Download Chapter 3

Chapter 3
Atomic Structure
DEMOCRITUS
• Greek philosopher
• 470-380 BC
• Deduced the ‘atom’
– Greek for
• Everything in
universe is made of
Lavoisier
•
• Concluded a
chemical reaction
Proust
• Law of
• A given compound
always has the
same ratios of
elements
•
Dalton
• Atomic theory of
matter
•
Dalton’s Postulates
• Each element is
• All atoms of a given element are
Dalton’s Postulates
• Atoms are
• A given compound always
How did he know?
• Indirect evidence
• Observations on how things reacted
Scanning Tunneling
Microscope
• Atoms in Silicon
Structure
• Michael Faraday
• Proved atoms
contained
Ben Franklin
• Studied static
electricity
• Flew a kite in a
thunderstorm
• Don’t do this at
home
• Concluded 2
charges
Charges
•
•
•
•
•
Positive (+)
Negative (-)
Like charges
Opposite charges
Built up
• When the electrons jump to a door or
person…
Cathode Rays
• TV
• Electrons moving through a glass tube
with little pressure inside.
• J.J. Thompson
Atomic Structure Review
• Proton
–
• Neutron
–
• Electron
–
The Modern Day Atom
• Nucleus:
–
–
• Orbiting
Nucleus:
–
Atomic Numbers (Z)
• Equal to
• NEVER CHANGES
• Sum of
Mass Number (A)
Isotopes of the Elements
• Same
• Different number of
Isotopes
• Defined:
–
• Will have different mass
• C-12
• C-13
Average Atomic Mass
•
•
•
•
Ave Mass =
No
No
Only
Practice
• What is the average atomic mass of
the following element.
Isotope/mass
Q-54
Q-55
Q-53
Q-56
Abundance
43%
29%
17%
11%
Ions of the Elements
• Same number of
• Has lost or gained
–Contains
Practice
• How many electrons in