Atomic Structure

Question 1

What are protons?

Answer 1

Positively charged subatomic particles residing in the nucleus of an atom

Has a charge of +1 and mass of 1amu

Question 2

Explain what is the Atomic Number (Z) of an atom.

Answer 2

Number of atoms in the nucleus of an atom

Used as identifier of elements

Question 3

What are neutrons?

Answer 3

Neutral charged subatomic particles

Question 4

Explain what is the Mass Number (A) of an element.

Answer 4

Sum of protons and neutrons in an atom

Question 5

Explain what isotopes are.

Answer 5

Atoms that share the same number of protons, but have different number of neutrons

Question 6

Explain what is the Atomic Mass of an element.

Answer 6

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

Question 7

Explain what is the Atomic Weight of an Element.

Answer 7

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

Question 8

What are valence electrons?

Answer 8

farthest electrons from the nucleus and because they are so far, they feel the least amount of electrostatic pull from the nucleus and therefore can bond with others

most easily removed “active electrons

Question 9

Describe the relationship between distance from the nucleus and energy level of an electron.

Answer 9

electrons closer to the atom nucleus have lower energy levels and farther away have higher energy levels

Question 10

Which subatomic particle is most important for determining: charge?

Answer 10

Electron

Question 11

which subatomic particle is most important for determining: atomic number?

Answer 11

proton

Question 12

which subatomic particle is most important for determining: isotope?

Answer 12

neutron

Question 13

half-life correspond with ____ therefore helps determine ____

Answer 13

stability, the relative proportions of these different isotopes

Question 14

Describe the relationship between atomic weight, isotopes, and moles.

Answer 14

the atomic weight of carbon is 12 amu, which means the average carbon weighs 12 amu (meaning carbon 12 isotope is extremely more abundant than 13 or 14) and one mole of carbon atoms is equal to 12 grams

Question 15

Ernest Rutherford

Answer 15

experimental evidence that an atom has a dense positively charged nucleus that one accounts for a small portion of the atom’s volume (VOLUME)

Question 16

Max Planck

Answer 16

developed first quantum theory - energy emitted as electromagnetic radiation for matter comes in discrete bundles called quanta (the energy of a quantum is given by the Planck Relation)

Question 17

Write the equation that describes Plank Relation.

Answer 17

E=h*f

Question 18

Planck’s Constant

Answer 18

h, frequency of the radiation (in Planck’s relation)

Question 19

Describe Neils Bohr’s atomic model.

Answer 19

electron traveled in a circular orbit around the central proton nucleus, this centripetal force acting on the electron is from the electrostatic force between positive protons and negative electrons (used the work of Rutherford and Planck)

Question 20

Describe Bohr’s use of Planck’s constant.

Answer 20

placed restrictions on the angular momentum that drove the pathways of electrons (previously pathways were defined by classic physics)

L=(n*h)/2pi

because n is the only variable, the angular momentum can only change in discrete amounts respective to the quantum number

Question 21

what are the similarities between quantized angular momentum and Planck’s concept of quantized energy?

Answer 21

There is only discrete energy levels possible, energy isn’t infinite

Question 22

what is the energy of the electron equation saying? (E=-Rn/n^2)?

Answer 22

as the energy of an electron increases, aka becomes less negative, the farther out from the nucleus it will be located (larger n)

important point: while magnitude of the fraction is getting smaller, the actual value it represents is getting larger (becoming less negative)

Question 23

What is the Rn?

Answer 23

Rydberg unit of energy

Question 24

What is the ground state?

Answer 24

n=1 (lowest and smallest energy radius)

Question 25

What did Bohr said about electron orbits?

Answer 25

bohr said that electrons revolved in a defined pathway at a discrete energy value, and that with the transfer of energy (gaining) they could “jump” to higher energy orbits or “fall” with the loss of energy (he likened the electrons orbiting the nucleus the way the planets do with the sun)

Question 26

all systems tend toward ________ _________

Answer 26

minimal energy (lowest energy = more stability)

Question 27

atomic emission spectra

Answer 27

E=(h*c)/lamda

Question 28

when electrons return close to their ground states, they will

Answer 28

emit a photon with a wavelength characteristic of the specific energy transition it undergoes

Question 29

atomic emission spectrum

Answer 29

each element has unique emissions from when the electrons change energy levels (because they all have distinct energy levels) so that line spectrum can be used as a fingerprint for that element

Question 30

Lyman series

Answer 30

transition from energy level n=1 to energy level n=2 or higher – larger energy transitions so shorter photon wavelengths (i dont get that ask doctor nataro page 13)

Question 31

Balmer series

Answer 31

transition from energy level n=2 to energy level n=3 or higher

Question 32

Paschen series

Answer 32

transition from energy level n=3 to energy level n=4 or higher

Question 33

positive E correlates to _____ and negative E from the equation correlates to _______

Answer 33

emission, absorption

Question 34

Heisenberg uncertainty principle

Answer 34

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

to determine position the electron must stop (confused by this ask nataro page 16)

Question 35

What are the 4 quantum numbers?

