1. Atomic Structure

Question 1

What is the mass of a:
proton =
neutron=
electron=

Answer 1

proton= 1AMU
neutron=1 AMU
electron= 1/2000 the mass of a proton

Question 2

What is the difference between:
Atomic Number
Mass number

Answer 2

Atomic Number- The number of protons given in the element ( this never changes).

Mass number- The sum of the element’s protons and neutrons. This can change if there are isotopes.

Question 3

What are valence electrons?

Answer 3

Electrons that are far from the nucleus . They are more likely to become involved in bonds with other atoms.

Question 4

What is an isotope?

Answer 4

same element with varying mass numbers.

Essentially, it has a different number of NEUTRONS.

Remember, the number of protons never changes.

Question 5

What is the atomic mass?

Answer 5

essentially equal to the mass number, the sum of an element’s protons and neutrons

Question 6

How is 1 AMU defined?

Answer 6

1/12th the mass of a carbon-12 atom.

Question 7

What are the isotopes of hydrogen? How many AMUs are they?

Answer 7

Protium= 1 proton and AMU=1 (no neutron)
Deuterium= 1 proton, 1 neutron (AMU=2)
Tritium= 1 proton, 2 neutrons (AMU=3)

Question 8

What is the atomic weight?

Answer 8

the weighted average of the naturally occurring isotopes of an element.

This is important to note because the periodic table lists the atomic weight (average) not the mass.

For example: if you have two isotopes for chlorine, chlorine 35 and chlorine 37, and there are three times more chlorine 35 than chlorine 37, than the atomic weight will be closer 35.

Question 9

What is Avogadro’s number?

Answer 9

6.022 x 10²³

The atomic weight = mass of one mole of an element

Question 10

What is Quantum?

Answer 10

The difference between energy levels of orbits.

Question 11

What is the Planck Relation and what does it describe?

Answer 11

Describes the energy of the quanta (energy between orbitals).
It is discrete, not continuous
It represents the energy of an emitted electron

E=hf Plank relation (frequency)

E= the energy of the quanta
h= the proportionality constant known as Planck’s constant= 6.626x10^-34
f= (sometimes V) the frequency of radiation

Question 12

What is the angular momentum of the electron and what does it represent?

Answer 12

if you increase the velocity, mass, or radius, or orbit, you increase the angular momentum.

n=orbit in which the electron is revolving
v= velocity

m=mass of the electron
r= radius of the nth orbit

Question 13

What is the energy of the electron equation?

Answer 13

e= energy of the electron
R_H= Rydberg Unit of Energy= 2.18 x 10^-18 J/Electron
n=orbit in which the electron is revolving

What’s important is that the distance it is removed from the nucleus will reduce the charge by the ^2 value of the distance.

Relationships: From this, we can see that really the only variable that changes is n, or the orbit. So the energy is directly proportional to the orbit of the electron. Additionally, it really is only going to change in discrete amounts, because orbits occur at discrete levels.

Question 14

How can you go from a lower energy level to higher energy level with electrons? (x4)

Answer 14

Absorb light
Higher potential energy
Excited State
Distant (from nucleus)

Question 15

What is ground state vs excited state?

Answer 15

Ground State: of an atom is the state of lowest energy, in which all electrons are in the lowest possible orbitals.

Excited State: when at least one electron has moved to a subshell of a higher than normal energy.

Question 16

What is the atomic absorption spectrum?

Answer 16

This is unique to each element. For an electron to jump from a lower energy level to a higher one, it must absorb an amount of energy precisely equal to the energy difference between the two levels.

These correspond exactly to the wavelengths of the emission.

You can use this to identify elements in the gas phase using absorption spectra.

Question 17

What is the atomic emission spectrum?

Answer 17

When electrons return from the excited state to the ground state, they emit an amount of energy that is exactly equal to the energy difference between the two levels, and each element has its unique level. Sometimes the electromagnetic energy corresponds to its visible light range

Question 18

What is the Electromagnetic Energy of Photons?

