Lesson 1

Question 1

What is the Bohr Model?

Answer 1

Electrons travel around the nucleus in specific energy levels.

Question 2

What happens when electrons are in their stationary state in the Bohr Model?

Answer 2

Atoms do not emit energy in their stationary state.

Question 3

How do electrons move to higher energy levels in the Bohr Model?

Answer 3

Electrons can be excited by absorbing a certain amount of energy and jumping to a higher energy level.

Question 4

What occurs when electrons drop back to their lower stationary state in the Bohr Model?

Answer 4

They release energy in the form of light (photon).

Question 5

Bohr’s main energy levels consists of:

Answer 5

scientists later found that Bohr’s main energy levels/shells consisted of subshells or sublevels

1st shell - 1 subshell

2nd shell - 2 subshells

3rd shell - 3 subshells

Question 6

What does the Quantum Mechanics Model describe?

Answer 6

The statistical probability of finding the electron in a region of space (orbital) in an atom.

Question 7

How do electrons move between different orbitals according to the Quantum Mechanics Model?

Answer 7

By absorbing or emitting a specific quanta of energy (energy is quantized).

Question 8

What does the Heisenberg uncertainty principle state about electrons?

Answer 8

It is impossible to simultaneously know the speed and exact location of an electron.

Question 9

Why do we rely on probability when dealing with electrons in the Quantum Mechanics Model?

Answer 9

Electrons are too small and too fast, making it impossible to precisely determine their speed and location.

Question 10

Quantum Numbers and Atomic Orbitals

Answer 10

There are various types of atomic orbitals. Each type of orbital has a set of 4 numbers called quantum numbers, which describe various properties of the orbital

Analogy –> Specify the “address” of each electron in an atom

Question 11

What are the quantum numbers?

Answer 11

4 Quantum Numbers describe the distribution and behaviour of electrons in orbitals

n - describes orbitals energy level and relative size

l - orbital shape

ml - orientation in space

ms - describes the spin of an electron in an orbital

Question 12

What does the Principal Quantum Number (n) indicate?

Answer 12

Energy level/shell and size of an orbital for each element

Question 13

What is the range of n in the Principal Quantum Number?

Answer 13

From 1 to ∞ (only positive integers)

Question 14

How does n affect the energy required to occupy the orbital?

Answer 14

Increases as n increases for a given atom

Question 15

What does n2 represent in relation to the Principal Quantum Number?

Answer 15

Number of orbitals in the energy level

Question 16

quantum number n and shells

Answer 16

All orbitals that have the same n are said to be in the same shell

Question 17

What is the secondary quantum number (l) also known as?

Answer 17

Azimuthal quantum number

Question 18

What does the secondary quantum number (l) determine?

Answer 18

Shape of the orbital

Question 19

What are the allowed values of l dependent on?

Answer 19

The value of n

Question 20

What is the range of allowed values for the secondary quantum number (l)?

Answer 20

From 0 to n - 1

Question 21

What does l = 0 correspond to in terms of orbital shape?

Answer 21

s orbital

Question 22

What does l = 1 correspond to in terms of orbital shape?

Answer 22

p orbital

Question 23

What does l = 2 correspond to in terms of orbital shape?

Answer 23

d orbital

Question 24

What does l = 3 correspond to in terms of orbital shape?

Answer 24

f orbital

Question 25

If n = 2, what are the possible values for l?

Answer 25

0 and 1

Question 26

L quantum vaue and the energy subshells

Answer 26

All the ‘l’ quantum values represent different subshells or sublevels within each principal energy level

Example:

when n= 2; there are 2 values for ‘l’ (0 and 1) indicating two subshells in the second energy level

Question 27

Saturn and the atom (A Cross Section of an Atom)

Answer 27

From a distance the rings look solid. When viewed more closely, we notice the rings are made of smaller rings.

We can think about the Bohr model of an atom - where the second ring is actually made of two smaller (closely together) rings; the third ring is made of three closely grouped rings, etc…

Question 28

What does the Magnetic Quantum Number (ml) determine?

Answer 28

Number of orbitals in a subshell

Question 29

How does the Magnetic Quantum Number (ml) relate to the orientation of an orbital in space?

Answer 29

Specifies the orientation in space of the orbital; different orientations have different energies

Question 30

What are the possible values of the Magnetic Quantum Number (ml)?

Answer 30

-l to +l; e.g., if l = 2, ml can be -2, -1, 0, 1, 2

Question 31

How many values of ml are there for any given value of l?

Answer 31

(2l + 1) values; ie. # of orbitals for the l value

Question 32

perpendicular axis and quantum number ml

Answer 32

Called px, py, pz (the 3d axis is x,y,z)

Question 33

Shells

Answer 33

The SHELL is the main energy level

the shell number is given by the principal quantum number, n

It also corresponds to the period number on the periodic table

Question 34

Subshells

Answer 34

The SUBSHELLS/SUBLEVELS are orbitals of different shapes and energies

as given by the secondary quantum number, l

most often referred to as s, p, d, f.

Question 35

Quantum Numbers Summary

Answer 35

Taken together the three quantum numbers specific the orbital the electron occupies. Namely:the energy of the orbital, the shape of the orbital, and the orientation of the orbital

writing 3 quantum numbers to indicate every possible orbital an electron can occupy is cumbersome; instead do we do the following:

retain the numeric value of the principal quantum number and we use a letter to indicate the secondary quantum number:

l = 0 🡺 s; l = 1🡺 p; l = 2 🡺 d; l = 3 🡺 f

When combined, they indicate a specific orbital e.g. 1s orbital; 2s orbital; 2p orbital

Question 36

Electron Probabilities and the 1s Orbital

Answer 36

The 1s orbital looks very much like a fuzzy ball, that is, the orbital has spherical symmetry (the probability of finding an electron is the same in every direction)

The electrons are more concentrated near the center

Question 37

The Three p Orbitals

Answer 37

There are 3 p orbital; each orbital is cylindrically symmetrical with respect to rotation around one of the 3 axes, x, y, or zEach ‘p’ orbital has two lobes of high probability density separated by a node (region of zero probability)

Electrons are not found in the middle (the node of the orbitals)

Question 38

s, p, and d-orbitals - how many electrons do they hold?

Answer 38

s orbitals: Hold 2 electrons (outer orbitals of Groups 1 and 2)

p orbitals: Each of 3 pairs of lobes holds 2 electrons = 6 electrons (outer orbitals of Groups 13 to 18)

d orbitals: Each of 5 sets of lobes holds 2 electrons= 10 electrons (found in elements with atomic no. of 21 and higher)

Question 39

4) Spin Quantum Number(ms)

Answer 39

The spin quantum number explains some of the finer features of atomic emission spectra

The spin refers to a magnetic field induced by the moving electric charge of the electron as it spins

An orbital can hold 2 electrons that spin in opposite directions

Only possible values = +1/2 and -1/2

(clockwise or counterclockwise)

*Only worry about up or down on tests!

Question 40

Pauli Exclusion Principle

Answer 40

No two electrons in an atom can have the same 4 quantum numbers.

Each electron has a unique “address”:

Principal # → Energy level

2. Secondary # → Sublevel s,p,d,f
3. Magnetic # → orbital
4. Spin # → electron spin

Question 41

photon

Answer 41

a particle representing a quantum of light or other electromagnetic radiation. A photon carries energy proportional to the radiation frequency but has zero rest mass