles embedded in the positive core
Negative electrons
Positively charged cookie.

6. Rutherford & the Nucleus
1908
Discovered by his famous ‘gold foil’ experiment.
He shot positively charged particles at a very thin piece of gold foil.
He expected the particles to go right through. Most did go through or got deflected.
But a few BOUNCED BACK!
THEY HIT SOMETHING SOLID!

7. Rutherford’s gold foil experiment
This proved that:
the atom had a dense but very small positive core
the electrons were far away from the nucleus
Most of the atom is just EMPTY SPACE!

8. That would be like a basketball (nucleus) on the 50 yard line, and you were an electron in a seat way up in the stands.

9. Neils Bohr Early 1900’s Electrons move in orbits, energy levels
Electrons in Definite energy Levels around  the nucleus
Electrons can move to
different energy levels if
they gain or lose energy.

10. Quantum Mechanical Model or Electron Cloud Model
Electrons move around the nucleus very fast.
You can’t predict where an electron will be at any moment.
The analogy here is that of a "beehive" where the bees are the
electrons and they ‘buzz’ around the nucleus.             

11. Atoms and elements

12. Atomic Structure

13. Matter…. Is Everything! It’s the amount of mass in an object
Measured in kilograms
It has volume: takes up space
Measured in milliliters or cubic centimeters
All matter is composed of elements
88 natural elements

14. Elements are… Purest of the pure substances
There are 112 of them known so far
They are organized on the Periodic Table
The most common elements:
1. oxygen. ( air, water, rock, living things)
2. Hydrogen (water, living things, sun, stars)
3. Nitrogen (air 80%, living things, soil)
4. magnesium, iron, aluminum, carbon

15. Every element on the periodic table is assigned a box with specific information in it.

16. CF C F Cf Not correct!!! Atomic Symbol 1 or two letter symbol
First letter is always CAPITOL, second letter always lower case.
Co (cobalt) is not same as CO (carbon monoxide)
Examples:
C for carbon
Ca for calcium
Cl for chlorine
Cf for californium
CF C F Cf
Not correct!!!

17. Atoms Smallest part of an element.
Too small to be seen.
All atoms are made of the same basic ‘ingredients’
Atoms vary in size and mass.
Atoms are made up of:
Protons (+ charge)
Electrons (-charge)
Neutrons (neutral)

18. Proton Dense, positively charged particle
There are equal # of protons and electrons in a neutral atom.
Proton’s mass = 1 amu
Proton # is their Atomic number.
Ex: 6 protons is element 6 or carbon
+ = -

19. Neutron Difficult to ‘find’ because they have no charge
Same mass as a proton (1 amu),
but has NO CHARGE (neutral)
Neutrons are in the nucleus. No
charge

20. + Neutral atoms = Ex: chlorine 17 protons 17 electrons -
Since protons are positively charged
And electrons are negatively charged,
A neutral atom has EQUAL # protons and electrons! =
Ex: chlorine 17 protons 17 electrons + -

21. Mass Number Mass Number = # protons + # neutrons in nucleus
Protons and neutrons make up the mass of the nucleus (and 99.9% of the atom’s mass)
Ex: Chlorine’s mass number is 35
17 protons and 18 neutron = 35

22. Number of neutrons Mass number of uranium 238
Mass number of oxygen 16 atomic number (protons) -8 number of neutrons 8
Mass number of uranium 238
atomic number (protons) -92
number of neutrons
146
* The number of neutrons in an atom can vary.

23. There are two forms of carbon…
Carbon-12 has
6 protons
+6 neutrons
Total mass = 12
Carbon- 14 has
6 protons
+8 neutrons
________________
Total mass = 14
Carbon-12 and Carbon-14 are Isotopes.
So… what is an isotope?

