Chp. 1 Atomic Structure

Question 1

Found in the nucleus of an atom

Equal to the atomic number (Z)

Answer 1

Characteristics of protons

Question 2

Mixed with protons = most of an atom’s mass

Equal to the mass number (A) = Protons + This

Answer 2

Characteristics of neutrons

Question 3

• Atoms that share the same atomic number but have different mass numbers
• Exhibit similar chemical properties
• Differ in their number of neutrons

Answer 3

What is an isotope?

Question 4

Surround the nucleus at varying distances

If closer to the nucleus, they have lower energies

Answer 4

Characteristics of electrons

Question 5

• Farthest from the nucleus
• Love bonding and the outside environment
• Least electrostatic pull from the nucleus
• Weak interactions with the nucleus
• Sharing/transferring of these increases stability

Answer 5

Characteristics of valence electrons

Question 6

Equal to an atom’s mass number

Answer 6

Atomic mass

Question 7

• The weighted average of isotopes
• Half life can determine proportions of different isotopes
• Avogadro’s #: 6.02*10^23

Answer 7

Atomic weight

Question 8

• Determines the energy of a quantum

* E=hf, where h is a constant that equals 6.626*10^-34 Js

Answer 8

Plank relation

Question 9

An atom has a dense, positively charged nucleus that accounts for only a small portion of the atom’s volume

Answer 9

What did Rutherford postulate?

Question 10

Developed the first quantum theory that says energy that’s given off as electromagnetic radiation from matter comes in bundles (quaunta)

Answer 10

What did Planck postulate?

Question 11

The centripetal force acting on the electron as it revolved around the nucleus was created by the electrostatic force between the positively charged proton and the negatively charged electron.

Electrons follow a clearly defined pathway

Answer 11

What did Bohr postulate?

Question 12

Bohr’s equations

Answer 12

Angular momentum: L=nh/2pi
Electron energy: E=-RH/n^2 where RH=2.18*10^-18 Js
*Energy is directly proportional to the principal quantum number (n)

Question 13

• The state of lowest energy for an atom in which all electrons are in the lowest possible orbitals
• Most likely will happen at room temperature

Answer 13

What is ground state?

Question 14

• At least one electron has moved to a subshell of higher than normal energy
• Can be excited through heat and to different energy levels
• Results in energy absorption at specific wavelengths (absorption spectrum)

Answer 14

What is excited state?

Question 15

How do you determine the electromagnetic energy of photons?

Answer 15

E=hc/wavelength, where c is the speed of light = (3.00*10^8 m/s)

Question 16

Line spectrum: each line of the spectrum relates to a specific electron transition
Atomic emission spectrum: can be used as a fingerprint for an element; hydrogen is the simplest

Answer 16

Atomic emissions

Question 17

What are the different transitions to energy levels?

Answer 17

Lyman series: n greater/equal to 2 to n=2, which has larger transitions and shorter photon wavelengths

Balmer series: n greater/equal to 3 to n=3, which has 4 wavelengths in the visible region

Paschen series: n greater/equal to 4 to n=3

Question 18

What is the Heisenburg uncertainty principle?

Answer 18

It’s impossible to determine the momentum and position of an electron simultaneously

Question 19

What is the Pauli exclusion principle?

Answer 19

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

Position and energy of an electron by its quantum numbers = energy state

Question 20

Characteristics of the principal quantum number

Answer 20

• “n”
• The larger the n, the higher the energy level and radius of an electron’s shell
• Maximum # of electrons in a shell: 2n^2
• The difference in energy b/w 2 shell decrease as the distance from the nucleus increases

Question 21

Characteristics of the azimuthal quantum number

Answer 21

“l”

• Refers to size and number of subshells
• To find l in relation to n, l= n-1 (ex: n=1, l=0; n=2, l=0 and1)
• l=0= s subshell, l=1=p subshell, l=2=d subshell, l=3=f subshell
• Maximum # of electrons in a subshell: 4l+2

Question 22

Characteristics of the magnetic quantum number

Answer 22

“ml”

• Specifies the particular orbital
• For any possible values of l, ml= 2l+1 (ex: l=1, ml= -1, 0, 1)

Question 23

Shape of subshells

Answer 23

s: spherical
p: dumbbell

Question 24

Characteristics of the spin quantum number

Answer 24

“ms”

• Two spin orientation: -1/2 or 1/2
• If electrons are in the same orbital, they spin oppositely (paired)
• If electrons are in different orbital, ms values will be the same (parallel)

Question 25

What is the Aufbau principle?

Answer 25

Electrons will fill from lower to higher energy subshells. | Each subshell will fill completely before electrons start filling the next one.

Question 26

What is the n+l rule?

Answer 26

* The lower n+l is, the lower the energy of the subshell. * If 2 subshells have the same n+l value, the subshell with the lower n value has a lower energy and will fill with electrons first.

Question 27

Within a given subshell, orbitals are filled such that there are a maximum number of half filled orbitals with parallel spins (same ms values in different orbitals) Electrons in the same orbital tend to be closer to each other and end up repelling each other than those placed in different orbitals Half filled and fully filled orbitals have lower energies and higher stability

Answer 27

What is Hund's rule?

Question 28

What does paramagnetic mean?

Answer 28

Materials composed of unpaired electrons will orient their spins in alignment with a magnetic field, so the materials won't be as attracted to the magnetic field

Question 29

What does diamagnetic mean?

Answer 29

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

Question 30

Valence electrons

Answer 30

* Known as "active" electrons * Can be easily removed * Groups 1&2: highest s subshell e- are valence * Groups 13-18: highest s&p subshell e- are valence * Transition: highest s&d subshell e- are valence * Lanthanide & Actinide: highest s&f subshell e- are valence