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Material Science 1 > Chapter 1- Chapter 3.5 Quiz 1 > Flashcards

Chapter 1- Chapter 3.5 Quiz 1 Flashcards

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1
Q

What is ductile ?

A

Ductile refer to materials ability to undergo significant deformation before rupture or fracture.

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2
Q

What is brittle ?

A

Brittle is material tendency to break or shatter with little deformation when subjected to stress.

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3
Q

What are metals ? Properties ?

A

Metal are composed of one or more metallic elements. Dense, stiff, strong and ductile. It is also good conductor of electricity and heat

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4
Q

What is an alloy ? Properties ?

A

Metal element matrix with few extra addition in low quantities. Designed to enhance properties of base metal such as strength, corrosion, conductivity or resistance

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5
Q

What is ceramic ? Properties ?

A

It is combination of metal and non-metal. Very hard, strong, abrasion resistant but brittle. Poor thermal conductor. Example would oxidizes, carbides, nitrides, brodies

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6
Q

What is polymer ? Properties ?

A

Include the familiar plastic and rubber materials. Many of them are organic compounds that are chemically based on carbon, hydrogen and other nonmetallic element. Low in density however degrade under UV.

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7
Q

What are composite? Properties ?

A

Combination of metal, ceramic and polymer. Used in material engineering and design to target certain specific properties. Goal is to incorporate best characteristics of both materials.

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8
Q

What is atom ?

A

Atom consist of small nucleus composed of protons and neutrons which is encircled by moving electrons.

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9
Q

What is atomic number ?

A

Atomic number is equal to number of protons in nucleus

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10
Q

What is neutral atom ?

A

When protons are equal to electrons.

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11
Q

When is element ions and name them?

A

Cations when protons are more than electrons (loses electrons ).

Anions when electrons are more than protons( gaining electrons ).

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12
Q

What’s an isotopes ?

A

Isotopes are different forms of same element that have same number of protons but different number of electrons in their atomic nuclei.

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13
Q

What’s an isotopes ?

A

Isotopes are different forms of same element that have same number of protons but different number of electrons in their atomic nuclei. This result in them having different atomic mass.

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14
Q

What is atomic weight ?

A

Atomic weight of an element corresponds to the weighted average of atomic masses of atoms naturally occurring isotopes.

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15
Q

What is unit of atomic weight ?

A

Atomic mass unit (amu).

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16
Q

What is formula for calculating atomic mass ?

A

Atomic mass = number of protons + neutrons.

Can rearrange the equation to find protons and neutrons however round up the atomic weight to nearest integer to do this calculations.

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17
Q

How many quantum numbers are there and what to they represent ?

A

4 atomic number used for size, shape , n which describes energy level “ size “, L which describes the shape of the orbital, Ml which describes the orientation of the orbital and Ms describes the intrinsic spin of the electron.

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18
Q

What is “n”?

A

It is principal quantum number that describes the shell or (energy level) in which electrons are located. It only takes in integer values. Sometimes these shells are designated by letters K,L,M,N,O and so on which corresponds to n=1,2,3,4…..

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19
Q

What is “L” ?

A

The azimuthal number L. It describes the subshell or shape of the orbital. The formula to calculate L =(n-1).
Value of L corresponds to specific orbital.

L=0= s orbital

L=1= p orbital

L=2 = d orbital

L=3= f orbital

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20
Q

What is Ml ?

A

Magnetic quantum number describes number of orbital for each subshell. It can take on integer values from -L < Ml < L.

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21
Q

How many orbital each s has and how many electrons it can have ?

A

S- orbital ( L =0 )
N number minimum of at least 1 because L = n-1 formula. After one all energy levels can have s orbital n=1,2,3,4.. . Number of orbital are described by the Ml number from -L< Ml< L. S has 1 orbitals due L =0.
Therefore, it can only have 2 electrons.

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22
Q

How many orbital does each p have and how many electrons it can have ?

A

P orbital ( L=1) it has minimum value of n =2 and can exist in all energy after n=2. Number of orbital are described by the Ml number from -L< Ml< L. P has 3 orbitals due L =1 which makes ml = -1,0,1
Therefore, it can only have 6 electrons.

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23
Q

How many orbital does each D have and how many electrons it can have ?

A

D orbital ( L=2) it has minimum value of n =3 and can exist in all energy after n=3. Number of orbital are described by the Ml number from -L< Ml< L. D has 5 orbitals due L =2 which makes ml = -2,-1,0,1,2
Therefore, it can only have 10 electrons.

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24
Q

How many orbital does each f have and how many electrons it can have ?

A

F orbital ( L=3) it has minimum value of n =4 and can exist in all energy after n=4. Number of orbital are described by the Ml number from -L< Ml< L. F has 7 orbitals due L =3 which makes ml = -3,-2,-1,0,1,2,3
Therefore, it can only have 14 electrons.

25
Q

What Ms and Pauli exclusion principle ?

A

Associated with each electron is a spin moment which must oriented up or down. Ms has only two values +1/2 and-1/2. Each electron state can hold no more than 2 electrons that’s why s has 2, p has 6, d has 10 and f has 14.

26
Q

What is ground state?

A

When all electrons occupy lowest possible energies in accord to foregoing restriction an atom is said to be in a ground state.

27
Q

What is electron configuration?

A

Arrangement of electrons in atoms electrons shell.

28
Q

What are valence electrons ?

A

Occupy the outer most shell.

29
Q

What is electropositive ?

A

Give up valance electrons to become positive.

30
Q

What is electronegative?

A

Accept electron and become negative.

31
Q

How does electronegativity increases from on periodic table?

A

It increases from moving left to right.

32
Q

What is most involved in bonding ?

