Download Electrons in Atoms

Topic: Electrons in Atoms
Ground/Excited States
Do Now: List the charge, number of
protons, and number of electrons for:
p+ = 20
e- = 20-2=18
1. Ca+2 Charge = +
+ = 26
- = 26-3=23
+3
Charge
=
+3
p
e
2. Fe
Charge = -1
p+ = 9
e- = 9+1 =10
3. F-1
Charge = -3
p+ = 15
e- = 15+3=18
4. P-3
energy levels get closer
together the farther away
they are from nucleus
Larger orbits can hold more electrons
Potential Energy
energy levels get closer
together the farther away they
are from nucleus
Larger orbits can hold
more electrons
More PE = Less stable
Bohr Model
• Energy absorbed when
electron:
– moves to higher orbit
(farther from nucleus)
• Energy released when
electron:
– drops to lower orbit
(closer to nucleus)
Ground State vs. Excited State
• Ground state:
– Lowest energy state of atom
– electrons in lowest possible energy levels
• Configurations in Reference Tables are ground state
• Excited state:
– Many possible excited states for each atom
– One or more electrons excited to higher energy
level
Ground State
Excited State
• 2-8-8
• 2-8-7-1
• Total electrons =
• Total electrons =
– 2+8+8=18
– 2+8+7+1=18
• So protons = 18
• So protons = 18
• So atomic # = 18
• So atomic # = 18
• ELEMENT IS Ar
• ELEMENT IS Ar
8e-
1e-
8e-
7e8e-
2e-
2ep+=18
n0=22
p+=18
n0=22
Hydrogen jumps!
Bright Line Spectrum
– Electrons absorb energy (EXCITED) and
“jump” to a higher energy level
– After a short time, they “fall” back to
lower energy level, giving off a specific
amount of energy in the form of a photon
(light)
Scientists of the 19th century quickly
figured out that each element generates
its own unique set of wavelengths of
emissions and absorptions.
Hydrogen:
Neon line spectra