Big Bang and MO

Question 1

How did the Big Bang go ?

Answer 1

1. singularity
2. quarks and e-
3. protons and neutrons
4. really hot so only He+, Li+, H+, etc.
5. temp dropped
6. matter clumped
7. fusion: H burning made He
   He then burned and
   made C

Question 2

What is the Doppler effect ?

Answer 2

why sounds sound lower pitched as it moves away and high-pitched when closer

• think of an ambulance

Question 3

What is redshift ?

Answer 3

everything in the universe is moving away from us w/ increasing speed

Question 4

Does the element undergoing a reaction change ?

Answer 4

NEVER

Question 5

Difference b/w chemical reactions and nuclear reactions ?

Answer 5

• chemical: involve e-; element NEVER changes
• nuclear: involves nucleus, element DOES change

Question 6

What is fusion ?

Answer 6

adding 2 nuclei together

Question 7

What is fission ?

Answer 7

breaking apart 2 nuclei

Question 8

What is the requirement for fusion ? example ?

Answer 8

• high temp
• ex: stars !!

Question 9

What is affecting 2 nuclei that are moving toward e/a but are still separated by distances greater than the size of a nucleus ? What is needed ?

Answer 9

• Electrostatic force
• needs kinetic energy

Question 10

Why not use fusion reactors ?

Answer 10

Takes more energy than it produces

Question 11

Why is fission a chain reaction ?

Answer 11

As the nucleus splits, it releases n that hit other atoms nearby and induce 3 more fissions, then those 9….etc.

Question 12

What is critical mass ?

Answer 12

The mass required for the chain reaction to keep happening on its own.

Question 13

What are the 5 types of radioactivity ?

Answer 13

1. alpha particle emission
2. beta particle emission
3. positron emission
4. e- capture
5. gamma decay (electromagnetic radiation)

Question 14

What are nanomaterials vs nanoparticles ?

Answer 14

• nanomaterials: how tightly packed atoms are
• nanoparticles: many biomolecules

Question 15

What are emergent properties and what causes them ?

Answer 15

When atoms interact to form larger molecules, they show new behaviors they didn’t show before

Question 16

What is happening in a covalent bond (what’s being attracted) ?

Answer 16

Valence e- of one atom are attracted to nucleus of another

Question 17

Do covalent bonds share electrons ?

Answer 17

NOOO

Question 18

What is the molecular orbital theory ?

Answer 18

atomic orbitals combine like waves:
1. destructively (antibonding orbitals)

2. constructively (bonding orbitals)

Question 19

Are anti-bonding orbitals in or out of phase ? higher or lower in energy ?

Answer 19

• OUT of phase
• higher in energy

Question 20

MO SCHEME ?:???? IDKKKK

Question 21

What is paramagnetic vs diamagnetic ?

Answer 21

• paramagnetic: 1+ unpaired e-
• diamagnetic: no unpaired e-

Question 22

As nuclei are very close together during fusion, why does potential energy decrease.

Answer 22

Because the dominant force if attractive