Basic Chemistry
Unit 3
Hobbs
1. Bell Ringer: Thursday,
09.25.14
Because of the Doppler Effect, when the
source of the sound is coming toward
you, you will hear
a. the sound gets quieter
b. a decrease in pitch
c. an increase in pitch
d. no change in sound
2. Bell Ringer: Friday, 09.26.14
Weekly
Review 3
DUE
TODAY
Name the energy
transformations within this
system.
3. Bell Ringer: Monday, 09.29.14
What are three things you find in an
element square?
a. atomic number, mass number,
chemical symbol
b. mass number, chemical symbol,
weighted average
c. atomic number, chemical symbol,
isotope
d. avogadro’s number, symbol, mass
number
THIS THURSDAY IS ZOMBIE DAY!!!
4. Bell Ringer: Tuesday,
9.30.2014
Cobalt- Cobalt# of
protons
# of
30
neutrons
# of
electrons
33
TOMORROW IS ZOMBIE DAY!!!
5. Bell Ringer: Wednesday,
10.1.14
What determines the identity of
the element?
–A. protons
–B. neutrons
–C. electrons
–D. quarks
TOMORROW IS ZOMBIE DAY!!!
MIDTERM
•
•
•
•
•
Scantron
Hints
Calculator
Pencil
Scratch Paper
• Turn into MY desk
once you are
done!!!
• STUDY FOR OTHER
MIDTERMS once
you are done!!
• NO TALKING UNTIL
EVERYONE IS
DONE!!
6. Bell Ringer: Thursday, 10.2.14
• Phosphorous-31
# of protons
# of neutrons
# of electrons
7. Bell Ringer: Friday, 10.3.14
• Draw the Bohr Model
for Aluminum.
8. Bell Ringer: Monday,10.6.14
• Which is the smallest piece of matter
that still retains the property of the
element?
• A. atom
• B. quark
• C. neutron
• D. proton
Thursday is CAMO DAY!
Complete the following Bohr
Models…by yourself no talking
Be
Al-28
2+
Mg
9. Bell Ringer: Tuesday,
10.7.2014
A chemical symbol represents the
____ of an element.
• A. Element name
C. Group
• B. Reaction
D. Structure
Thursday is CAMO DAY!
Bohr Model Check
Draw the following…
N
2+
Ca
S-34
10. Bell Ringer: Wednesday,
10.8.14
SPS 1
+2
• Mg
Quiz
Today
-what is the element?
-# of protons
-# of neutrons
-#of electrons
TOMORROW is CAMO DAY!
Coloring Periodic Table
Change gray  light
blue
Change pink  purple
Change purple  brown
(transition metals)
12. Bell Ringer: Tuesday,
10.14.14
• An atom that has lost or gained
electrons is a(n)
a. isotope
c. ion
b. noble gas d. nucleus
THURSDAY is TIE DAY
11. Bell Ringer: Thursday,
10.9.14
• How many electrons are needed in
the outer energy levels of most
atoms for the atom to be chemically
stable?
a. 2
b. 4
c. 6
d. 8
11.Bell Ringer: 03.13.14
• Name one of the
families on The
Periodic Table.
12. Bell Ringer:
Wednesday, 10.15.14
Hydrogen is grouped with the
alkali metals because it ____.
a. is a gas
b.is a metal
c. is a solid
d.has 1 valence electron
THURSDAY is TIE DAY
12. Bell Ringer: Tuesday,
03.18.14
• What type of radiation has no
mass or charge and is an
energetic form of light?
–A. alpha
–C. gamma
B. beta
D. nuclear
14. Bell Ringer: Thursday,
03.20.14
• Thorium-234 has a half-life
of 24 days. If you started
with a 100-g sample of
thorium-234, how much
would remain after 48 days?
09.25.14
• Pick an element from 518-519 or the
back page of the book and create an
element square for that element with
all of its correct information.
Agenda: 03.03.14
•
•
•
•
Finish U2 test (MC and WP)
Launch U3/Pre-Test
Unit 3 Notes
Practice Elements
Vocabulary
• Atoms: Smallest particle of an element that
has all the properties of matter:
– Protons- particles in the nucleus with positive
charge
– Electrons- particles orbiting around nucleus with
negative charge
– Neutrons- particles in the nucleus with no charge
• Elements: Simplest form of a pure substance
• Compounds: Two or more elements chemically
combined to form a new substance
Sub-Atomic Particles
Part of Atom
Charge
Location
Mass/Size
Electron
- negative
outside
nucleus
.0006 amu
(too little to count)
Proton
+ positive
inside
nucleus
1 amu
Neutron
no charge
inside
nucleus
1 amu
Cobalt- Cobalt-
# of
protons
# of
30
neutrons
# of
electrons
33
Argon-42
# of
18
protons
# of
neutrons
# of
electrons
Argon-46
18
# of
19
protons
# of
42
neutrons
# of
electrons
19
44
Radon224
# of
86
protons
# of
neutrons
# of
electrons
Radon230
86
Ions
• Ion - an atom that has lost or gained
electrons
• Two types of IONS
• Cation – An atom or a molecule which is
positively charged, so it has more number of
protons than electrons.
• Anion - An atom or a molecule which is
negatively charged, so it has more number of
electrons than protons.
• An atom that has a charge is an ION
Ions (extended sub-atomic
particles)
• Cation – An atom or a molecule which
is positively charged, i.e. has more
number of protons than electrons.
• Anion - An atom or a molecule which is
negatively charged, i.e. has more
number of electrons than protons.
Periodic Table
Using the Periodic Table
17

