MATS 321 Midterm 1
Which location is the tetrahedral interstitial sites for the BCC unit cell?
(1/2, 1, 3/4)
Which of the following defines a plane that is parallel to the z-axis?
(110)
What is the linear density of the <110> family of directions in the FCC crystal structure in terms of atomic radius, R?
1/(2R)
What is the planar density of the {100} family of planes in the FCC crystal structure in terms of atomic radius, R?
1/(4R^2)
How many electrons can occupy the d subshell (e.g., 4d)?
10
The coordination number for the BCC cell is equal to?
8
The stacking sequence of closed packed planes in FCC is:
ABCABC
Which of the materials below would have delocalized electrons?
Any metal, like Cu
Determine whether each of the following electron configurations is an inert gas, a halogen, an alkali metal, an alkaline earth metal, or a transition metal. Justify your choices: 1s2 2s2 2p6 3s2 3p6
Ar, Inert gas, completely filled shells
Covalent bonds are formed between:
Atoms with very similar electronegativities
Which atomic model assumes electrons move around the nucleus in discrete orbitals?
Bohr model
Which of the following are metals?
Cast iron, Brass
Determine whether each of the following electron configurations is an inert gas, a halogen, an alkali metal, an alkaline earth metal, or a transition metal. Justify your choices: 1s2 2s2 2p6 3s2 3p6 3d7 4s2
Co, Transition Metal, Partially filled "d" electron shell
Determine whether each of the following electron configurations is an inert gas, a halogen, an alkali metal, an alkaline earth metal, or a transition metal. Justify your choices: 1s2 2s2 2p5
F, Halogen, Has one electron deficit
What are possible interstitial sites for FCC and BCC unit cells?
FCC Tetrahedral (1/4, 3/4, 1/4), BCC Tetrahedral (1, 1/2, 1/4), FCC Octahedral (0, 1/2, 1) & (1/2, 1/2, 1/2), BCC Octahedral (1, 1/2, 1/4)
Most metals have lower density than polymer. T or F?
False
Which part of a FCC crystal structure is likely to chemically etch faster?
Grain boundary
Which choices are 0D or point defects?
Interstitial, Vacancy
What is the most likely dominant bonding mechanism for BaO solid compound?
Ionic
Determine whether each of the following electron configurations is an inert gas, a halogen, an alkali metal, an alkaline earth metal, or a transition metal. Justify your choices: 1s2 2s2 2p6 3s2 3p6 4s1
K, Alkali Metal, Has one excess electron
What is the most likely dominant bonding mechanism for Ni-Cr solid compound?
Metallic
Determine whether each of the following electron configurations is an inert gas, a halogen, an alkali metal, an alkaline earth metal, or a transition metal. Justify your choices: 1s2 2s2 2p6 3s2
Mg, Alkaline Earth Metal, Has two excess electrons
Which of the materials below would have delocalized electrons?
Ni
Which choices are correct explanations about the scanning electron microscope (SEM)?
Non-polished samples can be investigated using SEM. Useful resolution range for SEM is much wider than the optical microscopes. Samples for SEM need to be conductive or have conductive path/coating.
The coordination number is equal to:
Number of nearest neighbor atoms. 8 for BCC crystal structure
What are elements to consider with regard to the design, production, and utilization of materials?
Processing, structure, properties, and performance
Which of the defects listed is a 1D defect?
Screw Dislocation
What are examples for Advance Materials?
Semi-conductors, Nanomaterials, Biomaterials
What are the four Hume-Rothery Rules?
Similar atomic size (dR + or - 15%), Same crystal structure, Similar electronegativity, Similar valence
Determine whether each of the following electron configurations is an inert gas, a halogen, an alkali metal, an alkaline earth metal, or a transition metal. Justify your choices: 1s2 2s2 2p6 3s2 3p6 3d2 4s2
Ti, Transition metal, Partially filled "d" electron shell
Most metals have higher stiffness [elastic (or Young's) modulus] than polymers. T or F?
True
Features of scanning electron microscope:
Uses an electron beam that reflects back. Surface may or may not be polished or etched. Surface must be electrically conductive. Magnifications range from 10x to 50,000x. Very great depths of field.
Features of optical microscope:
Uses light microscope to study microstructure. Optical and illumination systems are its basic elements. Needs careful and meticulous surface preparations (ground and polished, etched)
Which of the following defines a direction along the x-axis?
[100]
In the FCC crystal structure, atoms touch along which direction?
[110]
In the BCC crystal structure, atoms touch along which direction?
[111]
Write an example of a valid set of quantum numbers for an electron in 3p state in terms of n, l, ml, and ms.
n = 3, l = 1, ml = +1, ms = + 1/2
What are examples of a valid set of quantum numbers for an electron state in 3d?
n = 3, l = 2, ml = 1, ms = +1/2. n = 3, l = 2, ml = -1, ms = +1/2.
