Lecture: Atomic Structure intro to: “structure of an atom”

http://www.youtube.com/watch?v=TBrJt-5LHgQ&safety_mode=true&persist_safety_mode=1&safe=active

intro to structure of an atom : “Electrons, Protons And Neutrons | Standard Model Of Particle Physics”

 http://www.youtube.com/watch?v=Vi91qyjuknM&safety_mode=true&persist_safety_mode=1&safe=active

You will need a paper copy of the periodic table for this

unit and its exam

Draw this:

l. Atomic structureA. atom

1. smallest particle of an element which retains its characteristic properties, tear aluminum foil?

2. the fundamental unit of matter (definition?)How does this relate to the atom: ?

-building block from which all matter is made: brick house?

3. has NO CHARGE!!!4. based on Rutherford’s planetary model:

radioactive danger symbol: -mostly empty space = a marble in a football

coliseum?5. two regions: ?

a) nucleus and b) electron cloud

a. nucleus-has two subatomic particles ?:

protons and neutrons

1. protons: + charge (battery?),

-equals the atomic #:

-which defines the element/makes it unique: no other # on the periodic table of elements

-has 1 amu of mass: based on the average mass of carbon’s isotopes

2. neutrons: no charge

- has 1 amu of mass

- #protons + #neutrons = atomic mass

99.999% of an atom’s mass is in the nucleus, E=MC2 ?

Atomic # ?# protons ?Atomic mass ?# neutrons ?# + charges ?# - charges?

3. Nuclear decay:-occurs when the atom is not stable:

nucleus breaks apart, many types of decay-occurs when the proton/neutron count is “off”:

meaning it varies from norm, thus unstable-a product of the nuclear decay can be an energy emission: radiation, or a matter emission: p or n-Alpha decay: ejects 2 protons and 2 neutrons: ?changes the atomic number and thus the element and mass:

-radon gas comes from the decay of U238 thorium radon lead (many of our homes in Boulder!)

-radon is deadly in your lungs due to the mass emissions (protons=mass!!)

-Beta decay: neutron splits into both a proton and electron-

it keeps the proton (changes element, why?)

and ejecting the electron. Mass stays same, why?

-Gamma decay: alpha and beta decay almost always are joined by:

emitting very high frequency and high energy waves from the electromagnetic spectrum called gamma rays

b. electron cloud

- made of electrons moving at almost the speed of light, thus

also called the electron cloud: fuzzy images

- negative charge

- # electrons = # protons , why?

(right: because all atoms have no charge)

-opposite charges hold the atom together, which particles ?

- almost no mass

6. if change # p : change ?

if change # n : change ?

if change # e : change ?

7. use your periodic table to fill in:

Pa Ca

# p ? ?

# n ? ?

# e ? ?

amu ? ?

6. if change # p : change ?

if change # n : change ?

if change # e : change ?

7. use your periodic table to fill in:

Pa Ca

# p 91 20

# n 140 20

# e 91 20

amu 231 40

Examples:

Iron: 26Fe56

#p, # e, at mass, # neutrons?

+1(called?): 26Fe56+1 : #e =?

Carbon: 6C12

#p, #e, at mass, # neutrons?

-1(called?): 6C12 -1 : #e =?

Potassium: 19K39

#p, #e, at mass, # neutrons?

+2 (called?): 19K39+2

: #e =?

-Bohr atom: like the planetary model, but that is actually incorrect: e- are dynamic and w/ overlapping orbitals1. electrons occur only at specific energy levels = n,

vacuum in between2. e- farther from nucleus have more energy

e- held to atom by a + nucleus (opposites attract),

outer ones less so due to e- shielding3. e- have no specific location w/in shell, only probable

occurrence: cloud-like4. specific # e- occur in each energy level

a. maximum # per shell = 2n2 (n = shell #)shell # 1 = ___shell # 2 = ___shell # 3 = ___shell # 4 = ___

Where are shells 6 and 7 ?:

- Because of “back filling” and s,p,f,d sub shells, incomplete filling of the energy levels (not maximum) can vary but largely follows this format:- Level 1 = 2- Level 2 = 8- Level 3 = 8- Level 4 = 18

-When electrons become energized theybecome excited and move farther away from the nucleusinto outer energy levels:

See drawing next page:

draw this, note the axis:

-Electrons out of their normal energy level are unstable and

release energy in the form of light then

return to their normal energy level

-The color of the light emitted depends on

which energy level they “fall back from”:

-high energy (outer): has short wave length: violets

-low energy (inner): has long wave length: reds

-Elements will emit their own different patterns of colors called a spectrum: fire works?

-Every element has its own unique color spectrum

-The elemental color spectrum is a characteristic property (ie: specific heat, density, solubility, flammability, mp, bp etal)

C. Ions: charged “particle” (atom?)1. atoms can gain or lose electrons2. when they do they are now charged and thus cannot be called an atom: why ?3. same # protons as original element/atom4. different # electrons5. mass ?6. + (positive) = cation: gain or lose e-?

Na+1, how many electrons?7. - (negative) = anion: gain or lose e-?

Cl -1, how many electrons?8. NaCl is a neutral compound because:

Na +1: lost an electronCl -1: gain an electron

D. Isotopes

1. not all atoms of the same element are identical, ie dogs

2. some have a different # of neutrons,

but the atomic # (#protons) are the same, why?

3. what is the charge?

4. thus, the atomic mass is different

5. some isotopes are unstable:

decay and emit radiation:

radioactive isotopes:

C14 decays into C12

E. Atomic behavior is very unusual and is referred to as quantum theory:

Due to their small size, they no longer can be explained by classic physics, instead

their values are restricted to specific amounts:

energy and momentum

F. Along the same lines as quantum theory is the uncertainty principle:

due to its dynamic state,

subatomic particles cannot be fully observed and described simultaneously, thus

there is a degree of uncertainty of the particles’ attributes:

time, position, energy and momentum