The Model of the Atom II
The Atom
Review
• Dalton’s Atomic Theory
• All matter made up of atoms
• Atoms are indivisible
• Atoms of same element are exactly alike
Dalton Was Wrong—But Not His Fault
The Atom
Review
• Dalton’s Atomic Theory
• Atoms ARE made of smaller particles
• Neutrons
– Discovery of isotopes Carbon-12, Carbon-14
• Protons
– Rutherford’s Gold Foil experiment
• Electrons
– Thomson’s cathode ray experiment
The Atom
Electrons Most Important
• Why?
• Responsible for most chemical and physical
properties
• Responsible for chemical bonding
– Covalent (sharing) & Ionic (transferring)
• Understanding electron arrangement allows
for understanding of chemical reactions
Electromagnetic Spectrum (EMS)
• RMIVUXG= Ronald McDonald Is Very Ugly &
Xtremely Goofy.
•
•
•
•
Radio> Microwave> Infrared> Visible> UV> X ray> Gamma
Long >>> short wavelength
Low frequency >>> high frequency
Low energy >>> high energy
Electromagnetic Spectrum (EMS)
• Visible = ROYGBIV
• Red>Orange>Yellow>Green>Blue>Indigo>Violet
• Every element emits a different set of
wavelengths, we can thus ID an element by
its EMS.
The Atom
Energy Levels
• Discovered by observing emissions spectra
The Atom
Energy Sublevels
• Scientists Seeing Unexpected Results With
Emissions Spectra
• Hypothetical: only 3 energy levels, how
many possible colors could be seen?
3
2
1
3
The Atom
Energy Sublevels
• Scientists Seeing Unexpected Results With
Emissions Spectra
• They were seeing a lot more spectral lines
than what they expected
• Only explanation: sublevels
3
2
1
The Atom
Energy Sublevels
• How many colors would you expect to see
now?
3
19!!
2
1
The Atom
Energy Sublevels
• Given Abbreviations
• From lowest energy to highest energy:
– s, p, d, f
• Each energy level has a corresponding
number of sublevels
Energy Level 1
1 Sublevel , 1s
Energy Level 2
2 Sublevels, 2s,2p
Energy Level 3
3 Sublevels, 3s, 3p, 3d
Energy Level 4
4 Sublevels, 4s, 4p, 4d, 4f
The Atom
Energy Sublevels
• Each sublevel has a specific number of
orbitals:
s
p
d
f
2 (1 orbital)
6 (3 orbitals)
10 (5 orbitals)
14 (7 orbitals)
The Atom
Energy Sublevels
• Each orbital can hold only TWO electrons:
s
p
d
f
2 (1 orbital-2 total electrons)
6 (3 orbitals-6 total electrons)
10 (5 orbitals-10 total electrons)
14 (7 orbitals-14 total electrons)
The Atom
Energy Levels
• Each energy level then has a set number of
sublevels and maximum electrons:
1 – only s 2 electrons max
2- s and p sublevels, 8 electrons max
3- s, p, and d sublevels, 18 electrons max
4- s, p, d, and f sublevels, 32 electrons max
The Atom
Electron Orbitals
• Regions in space where electrons are likely to
be found
• Follows electron cloud model
– Electrons do not travel in a specific orbit
• Each orbital holds maximum of 2 electrons
• Electron configuration
– When all electrons are in most “comfortable”
orbital and energy level
The Atom
Orbital Shapes
The Atom
Electron Orbitals
• Snapshot Analogy
The Atom
Electron Orbitals
• Snapshot Analogy
The Atom
Electron Orbitals
• Snapshot Analogy
The Atom
Electron Orbitals
• Snapshot Analogy
The Atom
Electron Orbitals
• Snapshot Analogy
The Atom
Electron Orbitals
• Snapshot Analogy
The Atom
Electron Orbitals
• Snapshot Analogy
The Atom
Electron Orbitals
• Snapshot Analogy
The Atom
Electron Orbitals
• Snapshot Analogy
Orbital Shape
The Atom
Electron Configurations
• Rules to tell you in what order the orbitals get
filled
• Aufbau principle
• LOWEST energy orbitals get filled FIRST
• Pauli exclusion principle
• Each orbital can only hold TWO electrons—
each with opposite “spin”
• Hund’s Rule
• Each orbital must have ONE electron before
any has TWO
Electron Configurations
• Aufbau principle
• 1s gets filled before 2s, 2s before 2p etc. (see “arrow chart”)
• Pauli exclusion principle
• Boxes often represent orbitals
• Hund’s Rule
2s
2px
2py
2pz
Writing Electron Configurations
• The electron configuration for H is 1s1
• The e- configuration for He is 1s2
• Li = 1s22s1
• Na = 1s22s22p63s1
• Notice that the superscripts should add up to
the total number of electrons!
Sodium
1s
11 electrons
2s
2p
3s
3p
3d
4s
4p
4d
4f
5s
5p
5d
5f
6s
6p
6d
6f
7s
7p
1s22s22p63s1
Electron Configurations
EXCEPTIONS
• Some elements do NOT follow all the rules
• Copper
• Expected: Cu- 1s22s22p63s23p64s23d9
4s
3dxy
3dxz
3dyz
3dx2-y1
3dz2
Electron Configurations
EXCEPTIONS
• Some elements do NOT follow all the rules
• Copper
• Expected: Cu- 1s22s22p63s23p64s23d9
• Actual: Cu- 1s22s22p63s23p64s13d10
4s
3dxy
3dxz
3dyz
3dx2-y1
3dz2
Partially-filled 3d sublevel, with a filled 4s is less stable
than a filled 3d and a half-filled 4s
Kernel Structures
Electron Configurations
• Can get very long as you go down the PT
• Kernel structures are used as abbreviations
• The “kernel” is ALWAYS a Noble Gas
(group 18)
• They represent all inner electrons
Kernel Structures
Electron Configurations
Iodine
1s22s22p63s23p64s23d104p65s24d105p5
Tellurium
1s22s22p63s23p64s23d104p65s24d105p4
Antimony
1s22s22p63s23p64s23d104p65s24d105p3
Tin
1s22s22p63s23p64s23d104p65s24d105p2
Kernel Structures
Electron Configurations
Iodine
1s22s22p63s23p64s23d104p65s24d105p5
Find the noble gas that comes BEFORE the
element
Krypton
[Kr]5s24d105p5
The End