CHAPTER 5

The Structure of

Atoms

Fundamental Particles

The following three _____________ particles make up atoms. The table below lists these particles together with their masses and their charges.

Particle Mass (amu) Charge

Electron (e-) 0.00054858 -1

Proton (p,p+) 1.0073 +1

Neutron(n,n0) 1.0087 0

Structure of the Atom Videos

1. The earliest modelshttp://www.youtube.com/watch?v=BhWgv0STLZs&feature=player_embedded

2. Smaller than the Smallesthttp://www.youtube.com/watch?v=WmmglVNl9OQ&feature=player_embedded

3. The Rutherford Modelhttp://www.youtube.com/watch?v=FfY4R5mkMY8&feature=player_embedded

4. The Bohr Modelhttp://www.youtube.com/watch?v=hpKhjKrBn9s&feature=player_embedded

5. Spectrahttp://www.youtube.com/watch?v=5z2ZfYVzefs&feature=player_embedded

6. Wave Mechanicshttp://www.youtube.com/watch?v=1bpG1lEjJfY&feature=player_embedded

Take notes over each video. Check calendar for due date.

The Atomic Weight Scale & Atomic Weights

define mass of 12C as 12 amu exactly1 ____________ = (1/12) mass of 12C

Ex. 1) Calculate the number of atomic mass units in one gram.

mass of one 24Mg atom = 24.3050 amuexperimentally determined1 mol of 24Mg atoms = 24.3050 g

__________________- weighted average of the masses of its constituent isotopes

Ex 2) Naturally occurring chromium consists of four isotopes. It is 4.31% 24

50Cr, mass = 49.946 amu, 83.76%

2452Cr, mass = 51.941 amu, 9.55%

2453Cr, mass = 52.941 amu, and 2.38%

2454Cr, mass = 53.939 amu. Calculate

the atomic weight of chromium.

Ex. 3)Naturally occurring Lithium exists as two isotopes, 6Li (mass = 6.015 amu) and 7Li (mass = 7.016 amu). The atomic weight is 6.941 amu. Which isotope is more abundant? Why?

Ex 4) The atomic number of boron is 10.811 amu. The masses of the two naturally occurring isotopes 5

10B and

511B, are 10.013 and 11.009 amu,

respectively. Which isotope is most common? Calculate the fraction and percentage of each isotope.› requires a little algebra› remember X + (1-X) = 1

Ex 5) Nickel has five isotopes that occur in the following percentages and isotopic masses. What is the isotopic mass of 60Ni?

Isotope Mass (amu) % 58Ni 57.935 68.27 60Ni ? 26.10 61Ni 60.931 1.13 62Ni 61.928 3.59 64Ni 63.928 0.91

Electronic ConfigurationsRules for assigning e- in orbitals:

1. Always fill orbitals in ________ energy level first. (Aufbau Principle)

__________________________- The electron that distinguishes an element from the previous element enters the lowest energy atomic orbital available. (in other words fill one energy sublevel before moving up)

2. No two e- can have _________ 4 quantum numbers in an atom.

(____________________________________)Wolfgang Pauli - 1925

› No two electrons in an atom may have identical sets of 4 quantum numbers.

3. _____________ e- out on a sublevel if possible. (Hund’s Rule)

Electrons will spread themselves out among the orbitals individually and give unpaired, parallel spins. The pairing of electrons is an __________________ process; energy must be __________________ in order to make it occur.

Exception: If you can achieve full or half-full orbitals by moving one e- between s ~ d or s ~ f orbitals, do so. It’s ______ in energy because there is an increased _____________due to the decrease in the screening of electron/nuclear attractions

Electronic Configurations

use periodic chart - best method

Electronic Configurations and Orbital Diagrams

1st row

22

11

1s He

1s H

ionConfigurat 1s

Orbital Order1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 6p 7s 5f 6d 7p 8s