Atomic Number
– Equal to # protons = # electrons
– Periodic Table is arranged by this
number
Cl
35.5

Symbol
– “Shorthand” for the element – Note 2nd letter
is always lowercase

Atomic Mass Number
– Total AVERAGE mass of Protons + Neutrons
+ Electrons
Atomic Mass – Fractions?
Look at Chlorine (atomic number 17)
 Atomic mass of 35.5? I dont’ get it!
 Where does the 35.5 come from?

– 0.5 protons? 0.5 neutrons?  No

Atomic Mass = average number of
protons and neutrons in nature
Bohr Models
1. Bohr models are used to predict
reactivity in elements.
2. Reactivity refers to how likely an
element is to form a compound with
another element.
3. When looking at Bohr models, we
look at its valence electrons (the
electrons on the last energy level) to
determine reactivity.
Bohr Models
1. Draw the nucleus.
2. Write the number of neutrons and the
number of protons in the nucleus.
3. Draw the first energy level.
4. Draw the electrons in the energy levels
according to the guidelines. Make sure
you draw the electrons in pairs.
5. Keep track of how many electrons are
put in each level and the number of
electrons left to use.
Isotopes


An isotope is a variation of an element
(same protons) but can have diff. # of
neutrons
Isotopes are identified by their mass
numbers

