Transcript Atomic weight

디자인과 재료 문제풀이
김석범
MSM Lab . ( Graduate Student )
2014. 9. 23
Problem 2.1
Cite the difference between atomic mass and atomic weight
Atomic mass ?
Atomic weight ?
Atomic weight = Average of each atomic mass
2
Problem 2.4
(1) Cite two important quantum-mechanical concepts associated
with the Bohr model of the atom.
- electrons are particles moving in discrete orbitals
- electron energy is quantized into shells
3
Problem 2.4
(2) Cite two important additional refinements that resulted from the
wave-mechanical atomic
- electron position is described in terms of a probability distribution
- electron energy is quantized into both shells and subshells
- each electron is characterized by four quantum numbers (s,p,d,f)
4
Problem 2.4 sub
(3) Why we use “Orbital” method?
- Position
- Momentum
Uncertainty Principle
Heisenberg
5
Problem 2.13
Calculate the force of attraction between a K+ and an O2- ion the
centers of which are separated by a distance of 1.5nm
= 2.05*10-10N
6
Problem 2.13 Preview
7
Problem 2.13 Preview
8
Problem 2.13 Preview
9
Problem 2.19
Compute the percent ionic character of the inter-atomic bonds for
CsCl
For TiO2?
AX2 Crystal Structures
10
Problem 3 sub
Why BCC , FCC , HCP are important?
11
Problem 3 sub
Why BCC , FCC , HCP are important?
12
Problem 3.3
Show for the BCC crystal structure that the unit cell edge length a
and the atomic radius R are related through
13
Problem 3.9
Calculate the radius of an iridium atom, given that Ir has an FCC
crystal structure, a density of 22.4 g/cm3, and an atomic weight of
50.9g/mol
14
Problem 3.28
Compute the atomic packing factor for cesium chloride using the
ionic radii in Table 3.4 and assuming that the ions touch along the
cube diagonals.
rCs +
rCl-
=
0.170
= 0.939
0.181
 Since 0.732 < 0.939 < 1.0,
cubic sites preferred
So each Cs+ has 8 neighbor Cl-
15
Problem 3.28
Compute the atomic packing factor for cesium chloride using the
ionic radii in Table 3.4 and assuming that the ions touch along the
cube diagonals.
16
Problem 3.34
A hypothetical AX type of ceramic material is known to have a
density of 2.65g/cm3 and a unit cell of cubic symmetry with a cell
edge length of 0.43nm. The atomic weights of the A and X elements
are 86.6 and 40.3g/mol, respectively. On the basis of this information,
which of the following crystal structures is(are) possible for this
material: rock salt, cesium chloride, or zinc blende?
CsCl and ZnS
17