Ch02 Notes
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Transcript of Ch02 Notes
8/19/2015
1
Atom Diameter 10‐10 m = 0.1 nm
Nucleus Diameter 10‐14 m = 0.01 pm
Proton Mass 1.673x10‐24 g
Proton Charge 1.602 x 10‐19 C
Neutron Mass 1.675x10‐24 g
Electron Mass 9.109x10‐28 g
Electron Charge ‐1.602x10‐19 C
Size of the atom
Periodic Table
14C
Avogadro’s Number
Number of atoms required to create a mass in grams numerically equal to the atomic mass in amu
= 6.022x1023
A mole (or gram‐mole) is the amount of a substance that has Avogadro's number of atoms
One gramMole ofCarbon
12 grams of Carbon (0.42 Oz)
6.022 x 1023
Carbon atoms
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Steel Example Problem
Stainless Steel Recipe
Element Weight Percent Atomic Percent
Nickle 7%
Chromium 17%
Silicon 1%
Sulfur 0.03%
Manganese 2%
Carbon 0.15%
Phosphorous 0.045%
Iron 72.775%
Total
Model 1,000,000 atoms = how many grams of stainless steel?
Approximately = 1 gram
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ME 34400 Lecture 2Electron Energy
Niel Bohr’s Model Energy during transition
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Quantum Physics
Quantum Physics
Schrodinger Wave
Schrodinger Wave Equation 4 Quantum Numbers describe an electron orbital defined by wave equations
n = principle quantum number
L = Subsidiary quantum number
mL = Magnetic quantum number
ms = Electron spin
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Orbital Shapes Pauli Exclusion Principle
No two electrons in the same atom can have identical values for all four of their quantum numbers
n l ml # Orbitals Name # electrons1 0 0 1 1s 22 0 0 1 2s 2
1 ‐1, 0, +1 3 2p 63 0 0 1 3s 2
1 ‐1, 0, +1 3 3p 62 ‐2, ‐1, 0, +1, +2 5 3d 10
4 0 0 1 4s 21 ‐1, 0, +1 3 4p 62 ‐2, ‐1, 0, +1, +2 5 4d 103 ‐3, ‐2, ‐1, 0, +1, +2, +3 7 4f 14
He, Ne, Ar, Kr, Xe, Rn
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Electron Structure and Chemical Activity (Cont..)
• Electronegative elements accept electrons and become anions. [groups 6A & 7A]
• Some elements behave as both electronegative and electropositive. [group 4A to 7A]
Chart of Electronegativity
Remember, ranges from: 0 – 4.1
Bonds
• Ionic
• Covalent
• Metallic
Permanent Dipole Bonds
Fluctuating Dipole Bonds
Ionic Force for Ion Pair
• Nucleus of one ion attracts electron of another ion.
• The electron clouds of ion repulse each other when they are sufficiently close.
Force versus separationDistance for a pair of oppositely charged ions
Figure 2.11
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Ionic Force Sizes of atoms and ions
Figure 2.6
Bonding Energy Lattice Energy
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Covalent Bonds
Metallic Bonds
Na Mg
Permanent Dipoles
SymmetricalArrangement Of 4 C‐H bonds
CH4
No Dipolemoment
CH3ClAsymmetricalTetrahedralarrangement
CreatesDipole
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Why does methane (CH4) melt at ‐183 C and water (H20) melt at 0 C?