2nd row

62210

5229

4228

3227

2226

1225

224

123

2p 2s 1s Ne

2p 2s 1s F

2p 2s 1s O

2p 2s 1s N

2p 2s 1s C

2p 2s 1s B

2s 1s Be

2s 1s Li

ionConfigurat 2p 2s 1s

3rd row

62

18

5217

4216

3215

2214

1213

212

111

3p s3 Ne NeAr

3p s3 Ne Ne Cl

3p s3 Ne Ne S

3p s3 Ne Ne P

3p s3 Ne Ne Si

3p s3 Ne Ne Al

s3 Ne Ne Mg

s3 Ne NeNa

ionConfigurat 3p 3s

4th row

orbitals. filled completely and filled-half with

associatedstability of measureextra an is There

3d 4s Ar ArCr

3d 4s Ar Ar V

3d 4s Ar Ar Ti

3d 4s Ar Ar Sc

4s Ar ArCa

4s Ar ArK

ionConfigurat 4p 4s 3d

5124

3223

2222

1221

220

119

4th row continued

reason. same y theessentiallfor

andCr like exceptionAnother

3d 4s Ar Ar Cu

3d 4s Ar Ar Ni

3d 4s Ar Ar Co

3d 4s Ar Ar Fe

3d 4s Ar Ar Mn

ionConfigurat 4p 4s 3d

10129

8228

7227

6226

5225

4th row continued

6102

36

510235

410234

310233

210232

110231

4p 3d 4s Ar ArKr

4p 3d 4s Ar ArBr

4p 3d 4s Ar Ar Se

4p 3d 4s Ar Ar As

4p 3d 4s Ar Ar Ge

4p 3d 4s Ar ArGa

ionConfigurat 4p 4s 3d

______________________is an analytical technique that measures the mass-to-charge ratio of charged particles. It is most generally used to find the ____________ of a sample by generating a mass spectrum representing the masses of sample components. The ____________________is measured by a mass spectrometer.

http://www.youtube.com/watch?v=J-wao0O0_qM

Mass Spectrometry & Isotopic Abundances

This technique is applicable in: ___________ unknown compounds by the mass

of the compound molecules or their fragments determining the _______________________of

elements in a compound determining the structure of a compound by

_________________its fragmentation ______________ the amount of a compound in a

sample using carefully designed methods studying the fundamentals of gas phase ion

chemistry (the chemistry of ions and neutrals in vacuum)

________________other important physical, chemical, or even biological properties of compounds with a variety of other approaches

Electromagnetic Radiationrelationship for electromagnetic radiationc = l u

c = ____________________= 3.00 x 108 m/s

Max Planck - __________› energy is quantized› light has particle character

Planck’s equation

Ex. 6) What is the frequency of green light of wavelength 5200 Å?

Ex. 7) What is energy of a photon of green light with wavelength 5200 Å?

Photoelectric Effect

_____________ – have mass, volume, and are countable._____________ – light composed of particles

•light has _______________________ behavior•light can strike the surface of some metals and cause an electron to be ejected

Ex. ~ electronic door openers~ light switches for street lights~ exposure meters for cameras

• Albert Einstein explained the ____________________________in 1905› 1921 Nobel Prize in Physics

electrons are _______________b/c energy from a photon transfers to e- during collisions. If you increase energy, more electrons get kicked off. Each individual photon makes a spark, 1 e- per photon. The more intense the light, the more photons. Light strikes the surface of various metals and causes ______________ to be ejected.

Atomic Spectra________________________

electric current passing through a gas in a vacuum tube (at very low pressure) causes the gas to_______light

emission or bright line spectrum

___________________________shining a beam of white light through a sample

of gas gives an ______________ spectrum

shows the wavelengths of light that have been ____________

Spectra are fingerprints of elements

use spectra to __________ elements

can even identify elements in_____

The Origin of Spectral Lines Light of a characteristic wavelength (&

frequency) is ________ when electron ____ from ________ E (orbit) to ________ E

(orbit)origin of emission spectrum

light of a characteristic wavelength (& frequency) is ____________ when electron ________ from ________ E

(orbit) to _________ E (orbit)origin of absorption spectrum

Atomic Spectra how atoms ________ to us”

› we have to interpret their language Bohr, Schrodinger, and Heisenberg

were some of the first scientists to translate the language of atoms

Ex. 8) An orange line of wavelength 5890 Å is observed in the emission spectrum of sodium. What is the energy of one photon of this orange light?

Quantum Mechanics Werner Heisenberg - 1927

› ________________________________

It is ________________ to determine simultaneously both the position & momentum of an electron. Why? The act of measuring a very small particle changes its position, so it is _____________ to precisely determine both the ___________ and _______________ of that object.

› electron microscopes use this phenomenon› devices for detecting motion of electron disturbs its

position

Quantum Numbers

______________ numbers are description of the orbitals; solutions of the Schrodinger, Heisenberg & Dirac wave equations

the quantum #’s help ________________ the solutions

There are four ___________ numbers which describe the relative position and energy of an electron in an atom.

