Unit 2 Review
NOVEMBER 10, 2014
Who where the two Greek philosophers?
And what did they believe?
Democritus
Matter is composed of atoms
Aristotle
Matter is made of fire, earth, air, and water
What is Dalton’s Atomic Theory
Dalton’s Atomic Theory is known as the start for our modern
atomic theory.
Proposed six postulates of atomic theory, only two of which
had to be changed.
What is an atom?
The smallest particle of an element that retains the properties
of the element.
JJ Thomson
Cathode ray tube experiments
◦ Electrons
◦ Charge to mass ratio
◦ Plum Pudding Model
Plum Pudding Model
Positively charged sphere containing electrons
Oil Drop Experiment
Robert Millikan
Charge and Mass of the electron
Ernest Rutherford
Gold Foil Experiment
◦ Alpha particles shot at gold foil
◦ Different deflection angles
◦ Positive charge must be centered in the atom
◦ Nucleus with protons
Rutherford’s Model of the atom
Positively charged particles (protons) located in the center of
the atom in the nucleus
Electrons around the nucleus
Neutron
James Chadwick
Subatomic particle with no charge, but equal mass of a proton
Atomic Number
Number of protons in an atom
And number of electrons in a neutral atom
Mass Number
Sum of the atomic number(or number of protons) and neutrons
in the nucleus
Atomic Mass
The weighted average atomic mass of all the isotopes of an
element, based on their natural abundance (percent
abundance)
Isotope
Atoms with the same number of protons but different numbers
of neutrons
What is the isotope notation of the element that
has an atomic number of 24 and a mass number
of 52?
What is the isotope notation for an
isotope of sulfur with a mass number of
33?
How many protons, neutrons, and
electrons does Cesium-134 have?
Protons: 55
Electrons: 55
Neutrons:79
Rubidium is a soft, silvery-white metal that has two common
isotopes, 85Rb and 87Rb. If the abundance of 85Rb is 72.2% and the
abundance of 87Rb is 27.8%, what is the average atomic mass of
rubidium?
(85 amu) x (0.722) = 61.37 amu
(87 amu) x (0.278) = 24.186 amu
61.37 amu + 24.186 amu = 85.556 amu  86 amu
Naturally occurring chlorine that is put in pools is 75.53% 35Cl
(mass = 34.969 amu) and 24.47% 37Cl (mass = 36.966 amu).
Calculate the average atomic mass.
(34.969 amu) x (0.7553) = 26.4120857 amu
(36.966 amu) x (0.2447) = 9.0455802 amu
26.4120857 amu + 9.0455802 amu = 35.4576659 amu 35.46 amu
What is the difference between the Bohr
model and the Quantum Mechanical model?
Bohr – only works for hydrogen, tries to describe an electrons path
around the nucleus
Quantum – treats electrons as waves, electron cloud(probability of
where an electron might be located
Both – limit the electron to principle energy levels
What is the difference between ground state
and excited state?
Ground – electrons are in the lowest allowable energy level
Excited – electrons have gained energy and are now in a higher
energy level
What happens when an electron falls from
the excited state to the ground state?
As the electron falls energy is released in the form of a photon of
light, depending how far the electron falls determines what
wavelength of light is released.
What do the principle energy levels tell
us?
1 – 7, tell us the relative size and energy of the atomic orbitals
What are the energy sublevels and what
do they tell us?
S, p, d, and f
The shape of the orbitals
What is the shape of the s, p, and d
orbitals?
List the electromagnetic series from
highest frequency to lowest frequency.
Gamma Rays  X-rays  Ultra-Violet  Visible Light
(V, I, B, G, Y, O, R)  Infrared  Microwaves  Radio
Waves
What is the relationship between
frequency, wavelength, and energy?
High Frequency: High Energy/Short Wavelength
Low Frequency: Low Energy/Long Wavelength
Green light has a frequency of 6.01 x 1014
Hz. What is the wavelength?
Calculate the energy of a photon of radiation
with a frequency of 8.5 x 1014 Hz.
E = hν
E = (6.626x10-34 J·s) x (8.5 x 1014 Hz)
E = 5.6 x 10-19 J
What is the photoelectric effect?
Photoelectrons are emitted from a metals surface when light of a
certain frequency shines on the surface
How many electrons can be held in the s
orbital sublevel?
2
How many orbitals and electrons are in
the p sublevel?
Orbitals: 3
Electrons: 6
How many orbitals and electrons are in
the d sublevel?
Orbitals: 5
Electrons: 10
How many orbitals and electrons are in
the f sublevel?
Orbitals: 7
Electrons: 14
What is Hund's Rule?
Single electrons with the same spin must occupy each equal energy
orbital before additional electrons with opposite spins can occupy
the same orbital
What is the Pauli Exclusion Principle?
States that a maximum of two electrons can occupy a single orbital
but only if the electrons have opposite spins
What is the Aufbau Principle?
State that each electron occupies the lowest energy orbital available
Fill from lowest to highest energy
Write the orbital diagram for
phosphorus.
Write the orbital diagram for fluorine.
Write the electron configuration notation
for Manganese.
1s22s22p63s23p64s23d5
Write the electron configuration notation
for tin.
1s22s22p63s23p64s23d104p65s24d105p2
Write the noble gas notation for Terbium.
[Xe] 6s24f9
Write the noble gas notation for barium.
[Xe] 6s2
Write the noble gas notation for
bohrium.
[Rn] 7s25f146d5
How many valence and inner electrons
does silicon have?
Valence: 4
Inner: 10
Inner electrons = total electrons – valence electrons
How many valence and inner electrons
does indium have?
Valence: 3
Inner: 46
How many valence and inner electrons
does rubidium have?
Valence: 1
Inner: 36
Draw the electron dot structure for
arsenic.
Draw the electron dot structure for tin.
Draw the electron dot structure for
strontium.
Things to remember:
Significant Figures
Rounding
Units/Labels
Write in complete sentences for free response
Test will be 28 Multiple choice (2pts each) and 2 free response (6pts each)