indivisible identical react in fixed ratios + development of atomic models + stuff – electrons...
TRANSCRIPT
• Indivisible• Identical• React in
fixed ratios+
Development of Atomic Models
• + stuff• – electrons
• empty space
Rutherford’s Model:
Development of Atomic Models
couldn’t explain some properties like light colors.
prism
helium (He)lamp
prism
white light continuous spectrum
elements discrete lines of E & f
Atomic Emission Spectra
(only specific colors of energy & frequency)
Demo
H
Ne
He
Ar
One element at a time, let’s energize it and view the AES emitted.
A mystery for Niels Bohr.
Hydrogen Emission Spectrum
quantized into specific multiples
ofwavelengths,
electrons occupy only specific levels (or shells)of “quantized” energy(& wavelength & frequency)
Electrons as Waves
but none in between.
(1913–Niels Bohr)Bohr’s Shell Model
Bohr’s Shell Modele–’s emit (–) energy, move back to inner levels(n=5 to n=2)
e–’s absorb (+) energy, move to outer
levels(n=2 to n=5)
EXCITED state
GROUNDstate
∆E
5
242
Which transition shows a light wave of the greatest energy?
32
n=5 to n=2
Development of Atomic Models
1. Rutherford's model of the atom could NOT explain…
A. any properties of elements.
B. the chemical properties of elements.
C. the distribution of mass in an atom.
D. the distribution of positive and negative charges in an atom.
Quick Quiz!
2. Bohr's model of the atom proposed that electrons are found…
A. embedded in a sphere of positive charge.
B. in fixed positions surrounding the nucleus.
C. in fixed orbits of specific energy.
D. orbiting the nucleus in a single fixed circular path.
Quick Quiz.
3. The lines in the emission spectrum for an element are caused by…
A. the movement of electrons from lower up to higher energy levels.
B. the movement of electrons from higher down to lower energy levels.
C. the electrons in energy levels in the ground state.
D. the electron locations of an atom.
Quick Quiz.
4. Which transition in an excited hydrogen atom will emit the lowest energy of
light?
A. n2 to n4
B. n4 to n1
C. n3 to n2
D. n3 to n4
Quick Quiz.
longest wavelength
n isenergy level