Structure and Properties of Matter Pt1

Question 1

Describe the characteristics and limitations of the

Nuclear Model of the Atom

2 points, 2 limitations

Answer 1

• mostly empty space
• e- are outside of a small positively charged nucleus
• limitations:
• nucleus cannot be only pos or it would break
• couldn’t acount for mass of the atom
• scientists thought e- countinuously gave off radiation and would eventually crash into the nucleus, but this doesn’t happen

Question 2

Describe the characteristics and limitations of the

Revised Nuclear Model

Answer 2

• discovered positive proton and neutral neutron

Question 3

Describe the characteristics and limitations of the

Bohr Model

2 poins, 3 limitations

Answer 3

• energy of e- is quantized (can only have specific values, can move within its energy lvl without losing energy)
• to move from one energy lvl to another, e- needs to gain or lose energy
• limitations:
• could only explain the line spectra for atoms with only one e-
• couldn’t explain why there are only “allowed” orbits/energy lvls
• couldn’t explain many physical or chemical properties

Question 4

Describe the characteristics and limitations of the

Quantum Mechanical Model

Answer 4

• ## e- cloud, density is proportional to the probability of finding an e- there

Question 5

How does this work

Emission Spectrum

Answer 5

• white light passes through hot gas and gets separated by a prism
• light is emitted when an e- goes to a lower energy lvl and releases energy

emission spectrum and absorption spectrum

Question 6

How does this work

Absorption Spectrum

Answer 6

• wihte light passes through cool gas, some wavelengths gets absorbed by the atoms, causing black lines in the absorption spectrum

Question 7

What is an

Orbital

Answer 7

• a 3D description of where an e- could be

Question 8

What are the

4 Quantum numbers and their symbols

Answer 8

• principle quantum number (n)
• secondary quantum number (l)
• magnetic quantum number (ml)
• spin quantum number (ms)

Question 9

Principle Quantum Number

3 points

Answer 9

• the main energy lvl occupied by the e-
• can be any pos integer from 1 to infinity
• max # of e- in an orbital is 2n squared
• e.g. if n=3; max # is 18

Question 10

Secondary Quantum Number

4 points

Answer 10

• describes shape of an orbital
• any integer from 0 to n-1 (e.g. if n=2, l=0, 1)
• l = 0, s (sphere)
• l = 1, p (dumbbell)
• l = 2, d
• l = 3, f
• each orbital holds max 2e-

Question 11

Magnetic Quantum Number

2 points

Answer 11

• describes orientation of orbitals around nucleus
• any integer from -l to +l (if l = 2, ml = -2, -1, 0, 1, 2)

Question 12

Spin Quantum Number

3 points

Answer 12

• specifies direction of the axis of the e-
• must have opposite spins or e- will repel e/o
• +1/2 or -1/2

Question 13

Pauli Exclusion Principle

Answer 13

• no 2 e- can have the same quantum numbers

Question 14

Aufbau Principle

Answer 14

• e- always fill lower energy orbitals before moving onto higher energy orbitals
• fill diagonally
  1s
  2s 2p
  3s 3p 3d
  4s 4p 4d 4f
  5s 5p 5d 5f

Question 15

Hund’s Rule

Answer 15

• when there are orbitals with the same energy in the same energy lvl, e- will half fill before pairing up
• up spin