Transcript Physical Science 1 Chapter 18 – Properties of Atoms & the

Physical Science
Chapter 18 – Properties of
Atoms & the Periodic Table
The Elements: Forged in Stars
The Origin of the Elements
Chemical Symbols
• Abbreviations for chemicals
• Punctuation is KEY
–
–
–
–
Capital Letters
Subscript
Superscript
Spacing
• Elements
– ALWAYS Start with a capital letter
– Symbols can be 1,2 or 3 letters
– First letter is capitalized and 2nd &
3rd are lowercase
• Atom- smallest piece of matter
that has the properties of the
element
•
CO doesn’t equal Co
–
CO = Carbon monoxide
–
Co = Cobalt
Atomic number
Always the smaller of the 2 #
Always a whole # (no decimals)
= number p+
Atomic mass
Always the BIGGER of the 2 #
Usually a decimal
= # p+ & n
The subatomic particles
p+ = positive charge
n = no charge
e- = negative charge
nucleus
nucleus
cloud
Electrons have such a small mass compared to
protons and neutrons we say electrons have no
mass – but really they do.
p+ = 1 amu
amu – atomic mass unit
n = 1 amu
1/12 of a Carbon -12
e- = 0 amu
QUARKS
Murray Gell-Mann found the name "quark"
in the book "Finnegan's Wake" by James
Joyce. The line "Three quarks for Muster
Mark..." Gell-Mann received the 1969 Nobel
Prize for his work in classifying elementary
particles.
Quark
Symbol
Spin
Charge
Up
U
1/2
+2/3
Down
D
1/2
-1/3
Charm
C
1/2
+2/3
Strange
S
1/2
-1/3
Top
T
1/2
+2/3
Bottom
B
1/2
-1/3
Finding the Quark
Quarks: Inside the Atom
Fermilab – National Particle Accelerator Lab Chicago IL
To Find a Quark- accelerate charged particles to high speeds and
cause them to collide with protons, which breaks the proton apart
EXTRA CREDIT: Find out what a
neutrino is & why it’s important to SD
Can you figure out which cork
stands for which quark?
Atomic Models
Models- used to help you understand something too
large or too small to see
Democritus – indivisible atom 450 BC
Dalton- atoms are just spheres
John Thomson – Plum Pudding model 1904
Discovered the electron 1897 – cathode ray tubePlum Pudding model- atoms had small negatively
charged particles- electrons- embedded throughout a
positively charged sphereINCORRECT BECAUSE- electrons are in clouds
AROUND the nucleus, not within the nucleus.
Also- did not distinguish between protons and
neutrons.
Models of the Atom over time
Models of Atoms
Ernest Rutherford – Rutherford model 1911
-Gold Foil experiment – positive nucleus (protons)
-Almost all the mass of an atom was in the central
atomic nucleus surround by electrons. INCORRECT
BECAUSE- did not distinguish between protons and
neutrons.
Chadwick – discovered the neutron 1932
Niels Bohr – Bohr model 1913
- Electrons traveled in fixed orbits around the nucleus.
The nucleus contained protons and neutrons.
INCORRECT BECAUSE- electrons are not in fixed orbits
but in a region around the nucleus- just occur more
frequently in certain places.
Electron Cloud Model- Current
Model
• Electron cloud model
– Protons and Neutrons in the nucleus
– Electrons in an electron cloud- the area
around the nucleus of an atom where
electrons are most likely to be. Very large
compared to the nucleus