MAE 3324 CH2

Question 1

Why should you have a solid knowledge of interatomic bonding in solids?

Answer 1

In some instances, the type of bond allows us to explain the properties of a material.

Question 2

The atomic number is the number of…

Answer 2

Protons in the nucleus.

Question 3

Atoms are separated on the PT by?

Answer 3

Atomic number

Question 4

For an electrically neutral atom, what is the relationship between the atomic number and the number of electrons?

Answer 4

They’re the same number.

Question 5

Define “Atomic Mass.”

Answer 5

The sum of the masses of protons and neutrons within the nucleus.

Question 6

In an isotope, the number of _____ may vary.

Answer 6

Neutrons

Question 7

Define “Atomic weight.”

Answer 7

The weighted average of all the atomic masses of all the naturally occurring isotopes.

Question 8

Define 1 amu.

Answer 8

1/12 of the atomic mass of the most common isotope of carbon which is carbon 12.

Question 9

What is avagodros number?

Answer 9

The number of atoms in one mole of material. 6.022E23 atoms/mole
.

Question 10

Is amu/atom any different than grams/mole?

Answer 10

No, they’re the same thing.

Question 11

Define “Quantum mechanics.”

Answer 11

A set of principles and laws that govern systems of atomic and subatomic entities.

Question 12

What is mean by the saying “Electrons are quantized?”

Answer 12

They can only hold a certain amount of energy.

Question 13

During a quantum jump, when an electron absorbs energy, it transitions to a _____ energy state.

Answer 13

higher

Question 14

During a quantum jump, when an electron emits energy, it transitions to a _____ energy state.

Answer 14

lower

Question 15

In the wave mechanical model, an electron is considered to exhibit what two characteristics simultaneously?

Answer 15

The electron behaves as both a wave and a particle simultaneously.

Question 16

In the wave mechanical model, the position of the electron is described by what?

Answer 16

A probability distribution or “electron cloud.”

Question 17

Shells are specified by?

Answer 17

A principal quantum number n, which may take on integral values beginning with unity (one).

Question 18

How many electrons can fit in the 1s shell?

Answer 18

2

Question 19

How many electrons can fill the 2s shell?

Answer 19

2

Question 20

How many electrons can fill the 2p shell?

Answer 20

6

Question 21

How many electrons can fill the 3s shell?

Answer 21

2

Question 22

How many electrons can fill the 3p shell?

Answer 22

6

Question 23

How many electrons can fill the 3d shell?

Answer 23

10

Question 24

The first quantum number is related to what physical aspect of the atom?

Answer 24

The electrons average distance from the nucleus.

Question 25

What does the second quantum number designate?

Answer 25

The subshell.

Question 26

Name the values for the quantum number L and their subshell designations.