Written with element name and mass
number OR chemical symbol and mass
number

Ex: carbon (atomic mass = 12.011)
– Carbon (14) and carbon (12) exist in
nature
Isotopes
• Reading Essentials Books – if
finished with both practice
sheets!
– Pages 288-292
– Respond to all questions under
headings and the “AFTER YOU
READ”
– DO NOT CREATE FOLDABLE!
Guided Practice
• In order to draw Bohr models of these elements, you
must first determine the number of protons, neutrons,
and electrons. Once you have found this information,
follow the directions to draw your model.
6
C
Carbon
12.011
Protons: ____
Neutrons: _____ Electrons: ______
How many energy shells will this have? ____
How many valence (outer) electrons does this element have?
____
Bohr Model:
Valence Electrons
Electron Energy Levels
• Electrons are arranged in “Shells” around nucleus in
predictable locations
• Fill “seats” closest to nucleus first (concert – best
seats)
• “Seats” available
–
–
–
–
–
–
Shell #1
Shell #2
Shell #3
Shell #4
Shell #5
Shell #6
2 electrons
8 electrons
8 electrons
18 electrons
32 electrons
50 electrons
• Ex. Carbon has 6 total electrons so…
Two electrons on first energy level
Four electrons on second energy
level
Question: Could we fit more electrons on the second energy level if there were more electrons in carbon?
Ions
• An atom usually has a neutral charge.
That means it has the same number of
protons as electrons
• Remember, a proton has a positive charge and
an electron has a negative charge
• ION – an atom that has lost or gained
one or more electrons and has become
charged either positively or negatively
Ions - Cations
• When an atom LOSES electrons, it
becomes more POSITIVE
– Why?
• If you are getting rid of negative
particles (electrons) but your number
of positive particles (protons) are
staying the same.
– In other words, you are subtracting
negative numbers
Ions-Cations
• What would the charge be if:
• The neutral form of Gold (Au) lost 4 of
its 79 electrons. It now has 79 protons
and 75 electrons
• The neutral form of Mg lost 2 of its 12
electrons. It now has 12 protons and
10 electrons.
Ions-Anions
• When an atom GAINS electrons it
becomes more NEGATIVE
– Why?
• Electrons have a negative charge, so
the more you have, the more negative
you become
Ions
• Ions are represented by placing a
“superscript” charge number next to
the atomic symbol.
• Ex.
– O-2 = oxygen with a negative 2 charge
– K+ = potassium with a positive 1 charge
– N-3 = nitrogen with a negative 3 charge
– And so on
Ions
+2
Mg
Ions
+2
Ca
Ions
+1
K
Ions
-1
Cl
Atomic Structure
Total # of protons and electrons (in a neutral atom)
17 protons in nucleus
17 electrons orbiting nucleus
17
Cl
Element Name
Chlorine
35.5
Total Mass of Nucleus
36 - 17 = 18 neutrons
(Round Atomic Mass)
Notice: electrons follow energy level rules
Valence Electrons




