Download Atom Notes

Atom Notes
I.
The atom
A.
B.
C.
D.
II.
1.
negatively charged
2.
small particle
3.
located in orbit around nucleus
4.
what is flowing in electricity
Protons
1.
positively charged
2.
2000 X’s larger than e-‘s
3.
located in center or nucleus
Neutrons
1.
neutrally charged
2.
largest of atom particles
3.
located in nucleus
4.
by itself , unstable particle
Protons and electrons balance each other .
Organization of atoms
A.
III.
Electrons
Atomic number- # of protons in an atom
1.
Hydrogen—Atomic # =1, or 1 proton
2.
Carbon—Atomic # 6, or _______ protons
B.
Mass Number = protons + neutrons in the nucleus
C.
Isotopes= atoms with same # of protons, but different # of neutrons
D.
Element- collection of atoms w/ same # of protons
E.
Ion-a negatively or positively charged atom
F.
Periodic Table of Elements
1.
organized by atomic # in order & similar properties
2.
English or Latin name abbreviated by letter(s)
Atomic Models
A.
B.
Quantum Mechanical Model—
1.
accepted today
2.
complex
3.
electrons constantly moving in unique shaped orbitals
Bohr Model
1.
created by Niels Bohr in 1913
2.
Nucleus compact, circular orbits for e’s
3.
Each orbit = energy level = electron shell
4.
Bohr Orbit
Electron capacity
1
2
2
8
18
3
IV.
Strong Force
A.
B.
V.
Nuclear Force—
1.
attraction btwn protons and neutrons
2.
overcomes repulsion of positive charges
3.
exchange of pions
a.
tiny particles exchanged by protons and neutrons
b.
short lived
c.
short distance
Quarks
1.
smaller particles in neutrons and protons
2.
exchange gluons
Radioactivity
A.
B.
Radioactivity
1.
release of high energy particles by radioactive elements
2.
unstable nuclei , cuz imbalance of # protons to # neutrons
3.
a part of electroweak force
4.
radioactive isotopes- an atom w/ unstable nucleus
Radioactive decay
1.
breakdown of unstable atomic nucleus to become stable
2.
Beta
a.
beta decay
1.
a neutron changes into a proton and electron in the nucleus
2.
nucleus gains extra proton
3.
ejects electron = beta particle
4.
daughter product w/ higher atomic # or higher # protons
b.
dangers—beta particles are small and penetrate up to 1-2 cms of HO or flesh
c.
shield by Aluminum
+
3.
Alpha
a.
4.
5.
alpha decay- radioactive isotope ejects alpha particles
1.
alpha particles= nucleus of 2 protons & 2 neutrons (Helium nucleus)
2.
daughter product w/ 2 less neutrons & 2 less protons
b.
dangers—large alpha particles lose energy and only penetrate 1st layer skin
c.
shield by paper
a.
gamma decay- radioactive isotope emits gamma ray to gain stability
Gamma
1.
gamma ray-high energy photon
2.
daughter product = same # protons, neutrons
b.
dangers- strong radiation and penetrates thru living tissue
c.
shield by thick lead or other dense material
a.
half life—time it takes for ½ of the radioactive isotope to decay
b.
even though never hits 0, assume 0 after few half lives
c.
sample drops so quickly
Rate of decay