Download Using your periodic table ppt (9/26-10/11) File

Periodic Table
An atom refresher
• Matter is anything that takes up space and has
mass.
• All matter is made of atoms
• Atoms are the building blocks of matter, sort of
how bricks are the building blocks of houses.
• Who contributed to the atomic theory from
ancient Greece to modern day?
Scientist that contributed to the
Atomic Theory include:
• Democritus – “Atomos”
• JJ Thomson – cathode ray tube, found
electrons, Plum Pudding model
• Ernest Rutherford – gold foil expt., found
nucleus as a positive center
• Neils Bohr – Bohr model with orbitals for
electrons around the nucleus, like a
planetary system
• Schrodinger – said e- act as particles
• Chadwick – found neutrons
• Heisenburg – pulled together all & said
there is an electron cloud model, quantum
Atom
• An atom has three parts:
• Proton = positive
• Neutron = no charge
• Electron = negative
• The proton & neutron are
found in the center of the
atom, a place called the
nucleus.
• The electrons orbit the
nucleus.
What are elements?
• Elements are the
alphabet to the language
of molecules.
• To make compounds,
you must have elements.
• Elements are made of
atoms. While the atoms
may have different
weights and organization,
they are all built in the
same way.
More about Elements..
• Elements are the building
blocks of all matter.
• The periodic table is a list of
all of the elements that can
build matter. It’s a little like
the alphabet of chemistry.
• The periodic table tells us
several things…
Families or groups
Alkali Metals
Alakaline Earth Metals
Transition Metals
Halogens
Noble or Inert Gases
Lanthinide Series
Actinide Series
What 2 main categories are on
the periodic table?
On your periodic table:
• Number the TALL Columns 1-8 because these
are called “representative elements” that the tall
column number is the same for how many
valence electrons exist on the outer most orbital
Periodic Table
Atomic Number:
Number of protons
and it is also the
same number of
electrons in the
element.
Symbol:
An abbreviation for
the element.
Elements Name
Atomic Mass/Weight:
Number of protons +
neutrons that exist in the
nucleus.
8
O
Oxygen
16
Using your periodic table
• Find the following using your periodic table:
Symbol
Na
Al
Cr
Bi
Ra
Name
Mass #
Atomic #
protons electrons
What is an isotope?
• Isotopes are two or more forms of the same
element that contain equal numbers of protons
but different numbers of neutrons in their nuclei
• Examples:
C-12
U-235
C-13
U-236
C-14
U-238
1. How many p+, e-, n0 exist in each isotope?
2. What is the element when it is
41
19
X?
Shorthand Notation:
Mass number
Symbol
Atomic number
35Cl
17
1. Write the shorthand notation for
Al
Cr
Bi
Ra
2. What do you use to tell the identity of
an element?
3. What changes to result in a charge on
an element?
4. What is an element with a charge
called?
ION is a charged element
1.Ions are a result of electrons being ________.
2. A positive charged element has ______
electrons & is called a ______.
3. A negative charged element has _____
electrons & is called a _____.
4. Draw the Bohr models of Na + Cl  NaCl and
show how electrons are transferred. Which part of
the reaction is a cation?______ Which is an
anion?_____
5. Which element gives up electrons when lithium
combines with fluorine to make lithium fluoride:
Li + F  LiF
Li+1
+ F-1  LiF
Atom Models
• There are two models of the atoms we will be
using in class.
• Bohr Model (orbitals around nucleus & show
valence electrons only in outer orbital)
• Lewis Dot Structure (only uses valence
electrons around the symbol & we will do these
at a later time)
Bohr Model
• The Bohr Model shows
all of the particles in the
atom.
• In the center is the
nucleus.
• In a circle around the
nucleus are the
electrons. Electrons
should have a minus
sign or an e.
e
Electrons have special rules….
• You can’t just shove all of the electrons into the
first orbit of an element.
• Electrons live in something called shells or
energy levels also referred to as orbitals.
• Only so many can be in any certain shell.
• The electrons in the outer most shell of any
element are called valance electrons.
Nucleus
1st shell
2nd shell
3rd shell
4th shell – if valence
orbital then it can only
hold a maximum of 8
electrons
NOTE: Only when there is another
orbital on the outside can the 3rd shell
hold up to 18 e-, otherwise if this is
the outermost orbital then it can only
hold 8 electrons to obey the octet rule!
So let’s try it….
• Draw the Bohr model for lithium:
3
Li
Lithium
7
QUIZ on Friday, I can:
(if absent be ready to take on Tuesday during Eagle Time)
• Interpret the arrangement of the Periodic Table,
including groups names and periods, for
orbitals & number of valence e-, & to know that
properties are similar for elements in a group
• Describe the structure of atoms, including the
masses, electrical charges, and locations of
protons, neutrons, and electrons
• Identify that protons determine an elements
identity and valence electrons determine its
chemical properties, including reactivity
• Describe the historical development of atomic
theory & periodic table – who did what.
On the Quiz, I can:
• Determine the number of protons, neutrons,
electrons, and charge of a neutral, ion, or
isotopic element by using isotope notation.
