exam 3 - chapter 6 Electronic Structure of Atoms

wavelength

distance between two peaks

frequency, v

number of peaks to pass a given point per second

3.00 × 10⁸ m/s

speed of light, c =

hv

(v = c/wavelength) sooooo Ephoton = hc/wavelength

E_photon =

wavelength x frequency(v)

c =

6.626 × 10^-34 Jxs

value of h =

electromagnetic spectrum

visible light is only a tiny portion of the ____

high frequency and high energy

short wavelength has ____

;pw frequency and low energy

long wavelength has _____

slide 6 of notes image!

general order of the different types of radiation with respect to energy

line spectrum

does not have every color . discharge tubes emit it

white light

a continuous spectrum is produced when ____ is directed through a prism.

Bohr’s model

the problem is that the current model of the atom (nuclear) does not correctly predict these observed line, so the new model is ____

only orbits a certain radii, corresponding to certain specific energies, are permitted for the electron in a hydrogen atom

Bohr’s 1st Postulate

an electron in a permitted orbit is in an allowed energy state. an electron in an allowed energy state does not radiate energy and therefore does not spiral into the nucleus

Bohr’s 2nd Postulate

energy (light) is emitted or absorbed by the atom only when the electron changes from one allowed energy state to another

Bohrs 3rd Postulate

energy and energy levels

the of the photon is related to the energy differences between ___

• n increases “e- jumps”

• atom gains energy

• endothermic process (change E = +)

if a hydrogen atom absorbs a photon":

• n decreases “e- falls”

• atom looses energy

• exothermic process (change Eatom = - )

if a hydrogen atom emits a photon:

standing wave

the de Broglie model treats the electron as a ____

h/mv

de Broglie wavelength equation =

decreases

as mass increases, wavelength

long wavelengths

because the amss increases and wavelength decreacreases, electron have _____

short wavelengths

ordinary objects have ___

uncertainty in position

change x =

uncertainty in momentum

change mv =

(change x)(changemv) > h/4pie

heisenberg’s uncertainty principle

because electron is at known radius

why does bohrs model violate the uncertainty principle?

Schrodinger’s model

whose model does not violate the ucnertainty principle?

quantum superposition

the idea that electrons are hard to locate with high precision

2

each box is an oribital with __ electrons

quantum mechanics

new type of math to describe energy of a system, but it’s still based on ideas we already know

energy levels know exactly, position electron known exactly

bohr model

energy levels known exactly, but position possesses large uncertainty

schrodinger model

energy (size) and shape.

n, l, m_l, m_s

oribitals have quantum numbers that describe their ____

1) size , n (describe energy)

2) shape, l (describe shape)

3) orientation, m_l (describe orientation of the orbital)

each wave function has three characteristic quantum numbers association with it

identifies the shell that determines an average distance from the nucleus

n :

1) size orbital increases

2) energy of orbital increases

as n increases we see:

identifies the subshell that determine shape of the atomic orbital

secondary quantum number , l :

0,1,2,…. (n-1)

l ranges:

letter

subshells (l) have __ designations

0 → s

1 → p

2 → d

3 → f

4 → g

what are the letter designations (l)?

determines the orientation of the oribiatl and depends on the subshell

magnetic quantum number, m_l :

0 (1box)

m_l for s (l=0)

-1, 0, 1 (3 boxes)

m_l for p (l=1)

-2, -1, 0, 1, 2 (5 boxes)

m_l for d (l=2)

no two electrons in an atom can have the same set of all 4 quantum numbers n, l, m_l, m_s

Pauli Exclusion Principle

number of angular nodes in an orbital shape

l also =

0

angular nodes in s orbital =

number of times graph goes to 0 probability

= n - l - 1

radial node:

1

p orbital angular node =

2

d orbital angular nodes =

3

f orbital angular nodes =

aufbau principle

Building up: electrons are placed in the lowest energy atomic orbitals first

pauli exclusion principle

electrons are fermions. no two fermions can be in exactly the same in terms of position, energy. this means every electron must have a different set of quantum numbers

hunds rule

for degenerate orbitals, the energy is maximized when the same spin is maximized

degenerate

energy levels that are at the same energy

valence electrons

the outermost electrons on an atom

#of valence electrons on an atom = group number or all electrons in the highest n

valence electrons for main group elements (s and p block)

#electrons in highest ns + (n-1)d

VE for early d-block metals

only count outermost ns electrons in the VE count because a filled d block becomes very stable

VE for later d-block metals