Answer 26

``` 0 = s 1 = p 2 = d 3 = f ```

Question 27

Electron orbital shapes depend on what quantum number?

Answer 27

L

Question 28

The s orbitals are in the shape of?

Answer 28

Spheres.

Question 29

The third quantum number stipulates what?

Answer 29

The number of electron orbitals for each subshell. Extra Notes: This value is also referred to as the magnetic number.

Question 30

The third quantum number is also called what?

Answer 30

The magnetic number.

Question 31

When L=0, m_L can only have a value of what? This corresponds to what subshell?

Answer 31

Zero. This corresponds to an S subshell with only one orbital.

Question 32

If L =1, what values can m_L take on, and what orbitals are possible?

Answer 32

M_L could be -1, 0, or 1 | Three p orbitals are possible (px, py, and pz).

Question 33

How many orbitals do "d" and "f" subshells have respectively?

Answer 33

5 and 7

Question 34

In the absence of an external magnetic field, all orbitals within each subshell are?

Answer 34

Identical in energy.

Question 35

What is the fourth quantum number and what values can it take on?

Answer 35

The spin moment (abbreviated as ms). Values can take: ms = +1/2 = spin up or ms = -1/2 = spin down

Question 36

T or F | The smaller the principal quantum number the lower the energy?

Answer 36

True

Question 37

Within each shell, the energy of a subshell level increases with the value of the __ quantum number.

Answer 37

L

Question 38

What is the "Pauli Exclusion Principle?"

Answer 38

A quantum-mechanical concept, which stipulates that each electron state can hold no more than two electrons that must have opposite spins.

Question 39

When all the electrons occupy the lowest possible energies in accord with the foregoing restrictions, an atom is said to be in its ______.

Answer 39

Ground State

Question 40

What does the electron configuration describe?

Answer 40

A model that represents the manner in which electron states are occupied. For example, the electron configuration of Helium is 1s^2.

Question 41

Valence Electrons are the electrons that

Answer 41

Occupy the outermost shell.

Question 42

Rows on the PT are called?

Answer 42

Periods

Question 43

As a general rule, electronegativity increases in moving from ___ and ___ on the PT.

Answer 43

Left to right and bottom to top.

Question 44

When atoms are brought together what two forces act?

Answer 44

Attractive and repulsive forces.

Question 45

The minimum in the net energy curve corresponds to what?

Answer 45

The Equilibrium spacing R_0

Question 46

The bonding energy corresponds to what on the Interatomic Separation vs Potential Energy Graph? What is the physical interpretation of this observation?

Answer 46

The minimum value on the curve. This value of energy represents the amount needed to separate the two atoms by an infinite distance.

Question 47

For large bonding energies, what four physical characteristics are usually present?

Answer 47

1. High melting points 2. Solid at room temp 3. High modulus of elasticity 4. Low coefficient of thermal expansion "Henry Sang High & Low"

Question 48

Low bonding energies usually result in what physical state?

Answer 48

Gaseous.

Question 49

T or F | Intermediate bonding energies usually result in liquids?

Answer 49

True

Question 50

The mechanical stiffness of a material is dependant upon? Explain why some materials are stiff while others are not with respect to the first question.

Answer 50

The shape of its interatomic spacing vs force curve. The slope for a relatively stiff material will be steep; slopes are shallower for more flexible materials.

Question 51

What are the three primary bonds in solids?

Answer 51

Ionic Covalent Metalic

Question 52

Ionic bonding is found between what types of elements?

Answer 52

Metals and non-metals.

Question 53

In ionic bonding which element gives up electrons?

Answer 53

The metals give up valence electrons to the non-metallic elements. Extra notes: In the process, the new molecule acquires a noble gas electron configuration and a net charge.

Question 54

Attractive forces in ionic bonding are ____.

Answer 54

Couloumbic

Question 55

Covalent Bonding is found between materials whose atoms have

Answer 55

Small differences in electronegativity. Extra notes: These atoms are close on the periodic table.

Question 56

In Covalent Bonding, electrons are ____.

Answer 56

Shared.

Question 57

T or F | Ionic bonding is directional?

Answer 57

False

Question 58

T or F | Covalent bonding is directional?

Answer 58

True

Question 59

T or F | Most materials that are covalently bonded are insulators or in some cases, semiconductors?

Answer 59

True

Question 60

What is bond hybridization?

Answer 60

The mixing (or combining) of two or more atomic orbitals with the result that more orbital overlap during bonding results. Commonly occurs in carbon and other non-metallic substances. Extra info: Directional in nature.

Question 61

Describe the motion of electrons in metallic bonding?

Answer 61

They're free to move between atoms that constitute the metal.

Question 62

T or F | The metallic bond is non-directional?

Answer 62

True

Question 63

Secondary Bonding (Van der Waal) forces result from what?

Answer 63

Molecular dipoles. Extra Notes: The bonding results from the coulombic attraction between the positive end of one dipole and the negative region of an adjacent one.

Question 64

With respect to secondary bonding, dipole interactions occur in what three scenarios?

Answer 64

1. Induced Dipoles 2. Induced dipoles and polar dipoles 3. Polar dipoles

Question 65

Hydrogen bonding is a type of ____.

Answer 65

Polar molecule bonding.

Question 66

Describe hydrogen bonding.

Answer 66

Hydrogen bonding occurs between molecules in which hydrogen is covalently bonded to Fluorine, Oxygen, or Nitrogen.

Question 67

In mixed bonding, the degree of either bond type depends on___.

Answer 67

The relative positions of the constituent atoms on the periodic table. Extra Notes: If the substance is primarily composed of materials that are close on the PT (similar electronegativities) the material will be covalent dominant. If the opposite is true the material will be ionic dominant.

Question 68

A crystal's structure is analogous to...

Answer 68

How atoms are arranged in a crystal.

Question 69

Atomic structure is analogous to...

Answer 69

How atoms are shaped or bonded.

Question 70

What is morphology?

Answer 70

The study of how a crystal is shaped (e.g. micro/macro-structure).

Question 71

In a neutral species, the number of protons equals the...

Answer 71

Number of electrons.

Question 72

Give the letter designation for the principle shells 1 to 4 in that order.

Answer 72

``` 1 = K 2 = L 3 = M 4 = N ``` Kangaroos Like Margarita Nights

Question 73

A smaller principal quantum number equates to a ____ energy level.

Answer 73

Lower.

Question 74

Within each shell, the energy of a subshell level increases with the value of the___.

Answer 74

l*QN

Question 75

T or F With respect to bonding forces, the difference between bond types depends on how electrons behave when two atoms are put near each other.

Answer 75

True

Question 76

T or F Materials with large bonding energies have: 1. Deep and Narrow Troughs on their graphs of interatomic spacing vs Force diagrams. 2. Low coefficients of thermal expansion.

Answer 76

True to both statements.

Question 77

T or F | In ionic bonding, the electronegative metals give up their valance electrons to the non-metallic electropositive atoms?

Answer 77

False. | The electropositive metals give up their electrons to the electronegative non-metals.

Question 78

T or F When ionic bonding is complete, materials tend to be non-conductors of electricity in crystalline form but will conduct in liquid form?

Answer 78

True

Question 79

T or F | Covalent bonds form between atoms that are close on the periodic table and have relatively similar electronegativities.

Answer 79

True

Question 80

T or F | Most covalently bonded materials are electrical insulators, and in some special cases are semiconductors.

Answer 80

True

Question 81

T or F | In metallic bonding, the bond is non-directional and atoms are shared as in covalent bonding.

Answer 81

True

Question 82

T or F | In secondary bonding forces, there is a transfer of electrons such as in ionic bonding?

Answer 82

False Atoms do not share electrons in secondary bonding. Rather, the sources of attraction between the two are couloubic in nature and results from dipole attraction.