An electron on the outermost energy shell of an
atom
Important to understand because this is a key
factor in how atoms will BOND with each other
Octet rule – stable atom will have 8 electrons in
that outer shell
Practice – Valence # of
– Chlorine?
– Neon?
– Nitrogen?
– Oxygen?
Types of Chemical Bonds
• Ionic- Two elements bond by transferring electrons to create
ions that attract together (+ is attracted to - after an electron is
transferred)
• Covalent- Two elements bond by sharing electrons
(strongest bond type)
• Metallic- Two metals bond and form a “common electron
cloud”. This is a cluster of shared electrons (weakest bond type)
Polarity
• Some electrons are not shared evenly in
covalent bonds.
• One end, or pole, of the molecule has a
partial negative charge while the
opposite pole has a partial positive
charge.
• Poles attract opposite charges – polar
substances dissolve in water
• Nonpolar substances do not dissolve in
water
Hydrogen Bonds
• Hydrogen bonded to O, N, or F has a
partial positive charge.
• These hydrogens attract the negative
pole of nearby molecules.
• This forms a hydrogen bond.
Trends
• Use the paper as your
instructions
• Use Chapter 19 as a guide for
placement of where and how
many
The Periodic Table
• The periodic table organizes the
elements in a particular way. A great deal
of information about an element can be
gathered from its position in the periodic
table.
• For example, you can predict with
reasonable good accuracy the physical
and chemical properties of the element.
You can also predict what other elements
a particular element will react with
chemically.
The Periodic Table
The Periodic Table
Properties of Metals
• Metals are good conductors of heat
and electricity.
• Metals are shiny
• Metals are ductile (can be stretched
into thin wires).
• Metals are malleable (can be pounded
into thin sheets).
• A chemical property of metal is its
reaction with water which results in
corrosion.
Properties of Non-Metals
• Non-metals are poor conductors of heat and
electricity.
• Non-metals are not ductile or malleable.
• Solid non-metals are brittle and break easily.
• They are dull.
• Many non-metals are gases.
Properties of Metalloids
• Metalloids (metal-like) have properties of
both metals and non-metals.
• They are solids that can be shiny or dull.
• They conduct heat and electricity better
than non-metals but not as well as metals.
• They are ductile and malleable.
Families Periods
• Columns of elements are
called groups or families
• Elements in each family
have similar but not
identical properties.
• For example, sodium
(Na), potassium (K), and
other members of family
IA are all soft, white,
shiny metals.
• All elements in a family
have the same number of
valence electrons.
• Each horizontal row of
elements is called a
period.
• The elements in a period
are not alike in
properties.
• In fact, the properties,
change greatly across
any given row.
• The first element in a
period is always an
extremely active solid.
The last element in a
period, is always an
inactive gas.
Valence Electrons
• Valence electrons are the electrons in the outer
energy level of an atom.
• These are the electrons that are transferred or
shared when atoms bond together.
• All elements in a family have the same number of
valence electrons.
Alkali Metals
• Atoms of the alkali
metals have single
electron in their
outermost level, in
other words, 1
valence electron.
• They are shiny, have
the consistency of
clay, and are easily
cut with a knife.
• They are the most
reactive metals.
• They react violently
with water.
• Alkali metals are
never found as free
elements in nature.
They are always
bonded with
another element.
Alkaline Earth Metals
• They are never found uncombined in
nature
• They have two valence electrons
• Alkaline earth metals include
magnesium and calcium, among
others.
Halogen Family
• Halogens have 7 valence electrons,
which explains why they are the most
active non-metals.
• They are never found free in nature.
They are diatomic.
• They react with alkali metals to form
salts.
Noble Gases
• Noble Gases are colorless gases that are
extremely un-reactive.
• One important property of the noble
gases is their inactivity. They are inactive
because their outermost energy level is
full.
• Because they do not readily combine with
other elements to form compounds, the
noble gases are called inert.
Atomic Radius
• Radius is the distance from the center of the
nucleus to the “edge” of the electron cloud.
• Moving down a group, ATOMIC RADIUS
INCREASES
• Moving left to right across the periodic table
ATOMIC RADIUS DECREASES
• Each atom has another energy level, so the
atoms get bigger.
• Since electrons are being added to distant
shells away from the nucleus the valence
electrons are SHIELED by the inner shell
electrons.
Reactivity
• What makes an element reactive?
• An incomplete valence electron level.
• All atoms (except hydrogen) want to have 8
electrons in their very outermost energy level.
(This is called the octet rule).
• Atoms bond until this level is complete. Atoms
with few valence electrons lose them during
bonding forming cations (overall positive
