Lectures 1-4

Question 1

The closer the electrons are to the nucleus, do they need more or less energy to leave the atom?

Answer 1

More energy they require to leave the atom

Question 2

What is the first electron shell represent with?

Answer 2

1s

Question 3

What is the second electron shell represented with?

Answer 3

2s, 2p

Question 4

What is the third electron shell represented with?

Answer 4

3s, 3p …

Question 5

What does the number to the power of the letter (s,p…) represent?

Answer 5

The number of electrons in that specific shell

Question 6

Valency is?

Answer 6

the atoms ability to enter a combination with other elements. Also the number of electrons that the element gains/loses to get a full outer shell

Question 7

Electropositive is?

What do they prefer to do?

Answer 7

Elements to the left of the period table.

Lose electrons

Question 8

Electronegative is?

What do they prefer to do?

Answer 8

Elements to the right of the period table

Question 9

Primary bonds

What happens to the electrons?

Answer 9

Strong chemical bonds

Shared or transferred

Question 10

Secondary bonds

What happens to the electrons?

Answer 10

Weak interactions between atoms and/or molecules

Question 11

Examples of primary bonding

Answer 11

Ionic, covalent, metallic

Question 12

Examples of secondary bonding

Answer 12

Van der waals, hydrogen bonding

Question 13

Ionic bonds are formed by…

Answer 13

electrons are transferred

Question 14

Covalent bonds are formed by…

Answer 14

electrons being shared

Question 15

Pros of metallic bonding

Answer 15

electrical conductivity, good tensile and compressive strength, high ductility

Question 16

Van der waals forces, where do these occur?

Answer 16

Between atoms or molecules

Question 17

What is the strength of van der waals forces?

Answer 17

Weak

Question 18

What happens when an induced dipole is formed?

Answer 18

As two atoms get close to each other, the negative electrons and the positive nuclei are attracted to eachother, bringing the atoms together with a very small force.

Question 19

Hydrogen bonding takes place where?

Answer 19

Between molecules that have H-F, H-N, and H-O bonds within them

Question 20

In a potential energy and internuclear separation graph, what can we say if the curve is deeper?

Answer 20

More potential energy to break the bonds, bond is stronger

Question 21

Coefficient of thermal expansion is?

Answer 21

How tolerant a material is towards heat

Question 22

What do systems generally prefer to reach?

Answer 22

A minimum energy state or lower enthalpy

Question 23

Crystalline structures are

Answer 23

atoms/molecules in a regular repeated form, usually solid

Question 24

Examples of crystalline structures at room temp

Answer 24

metals and ceramics

Question 25

Amorphous structures are

Answer 25

atoms/molecules in an irregular arrangement

Question 26

Single crystal material is…

Answer 26

whole material has a consistent arrangement of atoms

Question 27

Semi-crystalline material is…

Answer 27

crystalline regions and amorphous regions

Question 28

Polycrystalline material is…

Answer 28

composed of many single crystal regions or grains that are oriented at random

Question 29

Polymorphic materials can adopt more than one what?

Answer 29

More than one crystal structure

Question 30

Allotropic structures are…

Answer 30

pure elements that can adopt different crysal structure depending on the different temperatures and pressures

Question 31

Examples of crystal structures

Answer 31

NaCl sodium chloride, graphite and diamond

Question 32

What does face centred cubic mean?

Answer 32

Circle faces showing on each side of the cube

Question 33

What does body centred cubic mean?

Answer 33

The central sphere is contained in the centre of the cube

Question 34

What does a hexagonal close packed structure look like?

Answer 34

Two hexagons forming a prism, with three additional atoms at equidistance from every atom forming a triangle

Question 35

Vacancy in a material is

Answer 35

hole in the crystal of a material, absence of an atom

Question 36

Dislocation in a material is

Answer 36

defects when half a row of atoms are missing from the crystalline layer and the surrounding layers of the crystal close in.

Question 37

What is the pro to vacancy

Answer 37

Enable relative easy diffusion of atoms through a solid lattice

Question 38

Yield stress is

Answer 38

the maximum amount of force a material can take before it is inelastically deformed

Question 39

Tensile load is

Answer 39

force putting a material under tension

Question 40

Shear stress is

Answer 40

forces being applied which slide the layers in a crystal along side eachother

Question 41

Plastic deformation is when

Answer 41

the material becomes permanently deformed

Question 42

Edge dislocation slip is when

Answer 42

a shear stress is applied to a structure with a dislocation and then the atoms below the dislocation break their bonds and slide along. Until the dislocation is then at one end of the crystal structure.

Question 43

Dislocations in a material allow it to be

Answer 43

ductile

Question 44

The presence of dislocations in a material allow the planes of atoms to…

Answer 44

slip past eachother at lower applied stresses

Question 45

Ionic and covalent bonds are more what compared to metals

Answer 45

Brittle/less ductile

Question 46

Slip is usually easier in the direction of the atoms where they are…

Answer 46

more closely packed