Answer 18

Electromagnetic Energy of Photons: these occur when an electron goes from a higher to lower state, and by doing so emits a photon. Each photon will have a characteristic wavelength of energy specific to the energy transition it undergoes.

Question 19

What is the equation for the energy of electron transition?

Answer 19

E= electromagnetic energy released by photon when electron drops from higher to lower state
Planck’s constant= 6.626x10-34 Jules x sec
C= speed of light in a vacuum (3.00 x 108 m/s)
λ= wavelength of the radiation

Question 20

What is the quantum mechanical model?

Answer 20

posits that electrons do not travel in defined orbits but rather are localized in orbitals

This is a more advanced understanding than the stand shell model (Bohr).

Question 21

What is the Heisenberg Uncertainty Principle?

Answer 21

It is impossible to simultaneously determine, with perfect accuracy, the momentum and the position of an electron

Question 22

What is an orbital?

Answer 22

Region of space around the nucleus defined by the probability of finding an electron in that region of space.

Question 23

What are the four quantum numbers?

Answer 23

n (Principal quantum number): describes the energy of the shell
Values: Can be any positive integer value. (essentially, each row is labeled 1-7)

l (azimuthal quantum number): Describes the subshells within a given energy level
subshells: s,p,d,f
* s= l=0
* p= l=1
* d= l=2
* f= l=3
* Mnemonic: Scott’s penis digs fags.
Values: n-1
(essentially, each different section)

m_l(Magnetic Quantum Number)- specifies the particular orbitals within a subshell where an electron is likely to be found at a given moment of time
Values: -l and +l
Possible value: 2l+ 1
(essentially, each box)

m_s (spin quantum number): indicates the spin orientation of an electron in an orbital.
-Have possible values of +1/2 and -1/2 only
-If two electrons are in the same orbital, they must have the opposite spin.
(essentially, the direction of each arrow)

Question 24

What are the maximum numbers of electrons that each shell can have?

Answer 24

2n²

Why? Because there can be 2 electrons per orbit

Question 25

What are the maximum number of electrons in a subshell?

Answer 25

2l+1

For a given shell, l, the number of subshells, m_l=(2l+1)

Since each subshell can accommodate 2 electrons of opposite spin, so maximum number of electrons in a subshell is (2(2l+1))= 2l+2

Question 26

What does the electron configuration of spectroscopic notation tell us?

Answer 26

It tells us the location of electrons.

Question 27

How do electrons fill the subshells?

Answer 27

Lowest first, then highes, or the n+1 rule.

Question 28

What is Pauli Exclusion principle?

Answer 28

No two electrons in a given atom can possess the same set of four quantum numbers

Question 29

What is the Aufbau principle?

Answer 29

Each subshell will fill completely before electrons begin to enter the next one

Question 30

What is the electron configuration of chromium?

Answer 30

Not what you think, it’s a little wonky.

Moving one electron from the 4s subshell to the 3d subshell allows for the 3d subshell to be half filled. Although moving the 4s electron up to the 3d orbital is energetically unfavorable, the extra stability from making the 3d subshell half-filled outweighs the cost.

Why? Sometimes there is reduced energy when ALL of the d subshells are half full, rather than partly half full.

Question 31

What is the electron configuration for Copper?

Answer 31

Why? A full d subshell outweighs the cost of moving an electron out of the 4s subshell. Other elements in the same group have similar behavior, moving on electron from the highest s subshell to the highest d subshell.

Question 32

What does paramagnetic mean?

Answer 32

materials have unpaired electrons that align with magnetic fields, attracting the material to a magnet

para=alongside

Question 33

What does diamagnetic mean?

Answer 33

materials have all paired electrons, which cannot easily be realigned, they are repelled by magnets

dia=across, through… not helpful

Question 34

How do you determine the maximum electrons in each shell?

How do you determine the maximum number of electrons in each subshell?

Answer 34

1. each Shell: 2n²
2. Each Subshell:4l+2