Who did what? (copy & Match them up)
• I used the Gold Foil
Experiment to discovered +
• Dimitri Mendeleev
charged nucleus & my model
• Democritus &
the “planetary system”
Aristotle
• I was the first to call the atom
• Niels Bohr
as atomos
• I worked with organizing the • John Dalton
periodic table using atomic
numbers.
•
I discovered the electron
using a cathode tube & my
atom model is called the
“plum pudding” model
• Henry Moseley
• Ernest Rutherford
• J.J. Thomson
Continue with Who did what?
• I organized the 1st
periodic table using
atomic masses.
• Dimitri Mendeleev
• Democritus &
Aristotle
• My atomic model helped
•
describe the orbits of
electrons, has been called •
the planetary model & is
•
still used today.
•
• I believed that atoms
could not be broken down •
Niels Bohr
John Dalton
Henry Moseley
Ernest Rutherford
J.J. Thomson
REVIEW the Periodic table:
1.How many electrons and protons are contained
in an atom of each of the following elements?
• a. arsenic
d. molibdenum
• b. gold
e. polonium
• c. fluorine
f. barium
2. Identify the atom containing the following
number of electrons (not ions).
• a. 34
d. 61
• b. 5
e. 94
• c. 31
3. Identify the atom containing the following
number of protons.
• a. 74
d. 70
• b. 20
e. 93
• c. 49
4. Add the number of orbitals and valence
electrons that exist on the elements in question 3.
5. Atoms of which element contain 18 protons and
18 electrons?
6. Describe the subatomic particles comprising an
isotope of zirconium-94.
7. An atom of a certain element has a mass
number of 112 and is known to contain 64
neutrons. Identify the atom and determine the
number of electrons and protons the atom
contains.
8. A neutral atom has 78 electrons and a mass
number of 198. Identify the atom and determine
the number of protons and neutrons in its nucleus.
How to solve for ATOMIC MASS:
• Atomic mass Scientists have established a
standard for the measurement of atomic mass
by assigning the carbon-12 atom a mass of 12
atomic mass units (amu). Thus, 1 amu is
equal to 1/12 the mass of a carbon-12 atom.
• The number at the bottom of each square in the
periodic table is the atomic mass of that
element in amu. A scan of the periodic table will
immediately tell you that the atomic masses of
many elements are not whole numbers. The
reason for this is that many elements occur in
nature as a mixture of isotopes—isotopes with
different masses.
ATOMIC MASS
• The atomic mass of an element given in the
table is a weighted average of the atomic
masses of the naturally occurring isotopes of
the element. This weighted average takes into
account the mass and abundance of each of
the isotopes.
Example Problem:
Calculating Atomic Mass
Copper exists as a mixture of two isotopes.
• Cu-63 makes up 69.17% of copper atoms with an
atomic mass of Cu-63 is 62.930 amu
• Cu-65 constitutes the remaining 30.83% of copper
atoms with an atomic mass of 64.928 amu
STEPS to SOLVE by:
1)Put the % value into a decimal value
2)Mass contribution = mass of isotope X abundance
of isotope put in a decimal value
3)The average atomic mass or amu of the element is
the sum of the mass contributions of each isotope
Review “average atomic mass”
Ex. Sample of cesium is 75% of 133 amu, 20% of
132 amu, and 5% of 134, what is the average atomic
mass?
Answer:
.75 X 133 = 99.75
.20 X 132 = 26.4
.05 X 134 = _6.7__
Total +
132.85 amu or average
atomic mass
127
126
128
1.
80%
I, 17%
I, 3%
I
2.
50% 197Au, 50% 198Au
3.
15% 55Fe, 85% 56Fe
4.
99% 1H, 0.8% 2H, 0.2% 3H
Review “average atomic mass”
5. The following table shows the five isotopes of germanium
found in nature, the abundance of each isotope, and the
atomic mass of each isotope.
Calculate the average atomic mass of germanium.
• Isotope
Abundance (%)
Atomic Mass (amu)
• Germanium-70
21.23 %
69.924
• Germanium-72
27.66 %
71.922
• Germanium-73
7.73 %
72.923
• Germanium-74
35.94 %
73.921
• Germanium-76
7.44 %
75.921
6. Gallium occurs in nature as a mixture of two
isotopes. They are Ga-69 with a 60.108%
abundance and a mass of 68.926 amu and Ga-71
with a 39.892% abundance and an atomic mass of
70.925. Calculate the atomic mass of gallium.
7. The atomic mass of bromine given in the periodic
table is 79.904 amu, which is very close to 80 amu.
Use a reference book to find the percent of Br-80 in
naturally occurring bromine. Explain the value of the
atomic mass of bromine from the data you find.
8. The element chlorine occurs in nature as a
mixture of two isotopes. Chlorine-35 has an atomic
mass of 34.969 amu and makes up 75.77% of
chlorine atoms. Chlorine-37 atoms make up the
remaining 24.23% of all chlorine. Use the average
atomic mass of chlorine from the periodic table to
calculate the atomic mass of Cl-37 atoms.