Answer 35

n, l ,ml , ms

Question 36

Pauli exclusion principle

Answer 36

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

Question 37

Describe the relationship between n, l, ml, ms.

Answer 37

the value of n limits the value of l, which in turn limits the value of ml, ms is either +/- 1/2`

Question 38

principal quantum number (n)

Answer 38

the larger the integer value of n, the higher the energy level and radius of the electron’s shell (within each shell there is a capacity to hold a certain number of electrons)

Question 39

maximum number of electrons within a shell

Answer 39

2n^2

Question 40

difference in energy levels

Answer 40

the distance between n=1 and n=2 is the largest (when only moving one level) n=3 and n=4 is smaller, this makes sense when you think of 1/(n-i)^2 - 1/(n-f)^2

Question 41

azimuthal quantum number (l)

Answer 41

shape and number of sub shells within a principle energy level (shell)

important implications for chemical bonding and bond angles

Question 42

magnetic quantum number (ml)

Answer 42

specifies the particular orbital within a sub shell where an electron is most likely to be found at a given moment in time

the possible values are between -1 and +1 (including 0)

Question 43

for any n, this produces ___ orbitals and a maximum of ____ electrons (two per orbital)

Answer 43

n^2, 2n^2

Question 44

spin quantum number (ms)

Answer 44

electron has two spin orientations designated +1/2 and -1/2

Question 45

Describe what happens to electons on the same orbital.

Answer 45

whenever two electrons are in the same orbital, they must have opposite spins

Question 46

Describe the aufbau principle (building-up principle).

Answer 46

electrons fill from lower to higher-energy subshells and each subshell will completely fill before electrons begin to enter the next one

Question 47

What is the n + l rule (important for test day)?

Answer 47

the lower the sum of the values of the first and second quantum numbers, the lower the energy of the subshell

Question 48

Describe the electron configuration of an ion: anion / F- and cation / Fe3+.

Answer 48

anion: electrons fill the same way that they normally would

[He]2s^2 2p^6

cation: start with the neutral atom and remove electrons from the subshells with the highest n value first, then electrons are removed from the subshell with the highest l value among these

[Ar]3d^5

Question 49

In subshells that contain more than one orbitals, the orbital fills in accordance to this rule

Answer 49

Hund’s Rule

Question 50

Hund’s Rule (bus rule)

Answer 50

within a given subshell, orbitals are filled such that there are a maximum number of half-filled orbitals with parallel spins (they fill so each has their own orbital before doubling up, like a school bus)

Question 51

A consequence of Hund’s rule is

Answer 51

half-filled and fully filled orbitals have lower energies (higher stability) than other states

Question 52

the consequence of Hund’s rule creates two notable exceptions to electron configurtoin that are often tested on the MCAT:

Answer 52

chromium (and other elements of that group) and copper (and other elements in its group)

3d^4 becomes 3d^5
3d^9 becomes 3d^10

Question 53

Explain what are Paramagnetic Materials.

Answer 53

composed of atoms with unpaired electrons that orient their spins in alignment with a magnetic field, so the material is weakly attracted to the magnetic field

PARAmagnetic = magnetic field that causes PARAllel spins in unpaired electrons and therefore cause an attraction

Question 54

Explain what are diamagnetic materials.

Answer 54

atoms that only have paired electrons will be slightly repelled by a magnetic field

Question 55

how do elements in period three (starting with sodium) and below violet the octet rule? (will be discussed more in chapter 3)

Answer 55

they may accept electrons into their d subshells, which allows them to hold more than eight electrons in their valence shell

Question 56

Valence electrons for Group IA and IIA

Answer 56

the highest s subshell electrons

Question 57

Valence electrons for Group IIIA through VIIIA (13-18)

Answer 57

the highest s and p subshell electrons

Question 58

Valence electrons for transition elements

Answer 58

in the highest s and d subshells (even though they have different principal quantum numbers)