I. Briefly describe the three types of primary bonds. What category of materials
ID: 1024453 • Letter: I
Question
I. Briefly describe the three types of primary bonds. What category of materials is linked to each bond type? 2. Briefly describe the two types of secondary bonds. Are they stronger or weaker than primary bonds? 3. Point defects, line defects, and area defects are three types of defects in crystal structures. Some are more significant than others. Briefly describe each type of defect and explain its significance with respect to material properties. 4. Describe the eutectic reaction. Be sure to explain the significance of the eutectic composition and temperature. 5. The eutectoid reaction is an important component of the iron-carbon phase diagram. Explain how a eutectoid reaction is similar to a eutectic reaction. Wh at is the primary difference? am Scan a graded copy of your work for these problems for indusion in your course portfolio. 6 Based on the ct) and atomic paking faston in randou 6. Based on the figure below showing a unit cell for a BCC lattice structure, calculate the unit cell volume (in cubic meters) and atomic packing factor, assuming this unit cell contains atoms of tungsten. You should reference Table 3.1 in the readings from Materials Science and Engineering: An Introduction by Callister and Rethwisch for the atomic radius of tungsten. You may find the in-class examples as well as those from this text helpful.Explanation / Answer
Ans-1)
3 Types of primary bonds are as follwes. Each type is explaned in sections definition, ilustrative example and other information (if neede).
A) Covalent bond:
a) Definition: It's a chemical bond formed through sharing of electrons between bonded atom in such way that each one of the bonded atom attains it's octet or duplet electronic state.
b) Example : A bond between homodiatomic molecules like H2, F2, Cl2 etc is purely covalent.
In H-H, each H share 1 e (which is the only electron) and both H attain a stable duplet statee.
In F2 (again each F shares 1 e in it's valence shell and both F attaind octet state.
In some heterodiatomic molecules which differ in electronegativity very little also shows formation of covalent but polar bonds.
e.g. H-Cl, SiH4 etc.
c) Compounds with covalent or polar covalent bonds are less polar or almost non-polar.
B) Ionic bonds:
a) Definition: It's a bond formed through complete tratnsfer of electron(s) from valence sheell of one atom to valence shell of other atom through which both attains stable electronic state like duplet of octet.
b) Example: Formation of NaCl ionic compound.
Na (Z=11): [Ne] 3s1 and Cl(Z=17) : [Ne]3s2 3p5.
Na+ = [Ne] and Cl = [Ne] 3s2 3p6 i.e. = [Ar]
Through transfer of 1 e from 3s1 shell by Na to 3p5 shell of Cl, Na attains octet core like Ne and Cl attain core ike Ar noble gas.
Hence, Na - Cl is an ionic bond.
C) Co-ordinate Covalent bond:
a) Definition: Co-ordinate bond forms through transfer of pair of electron from one of the bonded atom to other.
b) Example: Formation of Ammonium ion (NH4+).
Lone pair of electron on N transfered from N to H+ (proton) and thus the formation of co-ordinate covalent bond.
Co-ordinate bond is represented by a single headed arrwo point toward electron pair acceeptor.
H3N: --------> H+. i.e. H4N+.
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