1. Atomic Theory & Atomic Structure Atoms: The Building Blocks of Matter

2. ATOMS = BUILDING BLOCKS
Atoms- the smallest particle of matter which will exhibit the properties of that element.
ATOMS = BUILDING BLOCKS Mg Na H

3. How small is an atom?

4. The scale of things- Biggest Big Small Smallest Universe Galaxy
Planetary
Systems
Planets
Big
Biospheres
Ecosystems
Populations
Small
Organisms
Systems
Organs
Tissues
Smallest
Cells
Cell Organelles
Macromolecules
Molecules
Elements
Atoms
Wow! All of that is possible because of atoms.

5. When atoms are broken down,
the parts (protons, electrons, and neutrons)
of different elements look the same!
That’s why we say that the atom is the smallest particle that retains it’s own unique properties.

6. Draw this…
}nucleus
Neutron (n0)
Proton (p+)
Electron (e-)

7. Mystery Box
try to figure out what is inside the “Mystery Box” WITHOUT OPENING IT!!!! 

8. Atomic Model of Matter
In order to develop the atomic theory of matter, scientists used indirect evidence without seeing or touching the object but relied on how matter behaves. This was WAY before technology actually allowed us to “SEE” an atom! 

9. Historical Development of the Atom (Atomic Theory)
How did we discover atoms and all its parts?

10. HISTORICAL DEVELOPMENT
Democritus- 400 B.C.- atoms were first suggested by Democritus, an ancient Greek and student of Aristotle. Aristotle rejected this theory and claimed that his theory of matter being infinitely divisible and continuous in nature were correct.

11. John Dalton (1808)

12. John Dalton (1808)
British chemist who was the first to have a theory about matter being composed of atoms and how these atoms might look and behave.
He conceived of the atom as a solid billiard ball.

13. Dalton’s Model of the Atom
DRAW THIS IN YOUR NOTES!!
SOLID BALL OF MATTER (no protons, neutrons, or electrons!)

14. Dalton's Atomic Theory (Daton’s Postulates):
All elements are composed of atoms that are indivisible.
All atoms of the same element are identical.
3. Atoms of different elements are different (they have different numbers of protons, and they MAY also differ in mass numbers).

15. Dalton's Atomic Theory (Dalton’s Postulates):
4. Atoms of different elements can combine with each other in simple whole number ratios to form compounds.
Chemical reactions occur when atoms are separated, joined, or rearranged. However, atoms of one element ARE NOT changed into atoms
of another element
by a chemical
reaction.

16. J. J. Thomson (1903)

17. J. J. Thomson
Thomson was a British chemist who discovered the electron with the cathode ray tube experiment!
He was the first to discover one of the subatomic particles in the atom!

18. Thomson’s Model of the Atom
DRAW THIS IN YOUR NOTES!!
“Plum Pudding” or “Chocolate Chip Cookie Dough” Model.
A ball of positive charge containing a number of electrons.

19. J. J. Thomson Cathode Ray Tube Experiment:
Thomson shot an electrical charge through a cathode ray tube. He saw that the particles deflected towards the positive end of the tube. This meant that atoms contained a negative charge!

20. Ernest Rutherford (1911)

21. Ernest Rutherford- 1911
discovered the nucleus with the gold foil experiment and realized that
The main part of the atom’s mass is in the nucleus
The nucleus has a positive charge.
Atoms are mostly empty space except for the nucleus.

22. Rutherford’s Model of the atom
DRAW THIS IN YOUR NOTES!!
Empty Space
Postively-charged Nucleus
Negatively-charged Electrons

23. Ernest Rutherford Gold Foil Experiment:
Shot alpha particles (positively-charged particles) at a sheet of gold foil. Saw that most particles pass through the foil and some deflected straight back at different angles. This meant that the atom is MOSTLY EMPTY SPACE with a positively-charge nucleus.

25. Niels Bohr (1913)

26. Neils Bohr
was a student of Rutherford and believed that the model needed some improvement. Bohr proposed that an electron is found only in specific circular paths, or energy levels, around the nucleus.

27. Niels Bohr In the Bohr model:
1) each electron has a fixed energy called an energy level.
2) The lower the level, the lower the energy, the closer to the nucleus.
3) An electron cannot exist between energy levels.

28. Bohr’s Model of the atom
DRAW THIS IN YOUR NOTES!!
Nucleus
Electrons
(orbiting the
nucleus)

29. Neils Bohr
In the Bohr Model, to move from one energy level to another, an electron must gain or lose the right amount of energy.
Quantum- the energy required to move an electron from one energy level to another. The energy of an electron is said to be quantized.

30. What are the parts of the atom?
Atomic Structure
What are the parts of the atom?

31. The Atom and subatomic particles-
Protons- positively charged particles inside the nucleus,
Protons DEFINE/IDENTIFY an atom!!!!
Neutrons-neutral particles inside the nucleus
Electrons-negatively-charged particles outside the nucleus

32. Practice: Particle Mass (kg) Mass (amu) Charge p+ 1.67493 x 10 -27 n

33. Parts of the Atom 1. Atomic Number (Z) - #p (number of protons)
2. Mass Number- #p + #n (everything in the nucleus). This is NOT on the P.T.!!!

34. Most atoms are NEUTRAL. This means #p = #e.
But sometimes, the # of protons DOES NOT equal the # of electrons…

35. 3. Ion: A charged atom (#p = #e)
Cation: - POSITIVELY(+) charged atom that LOSES an electron
Anion:
- NEGATIVELY (-) charged atom that GAINS an electron

36. Isotopes
4. Isotope- an atom of the same element that has a different number of NEUTRONS

37. Reading the Periodic Table
Atomic Number (#protons) 6 C
Carbon
12.011
Element Symbol
Element Name
Average atomic Mass (amu)

38. 6C 12 2- Atomic Symbols Charge Mass Number (#p + #n)
(#p - #e)
Mass Number (#p + #n) 6C
Atomic Number (#p)

39. Other Info Mass Number = #p + #n About electrons:
NOT the same as Atomic Mass… you CAN’T find this on the P.T.!
About electrons:
If #e = #p --- NEUTRAL ATOM
If #e = #p --- ION

40. Beans activity A Carbon atom has: Create a “bean atom” of carbon.
6 protons
6 neutrons
8 electrons
Create a “bean atom” of carbon.
Is this atom NEUTRAL? Why or why not?
What is the charge of this atom?

41. Beans activity A different Carbon atom has:
6 protons
7 neutrons
8 electrons
Create a “bean atom” of carbon.
What is different about this atom?
What is it called when two atoms of the same element have different number of neutrons?