1st ____________ quantum number

2nd ____________________quantum number

3rd ______________ quantum number

4th _______ quantum number

Principal Quantum Number

Symbol “_____” – refers to energy level

n = 1, 2, 3, …

The principal quantum number describes the ________________from the nucleus. It is often referred to as ______________or _______

electron’s ________depends principally on n

Angular momentum, 2nd quantum number

angular momentum, tells __________ of the atomic orbitals

_______________- ________of space where the _________________of finding an electron around an atom is _____________

~ volume that the electrons occupy ___________of the time

How to solve for Angular momentum

symbol ___ to find ℓ plug into n-1

If n=1 ℓ =0

If n=2ℓ = 0, 1

If n=3ℓ = 0, 1, 2

If n=8

Orbital symbols for ℓ

represents the ______ within an energy level: s, p, d, f

(code letters for the shapes of orbitals) s=0 p=1 d=2 f=3

Quantum number - ℓ (in theory)If ℓ = 0, 1, 2, 3, 4, 5, .......(n-1)Then ℓ = s, p, d, f, g, h, .......(n-1)

s orbitals

s orbitals are __________ in shape.

Every energy level has an s orbital

s orbitals have angular momentum quantum number (l) equal to 0.

For s:

p orbitalsp orbitals are shaped like dumbbells or peanuts.

They are oriented along the x, y, and z coordinates.

______________________

They have an angular momentum quantum number (l) equal to 1.

For p:

3 per n level, px, py, pz

p orbitals

d orbitals

_______________________

4 clover leaf shaped and 1 peanut shaped with a doughnut around it

on Cartesian axes and rotated 45o

For d:

5 per n level

d orbitals

f orbitals

__________________ most complex shaped

orbitals7 per n level, complicated names

For f: important effects in lanthanides & actinides

f orbitals

Magnetic quantum numbers 3rd quantum number

symbol m l

Helps tell _______________ of orbitals

m l = - l to + l

Look at _____________________to help you with m l

theoretically, we can continue this series on to g, h, i, orbitals

l =0

m l =0 › only 1 value for s orbital

l =1

m l = -1, 0, 1› 3 values for p orbitals

l =2

m l = -2, -1, 0, 1, 2› 5 values for d

orbitals

l =3

m l =› 7 values for f orbitals

Spin Quantum Number

4th quantum number, symbol = _______› ms = +1/2 or -1/2

tells us the ________ and _____________ of the ____________ field of the ____________

spin effects› every orbital can hold up to two electrons› one spin up one spin down ¯

spin describes the ______________of their ________________ field

e- have charges

two _________________ magnetic states

Diamagnetic vs. paramagnetic

paired electrons have spins unaligned ̄› no net magnetic field

Called ____________________ - __________by a magnetic field, all electrons are __________

unpaired electrons have their spins aligned or ¯¯› enhanced magnetic field

Called ________________- ___________to a magnetic field, has _____________electrons

Finding Quantum numbers Let’s find the complete set of quantum

numbers for the electrons in Na and Fe

(look at electron configurations/orbital diagrams 1st)

11Na› must have one set of 4 quantum numbers

for each of the 11 electrons in Na

26Fe› should have one set of 4 quantum

numbers for each of the 26 electrons in Fe

Some vocab

__________________– lowest energy/most stable state of an atom, molecule, or ion. Fills one sublevel before moving up, follows Aufbau Principle.

_____________– orbitals skipped, does not follow Aufbau Principle

_____________________– very wrong or not possible

_______________ – different elements that have the same electron configuration b/c of gaining or losing electrons.

___________________- negatively charged electrons prevents higher orbital electrons from experiencing the full nuclear charge by the repelling effect of inner-layer electrons

________________________- the net positive charge experienced by an electron in a multi-electron atom

group names on the P.T. ~ Representative elements

_______________________ elements: group __(the last electron fills s or p levels) IA – alkali metals IIA – alkaline earth metals IIIA – boron famly IVA – carbon family VA – pnictogens or nitrogen family VIA – chalcogens or oxygen family VIIA – halogens VIIIA – noble gases

group names on the P.T. ~ the rest…

__________________________(filling d level) 3 - the scandium family 4 - the titanium family 5 - the vanadium family 6 - the chromium family 7 - the manganese family 8 - the iron family 9 - the cobalt family 10 - the nickel family 11 - the coinage or copper family 12 - the zinc family

Lanthanide series (filling 4f level) Actinide series (filling 5f level)

Extra credit1) In a universe far far away, the laws

of quantum mechanics are the same as ours with one small change. Electrons in this universe have three spin states, -1, 0, and +1, rather than the two, +1/2 and -1/2, that we have. What two elements in this universe would be the first and second noble gases? (Assume that the elements in this different universe have the same symbols as in ours.)

2) A) What is the atomic number of the element that should theoretically be below Ra? B) Its chemical behavior would be most similar to which elements? C) How many valence electrons would it have?D) Its electron configuration would be?E) An acceptable set of 4 quantum numbers for the last electron in this element would be?F) What would you name it?