Download (8th) Chapter 4-1 Cornell Notes Key Questions How did atomic

(8th) Chapter 4-1 Cornell Notes
• “Introduction to Atoms”
(8th) Chapter 4-1 Cornell Notes
• Key Questions
• How did atomic theory develop and change?
• What is the modern model of the atom?
(8th) Chapter 4-1 Cornell Notes
• Key Terms
(8th) Chapter
4-1 Cornell
Notes
Paragraph 1
• atom: smallest particle of matter;
• atomic theory grew from models.
(8th) Chapter 4-1 Cornell Notes
Paragraph 2
• John Dalton atom model, all alike and
different;
• 1897 J.J. Thomson: discovered electron;
• 1911 Ernest Rutherford: discovered nucleus,
and contained protons);
• 1913 Niels Bohr: described electrons having
E, moving in orbit around nucleus;
• electron movement depends on E level;
• later the neutron is added in the nucleus;
• Final model: nucleus has protons + neutrons,
surrounded by electron cloud.
(8th) Chapter 4-1 Cornell Notes
Paragraph 3
• protons, neutrons = in mass;
• electrons much smaller;
• but take up more space in atom than nucleus.
(8th) Chapter 4-1 Cornell Notes
Paragraph 4
atom of an element same
# of protons;
atomic number: # of
protons;
may have different # of
neutrons;
Isotopes: atoms w/ same
# protons, different #of
neutrons;
isotope identified by
“mass number”
mass number = #protons
+ # neutrons;
Note: isotopes have
different mass #s but
react same way
chemically.