Mats Lecture 5

Question 1

How is the number of protons represented?

Answer 1

Z

Question 2

What is the Atomic Mass Number?

Answer 2

A=N+Z
It is the total of neautrons and protons

Question 3

What are primary bonds?

Answer 3

Relatively Strong Bonds

Question 4

List the primary bonds

Answer 4

-Metallic Bonds
-Covalent Bonds
-Ionic Bonds

Question 5

What is a secondary bond?

Answer 5

Van Der Waals Bond

Question 6

How do metallic bonds work?

Answer 6

-Electropositive atoms donate their valence electrons to form a sea of electrons that are surrounding the atoms
-The positively charged ion cores are held together by mutual attraction to the electrons
-This results in strong metallic bonds

Question 7

How do metals specific bonding affect its properties?

Answer 7

-Their valence electrons are not fixed
-Under an applied voltage, the valance electrons move which causes a current (they are good conductors of electricity)
-Metallic bonds are non-directional resulting in good ductility
-Metals have high melting points

Question 8

What are covalent bonds?

Answer 8

The sharing of valence electrons among two or more atoms
-These bonds form specific angles for different materials

Question 9

What are properties of materials formed by covalent bonds?

Answer 9

-Covalent bonds are very strong which results in hard materials
-Solid materials exhibit very high melting points
-Have limited ductility because the bonds are directional
-Electrical conductivity is not high

Question 10

What are ionic bonds?

Answer 10

-When an atom donates a valance electron to a different atom, filling the outer energy shell of the second atom

Question 11

What happens to the atoms once an ionic bond is formed?

Answer 11

-The atoms gain an electrical charge once filling (or emptying) their outer shell

Question 12

What is the atom with a net positive charge called?

Answer 12

-Cation

Question 13

What is the atom with a net negative charge called?

Answer 13

Anion

Question 14

What are examples of materials with covalent bonds?

Answer 14

-Diamonds
-Sillicon Carbide
-Sillicon Nitride
-Boron Nitride

Question 15

What are Van Der Waals Bonds?

Answer 15

Molecules or atoms in which there is either an induced or permanent dipole moment attract eachother

Question 16

What is the definition of interatomic spacing?

Answer 16

How close two isolated entities are

Question 17

What does a force and interatomic graph tell us about the attractive force between two entities? Why?

Answer 17

-It increases significantly as the distance between the two entities decrease
-The electrons of the two entities is attracted to the protons of the other entity

Question 18

What does a force and interatomic graph tell us about the repulsive force between two entities? Why?

Answer 18

-It increases significantly as the distance between the two entities decrease
-The electron clouds of the two entities repel one another as they get closer

Question 19

What does a force and interatomic graph tell us about the net force on the graph?

Answer 19

-The point at which the graph is zero means that the net force is zero
-This is the point where the entities are balanced (equilibrium)

Question 20

What happens if you take the integral of the force and interatomic graph?

Answer 20

-You get the energy

Question 21

What happens in the energy and interatomic graph when the force and interatomic graph reaches the point at which it’s zero?

Answer 21

the force=0 is the low point in the energy graph
-The lowest energy is where the two entities are the most stable

Question 22

Why is the equilibrium bond energy (binding energy) important?

Answer 22

-It is the energy needed to create or break the bond
-This affects the melting point of the materials