A

Bonding between different elements involve moments of electrons. The most involved electrons are those in valance electrons. They are furthest away from the nucleus and are easiest to remove. However, we can remove inner shell electrons but this requires a lot of energy.

33
Q

What is consider a stable element ?

A

Elements that have full valance electron shell are stable.

34
Q

What is coordinate number ?

A

Number of adjacent atoms / ions that surround a reference atom/ ion.

35
Q

What is ionic bonding ?

A

Electrons are transferred from one element to another. Typically contains ion. It follows that for ionic materials to be stable, all positive ions must have as nearest neighbour negatively charged ions in 3d scheme and vice versa.

Metal like to give away electrons that’s why they form positive ions ( cations ).

Non-metal like to receive ions that’s why they form negative ions ( anions ).

36
Q

What is attractive bonding force ?

A

Attractive bonding forces are Columbic that is positive and negative ions, by virtue of their electric charge, attract one another.

37
Q

What is covalent bonding ?

A

Results from sharing of electrons between two adjacent atoms. Bond strength in a covalent bond is similar to the ionic bond, but a covalent bond is directional which means it has shape.

Two types of covalent bonds nonpolar; equal sharing of electrons and polar: non-equal sharing of electrons. Need to calculate electronegativity if greater or equal to 0.5 polar covalent bonds and if less than 0.5 non-polar. The bond is between nonmetal and nonmetal.

38
Q

What is metallic bonding ?

A

Metal bonding occurs between metal and metal. Results from movement of electrons throughout material. Metallic bond is sharing electrons but is non-directional. In metallic bonding they share see or cloud of electrons which are free to move. Electrons a de-localised. Responsible for many properties of metals such as conductivity, meltability, lustre and ductility.

39
Q

What is secondary bonding ?

A

In this case electrons are not shared or transferred. This type of bond is formed when two atoms are brought very close proximity. This causes the electrons to NOT be uniformly disposed. The asymmetry of charge distribution causes the formation of attractive or repulsive dipole or bonding.

It arises from atomic or molecular dipole. The bonding results from Columbic attraction between positive end of one dipole and negative region of another.

40
Q

Type of metal structure ?

A

Crystalline, polycrystalline, amorphous ( ranked from least random to most)

41
Q

What is crystalline ?

A

Ordered structure that is described by repetitive volume called unit cell. It must have a fundamental unit cell which is repeated in 3 different directions throughout materials.

42
Q

What is unit cell ?

A

Smallest repetitive pattern volume which contains the complete lattice pattern of a crystal.

It is a basic building block of crystal. Chosen to represent symmetry of the crystal structure. Different crystal have unique shape and size of unit cell.

43
Q

What is lattice ?

A

3D array of points coinciding with atom position

44
Q

What are common crystal structure in metal?

A

Face centred cubic, body centred cubic and hexagonal closed packed.

45
Q

How many types of unit cells are there?

A

7 type.

46
Q

What is simplest cubic structure ?

A

BCC body centred cubic.

47
Q

Where can unit cell be placed ?

A

A corner of unit cell can be placed in between atoms, but typically, it is placed at the centred of atom.

48
Q

How many corner atoms are in 2d and 3d

A

4 in 2d there is 1 atom per unit cell and in 3d 8 corner atoms are shared by unit cell.

49
Q

Body Centred Cubic

A

Cubic unit cell located at 8 corner and a single atom in middle. There are 2 atoms per BCC crystal structure
1 interior atom + 8*1/8 corner atoms =2.

Coordination number of 8

Unit cell edge length = a= 4R/sqrt(3)

The crystal structure is relatively open, it’s not at lowest energy and may be unstable

50
Q

Face Centred Cubic

A

8 Atoms located at each corner, 6 at each face of cube and no interior atoms 8 atoms are shared by 8 units cell and 6 atoms are shared by 2 adjacent unit cells

Total number of atoms = 81/8+ 61/2=1+3=4

FCC has total 4 atoms

FCC coordination number is 12

Unit cell edge length = a=2R/sqrt(2)

51
Q

The hexagonal closed packed

A

Has a hexagonal unit cell it’s is a common non cubic crystal lattice, wheee planes with hexagonal are stacked on top of each other.

Has two lattice parameter a = length of hexagonal side, c= length of crystal Side

It has 12 corner atoms shared by 6 units cell so total contribution from corner 12*1/6 =2

2 face centred atoms shared by 2 unit cell 2*1/2 =1

3 interior atoms

3+1+2=6 total atoms

It has same CN as FCC which is 12

52
Q

How to compute density ?

A

P= nA/VcNa

n= number of atoms in unit cell
A= atomic weight
Vc= volume of unit cell
Na= avagardos number

53
Q

What does Bohr diagram attempt to in atom diagram ?

A

The Bohr diagram attempts to consider the spacing of electrons in an atom, as well as the energy at each position.

54
Q

Why do we have quantum numbers?

A

To distinguish between different atoms we need quantum numbers. We need to know where electrons as this determine bonding between atoms.

55
Q

When’s atom symmetrical and when’s it deformed ?

A

Symmetrical when atom is neutral

Deformed when magnetic or electric field is applied

56
Q

What influence the chemical behaviour?

A

The bonding and arrangement of atoms influences the chemical behaviours of materials.

57
Q

What is maximum coordination number and when is it possible ?

A

CN=12 only possible when R=r and when atoms are arranged in 3d

58
Q

Is melting point and boiling point indicator of bond force (T/F)

A

True

59
Q

What is bonding force ?

A

The bonding force is equilibrium between the coulomb force of attraction ( + nucleus - electron cloud ) and the force of repulsion between 2 electron cloud of elements.

Material Science 1 (10 decks)

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