Quantum Mechanics

Question 1

For the energy of a photon equation ΔE= hƒ. What does the h and f stand for?

Answer 1

Question 2

What does the Bohr Theory of a hydrogen atom state?

Answer 2

The nucleus is surrounded by electrons in fixed orbits with distinct energy levels.

Question 3

[Mnemonic]

As electrons go from a lower energy level to a higher energy level, they get AHED.

(how to remember the characteristics of electrons that go from low energy level to high energy)

Answer 3

As electrons go from a lower energy level to a higher energy level, they get AHED.

Absorb light

Higher potential

Excited

Distant (from the nucleus)

Question 4

What does an absorption spectrum show?

Answer 4

Which wavelength light is absorbed.

(When an electron moves from a lower energy level to a higher energy level it absorbs light (absorption).

Question 5

What does emission line spectrum show?

Answer 5

Which wavelength light is emitted.

When an electron moves from a higher energy level to a lower energy level, it emits light (emission) and a photon.

Question 6

What does it mean when an electron is in its ground state?

Answer 6

The electron is in its lowest energy level and all subshells are filled.

Example: Be ⇒ 1s² 2s²

Question 7

What does it mean when an electron is in its excited state?

Answer 7

The electron absorbed energy and “jumped” to a higher energy level.

Ground: Be ⇒ 1s¹ 2s²

Excited: Be^- ⇒ 1s¹ 2s¹ 2p¹

Question 8

What does the Heisenberg Uncertainty Principle state?

Answer 8

It is impossible to know the positionANDmomentum of an electron at the same time.

Question 9

What does the Pauli Exclusion Principle state?

Answer 9

No two electrons in the same atom can have the same four quantum numbers.

Question 10

What are the names of the four quantum numbers?

Answer 10

1. principle
2. azimuthal
3. magnetic
4. spin

Question 11

What are possible values for the principle quantum number?

Answer 11

Any positive integer (0, 1, 2, 3, etc.)

(A large integer value for the principal quantum number indicates a large radius and high energy.)

Question 12

What are possible values for the azimuthal quantum number?

Answer 12

From 0 to (n–1).

Question 13

What are possible values for the magnetic quantum number?

Answer 13

From -ℓ to +ℓ, including 0.

Question 14

What are possible values for the spin q.n.?

Answer 14

Either -½ (↑) or +½ (↓)

Question 15

What does each quantum number designate (n, ℓ, m_ℓ and m_s)?

Answer 15

1. n: main energy level (shell)
2. ℓ: shape/number of subshells
3. m_ℓ: orbitals
4. m_s: spins

Question 16

What does the Aufbau Principle (AKA “building up principle”) state?

Answer 16

Electrons fill subshells from LOWEST energy to highest energy.

Question 17

What does the photoelectric effect show?

Answer 17

Metals emit electrons when light is shined upon them (photoelectrons).

Question 18

Which subshell will fill first, the 5d subshell or the 6s subshell?

Answer 18

REMEMBER the (n + l) rule!!!!!!!

The lower the sum of the values of (n + l), the lower the energy of the subshell. And if the (n + l) values are the same, the subshell with the lower n value has a lower energy and will fill first.

5d: 5 + 2 = 7 and 6s: 6 + 0 =6

Question 19

What is the electron configuration for Chromium (Cr) and Copper (Cu)?

Answer 19

Chromium (Cr): [Ar] 4s¹ 3d⁵

Copper (Cu): [Ar] 4s^{<strong>1</strong>} 3d¹⁰

These are two notable exceptions to electron configuration!!

Question 20

What is a paramagnetic atom? Diamagnetic atom?

Answer 20

• paramagnetic: atom with unpaired electrons, pulled towards a magnetic field
• diamagnetic: atom with paired electrons, NOT pulled towards a magnetic field.