Physics fundamentals

Question 1

What are the 4 fundamental forces in the universe?

Answer 1

• The Strong force holds together the nucleus at the centre of atoms
• The Weak force also a nuclear force
• The Gravitational force due to mass
• The Electromagnetic force determines how atoms and molecules are held together

Question 2

What are photons?

Answer 2

carries the electro-magnetic force that holds atom together

The photon is a type of elementary particle, the quantum of the electromagnetic field including electromagnetic radiation such as light, and the force carrier for the electromagnetic force

Question 3

What should the quantum look like? (3)

Answer 3

• The electrons have wave-particle duality
• The electron wave has to be in a resonant orbit – that is there needs to be a half number of wavelengths that fit the orbit –there needs to be a standing wave
• The negatively charged electron is then in a bound state and does not crash into the positively charge nucleus

Question 4

Why does the electron not crash into the nucleus?

Answer 4

because it is in a bound state which is a resonance of the elctron wave

Question 5

What does n represent in quantum numbers?

Answer 5

principle quantum number

Question 6

What does l represent in quantum numbers?

Answer 6

angular momentum quantum number

Question 7

What does ml represent in quantum numbers?

Answer 7

magnetic quantum number

Question 8

What does ms represent in quantum numbers?

Answer 8

spin quantum number

Question 9

what is are the names of the subshells?

Answer 9

s, p, d, f

Question 10

What is the shape of an s orbital?

Answer 10

it is a spherically symmetric

Question 11

What shape is a p-orbital

Answer 11

not so symmetric and it “points” in different directions

Question 12

What is the pauli exclusion principle?

Answer 12

It is impossible for two electrons of a poly-electron atom to reside in the same orbital, unless the electrons have opposite spins.
It explains how elements have different chemical properties

Question 13

What is r₀ (seperation) equal to the sum of….

Answer 13

sum of both the attractive forces and the repulsive forces equals zero

Question 14

In a graph what gives the potential energy of the system at any seperation, r.

Answer 14

The area under the force (of attraction) graph

Question 15

How does a graph show the thermal expansion coefficient of a material?

Answer 15

shape of its E0 vs r0 curve

Question 16

How does a graph show the stiffness of a material?

Answer 16

Stiffness (elastic modulus) of a material is dependent on the shape of its force vs interatomic separation curve

Question 17

What is sp³ hybrid bonding?

Answer 17

tetrahedral molecule

Question 18

What is sp² bonding?

Answer 18

The carbon atoms bond in a hexagonal arrangement with sp2 hybrid bonds.
This is also known a benzene ring