charge)
• Atoms with 6, 7, or 8 valence electrons gain
electrons during bonding forming anions
(overall negative charge)
Reactivity
• We will be describing elements according
to their reactivity.
• Elements that are reactive bond easily
with other elements to make compounds.
• The most reactive metal is Francium (Fr).
The closer a metal is to Fr the more
reactive it is.
• The most reactive nonmetal is Fluorine
(F). The closer a nonmetal is to F the
more reactive it is.
Oxidation Number
• The oxidation number of an
element indicates the number of
electrons lost, gained, or shared
as a result of chemical bonding.
So we are really asking for the
charge.
Oxidation Number
Bonds
Metallic Bonds
• Metal and
metal bonded
Ionic Bonds
Covalent Bonds
• Metal and
nonmetal
bonded to
form a
compound
• Metal is giving
its valence
electron to the
nonmetal
• Example: NaCl
• Nonmetal and
nonmetal
bonded to
form a
compound
• The valence
electrons will
be shared
• Example: N2O2
Trends: Atomic Radius
• Moving left to right across the periodic
table ATOMIC RADIUS DECREASES
• More protons are being added to the
nucleus, valence electrons are strongly
attracted to the nucleus. Electrons are
also being added, but in the same shell
at about the same distance so there is
not much of a shielding effect.
Trends: Atomic Radius
• Moving down a group, ATOMIC
RADIUS INCREASES
• Each atom has another energy level,
so the atoms get bigger.
• Since electrons are being added to distant
shells away from the nucleus the valence
electrons are SHIELED by the inner shell
electrons.
Trends
Today: 03.14.14
• First you will complete the Element Wanted Ad
Project, you will sign up for elements.
• Then you will complete the Periodic Table
Search
• There are clues around the room to help you
complete the Periodic Table Search
• Each person will complete there OWN answer
sheet so that doesn’t mean traveling around
the room to look for answers.
• The last and final phase of today is a Periodic
Trends Assessment.
The Atom
All matter is made up of elements (e.g. carbon,
hydrogen, etc.).
The smallest part of an element is called an atom.
Atom of different elements contain different
numbers of protons.
Mass number = number of protons + number of neutrons
A
X
Z
Element symbol
Atomic number = number of protons
A
X
Z
A
= number of protons + number of neutrons
Z
= number of protons
A – Z = number of neutrons
Number of neutrons = Mass Number – Atomic Number
There are many types of uranium:
235
238
A
A
Z
Z
Number of
protons
Number of
neutrons
Number of
protons
Number of
neutrons
U
92
U
92
Most of the isotopes which occur naturally
are stable.
A few naturally occurring isotopes and all of
the man-made isotopes are unstable.
Unstable isotopes can become stable by
releasing different types of particles.
This process is called radioactive decay and
the elements which undergo this process are
called radioisotopes/radionuclides.
Radioactive Decay
Radioactive decay results in the emission
of either:
• an alpha particle (α),
• a beta particle (β),
• or a gamma ray(γ).
Radioactivity: Alpha
• two protons and two
neutrons
• charge +2e
• can travel a few
inches through air
• can be stopped by a
sheet of paper,
clothing.
Alpha Decay
A
A-4
X
Z
4
Y
He
+
Z-2
2
unstable atom
more stable atom
alpha particle
Radioactivity/Transmutation
Practice
A
X
Z
226
Ra
88
A-4
4
222
4
Y
+
Z-2
Rn
+
86
He
2
He
2
222
A
222
218
Rn
86
Rn
86
4
Y
He
+
Z
2
Po
+
84
4
He
2
Radioactivity: Beta
• Beta rays are made of
electrons traveling at
nearly the speed of light.
Beta rays are negatively
charged and can
penetrate a ½ centimeter
of aluminum.
•
•
•
electrons ejected from the
nucleus when neutrons decay
Beta particles have the same
charge and mass as "normal"
electrons.
Can be stopped by aluminum
foil or a block of wood.
Beta Decay
A
X
Z
218
Po
84
A
Y
+
Z+1
218
Rn
+
85
0
b
-1
0
b
-1
Radioactivity
• Gamma rays are the most powerful of the
three. The gamma rays have no mass and
no charge they are a true ray or wave.
Gamma rays are electro-magnetic waves
and are similar to X-rays. Gamma rays are
not made of any particles, they are pure
energy and that is why they can penetrate
more matter than other types of
radiations. Some gamma rays can
penetrate up to a meter of concrete.
Radioactivity: Gamma
• Gamma radiation g :
electromagnetic energy
that is released.
• Gamma rays are
electromagnetic waves.
• They have no mass.
• Gamma radiation has no
charge.
– Most Penetrating,
can be stopped by
1m thick concrete or
a several cm thick
sheet of lead.
Radiation
• Based on the fact that high-energy
gamma rays cause damage to
biological molecules
• Tumor cells are more susceptible than
normal cells
• Example: cobalt-60
• Gamma radiation can cure cancer, but
can also cause cancer
Chapter 17 Review
• Page 530
• 1-18
• Write question and YOUR
answer!!!
Ticket Out the Door
• Explain the differences between
alpha, beta, and gamma decay.
• If there were a radiation leak in the
room, how would you shield
yourself (what would you use as
protection?)
Half Life
• Half-life – time required for half
of the original sample of
radioactive nuclides to decay