24. Isotope Atoms of the same element with a different number of neutrons
Same # of Protons
Different # neutrons
Different mass number

25. 3 4 3 6 6 17 35 61 108 47 207 20 Element Number of Protons
Element
Number of Protons
Number of Neutrons
Number of Electrons
Mass Number
Atomic Number
lithium  3  4 3 
carbon 6   6
chlorine
17 
35 
silver
 61
108
47 
Lead
207 
calcium
20 

26. Periodic Table of Elements

28. Dmitri Mendeleev
First Table made by arranging the 63 known elements in order of
atomic weight
grouping them by similarity of properties.
Predicted
the existence of new elements
pointed out that some of the known atomic weights were wrong
He left space on his table for new elements, and predicted yet-to-be-discovered elements

29. Aren’t you glad it
doesn’t look like this now?
This gives me a headache.
Gaps where he knew that missing elements should be.

30. The Modern Periodic Table
What season comes after our current season? After that?
The periodic tables has:
Horizontal Rows (label these from top to bottom #’s 1 through 7. The row number corresponds to how many energy levels the atom in that row have.)
These rows show TRENDS!
For example, as you move across a row, elements go from metallic to less metallic.
When you finish a row, the next row repeats those properties. Just like the seasons repeat themselves year after year.

31. MORE about the P.T. !
What are some things you have in common with your family?
The periodic table also has COLUMNS. They are called:
Groups or Families –
Elements in the same group have similar physical and chemical properties

32. More about Groups on the P.T.
The groups can be labeled 1 through 18 (most modern way)
or 1A, 1B, 3B, 4B, etc. (old-fashioned)
Groups with an A have a “little of everything” metal, non-metal, reactive, non-reactive
Groups with a B are “transition metals” and pretty much alike.

34. METALS Hey! Label your table! Nonmetals Metalloids H He Li Be B C N O1 He 2 1 Li 3 Be 4 B 5 C 6
Nonmetals N 7 O 8 F 9 Ne 10 2 Na 11 Mg 12 Al 13 Si 14 P 15 S 16 Cl 17 Ar 18 3 K 19 Ca 20 Sc 21 Ti 22 V 23 Cr 24 Mn 25 Fe 26 Co 27 Ni 28 Cu 29 Zn 30 Ga 31 Ge 32 As 33 Se 34 Br 35 Kr 36 4
METALS Rb 37 Sr 38 Y 39 Zr 40 Nb 41 Mo 42 Tc 43 Ru 44 Rh 45 Pd 46 Ag 47 Cd 48 In 49 Sn 50 Sb 51 Te 52 I 53 Xe 54 5
Metalloids Cs 55 Ba 56 Hf 72 Ta 73 W 74 Re 75 Os 76 Ir 77 Pt 78 Au 79 Hg 80 Tl 81 Pb 82 Bi 83 Po 84 At 85 Rn 86 6 Fr 87 Ra 88 Rf
104 Db
105 Sg
106 Bh
107 Hs
108 Mt
109 7 La 57 Ce 58 Pr 59 Nd 60 Pm 61 Sm 62 Eu 63 Gd 64 Tb 65 Dy 66 Ho 67 Er 68 Tm 69 Yb 70 Lu 71 Ac 89 Th 90 Pa 91 U 92 Np 93 Pu 94 Am 95 Cm 96 Bk 97 Cf 98 Es 99 Fm
100 Md
101 No
102 Lr
103

35. And color code, too! Come get three colored pencils but you don’t’ have to use these offensive colors. 1 2
Nonmetals 3 4 5
Metals 6 7
Metalloids
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 349

36. Properties of Metals, Nonmetals, and Metalloids
malleable, lustrous, ductile, good conductors of heat and electricity
NONMETALS
gases or brittle solids at room temperature, poor
conductors of heat and electricity (insulators)
METALLOIDS
(Semi-metals)
dull, brittle, semi-conductors (used in computer chips)

37. Periodic Trends Wow! Can’t you just wait?
The periodic table shows all sorts of trends, but we will keep it very basic.

38. Atomic size (radius)
The size of the atom increases as you go down the table.
Size decreases as you go across.

40. Electronegativity - the tendency of an atom to attract electrons

41. Ionization Energy -  the amount of energy required to remove an electron from the atom or molecule

42. Electron Affinity -  the amount of energy released when an electron is added to a neutral atom or molecule to form a negative ion.

43. Melting/Boiling Point
Highest in the middle of a period.

44. The elements get more metallic as you go down the table, and less metallic as you go across.