Download • Slip quiz - • Notes- Atoms - back to • Isotopes Notes (POGIL

27 Sept 2016
Agenda
• Slip quiz • Notes- Atoms - back to
• Isotopes Notes (POGIL)
• Homework
Slip Quiz - Based on the research
you did for homework
1. Name two scientists whose work had some
impact on the development of the Nuclear
Model of the atom.
2. When scientists use a phrase such as “The
Nuclear Model of the atom” what do they
mean by the use of the word “model” in this
context?
Slip Quiz - Based on the research
you did for homework
1. Name two scientists whose work had some
impact on the development of the Nuclear Model
of the atom.
Stoney - naming electrons
Roentgen - discovery X-rays
Curies -discovery of radioactivity
J. J. Thomson - discovery electrons
Rutherford, Geiger, Marsden - discovery nucleus
(protons)
Chadwick - discovery of neutrons
Model
2. When scientists use a phrase such as “The
Nuclear Model of the atom” what do they mean
by the use of the word “model” in this context?
Model - a conceptual, physical or mathematical
representation of a real phenomenon that is
difficult to observe directly. Used to explain
observations that have been made and predict
possible future observations.
https://www.learner.org/courses/essential/physic
alsci/session2/closer1.html
Atoms
1 nanometer (1
billionth of a meter)
-9
1 nm = 10 m
Fig. 1 STM topographic image of a single Co atom on Cu(111) shown in a light
shaded view. Current 1 nA, sample bias -10 mV, T = 2.3 K.
http://www.nist.gov/cnst/epg/atom_manipulation_stm.cfm
Powers of 10 http://www.youtube.com/watch?v=0fKBhvDjuy0
The Structure of the Atom
The Nuclear Atom Model
System (part of the universe under consideration and study)
https://www.youtube.com/watch?v=-FWxd78sOZ8
In Search of Giants Part 1 - The Building Blocks of Matter
• Atoms consist of a “cloud” of
fast moving negatively charged
electrons surrounding a tiny,
extremely dense (or massive, in
sense that it contains most of
the mass of the particle) nucleus
containing positively charged
protons and neutral neutrons
• The nucleus contains virtually all of
the atom’s mass, but occupies only
about one ten-thousandth the
volume of the atom
• The electrons are held within the
atom by their attraction to the
positively charged nucleus
The Structure of the Atom: Modern View cont.
The Strong Nuclear Force
protons are held together in the nucleus
by the strong nuclear force that acts over
short range (short distances) inside the
nucleus only and can overcome the
electrostatic repulsion between the positive
protons
(Note: There is accepted data from
experiments to support each of these
statements.)https://www.youtube.com/watch?v=kBgIMRV895w
The Structure of the Atom: Modern View cont.
Sub-subatomic particles
quarks (up, down, charm,
strange, top, bottom)
beyond scope of this course; for
the scale we need to understand
chemical reactions, nuclear
atom model is sufficient
Experimental Support for
Sub-atomic particles:
J. J. Thomsen and Discovery of the Electron
Cambridge Physics
Rutherford Gold Foil Experiment - Live
Demonstration (Backstage Science, Prof.
Kennedy) showing existence of nucleus
Properties of Subatomic Particles ( 4-1 p 97, 4-2 p 102)
Electron
Symbol
Location
Relative electrical
charge
Relative mass
(amu)
Actual mass (g)
e
Proton
-
in cloud
surrounding
the nucleus
1-
Neutron
+
n0
In the Nucleus of
the atom
In the Nucleus of
the atom
p
1+
0
1
1.007 276
1.008 665
1840
0.000 549
9.11 x 10 –28 1.673 x 10 – 24 1.675 x 10 – 24
Isotopes - Pogil
Are all atoms of an element alike?
Why?
The following activity will help you learn the
important structural characteristics of an
atom. How do we classify atoms? How does
the combination of subatomic particles affect
the mass and charge of an atom? What are
isotopes? This is just a sampling of what we
will address. Throughout this activity you will
want to keep both Model 1 and a periodic
table handy.
Model 1
Isotopes of Hydrogen
protons
1
1
1
neutrons
0
1
2
Model 1
Isotopes of Carbon
protons
6
6
6
neutrons
6
7
8
Model 1
Isotopes of Magnesium
protons
12
12
12
neutrons
12
13
14
1. Refer to Model 1. What subatomic particles do the
following symbols represent in the Atomic Diagrams?
electron
proton
neutron
Continue to check your responses.
3. Find the three elements shown in Model 1 on
your periodic table.
a. What whole number shown in Model 1 for each
element is also found on the periodic table for that
element? (edit the connecting line or write answer
below the word)
Hydrogen:- 1
Carbon:- 6 Magnesium:- 12
We are writing the number of protons for each
particular element.
3b. The whole number in each box of the
periodic table is the atomic number of the
element. What does the atomic number of an
element represent?
The atomic number of an element represents
the number of protons in the nucleus of an
atom of that element.
3c. Where is the atomic number located in the
isotope symbol ?
The lower left corner of the isotope symbol is
where the atomic number is written.
4. How many protons are in all chlorine (Cl)
atoms?
17 protons ; atomic number = 17
b) “I think that some chlorine atoms have 16
protons.” This is not correct because if an
atom has 16 protons, it has atomic number
16 and it would be called a sulfur atom. The
student has misunderstood the relationship
between the number of protons, the atomic
number and the name of an element.
VIP Question
5. a) How is the mass number determined?
Mass number is determined by adding the
number of protons and number of neutrons
together.
b) Why is this number called a “mass” number?
In an atom the particles that carry the majority of
the mass of the atom are the protons and the
neutrons. When you have counted them all up
you will have the approximate mass of that
atom in atomic mass units (amu).
6.
Atom I
Atom II
Number of
protons
5
9
Number of
neutrons
6
7
Mass
number
11
16
7. a) The mass number is in the upper left corner
of the isotope symbol.
b) The mass number is shown as a numeral
following the name of the atom, separated by a
hyphen. Examples:
carbon-12, hydrogen-3, magnesium-26
*Do not mix this up with what question 3 was
asking for, where you were looking up the
atomic number of the atom, the number of
protons
8.
Writing isotope symbols for the
atoms in question 6.
11
16
B
F
5
9
Atomic number 5, is Boron
Protons plus neutrons was 11, so this is the mass
number
Atomic number 9, is fluorine, mass # 16
9. Boron-11
Fluorine-16
10. Fill in the following table.
Isotope
symbol
40
K
19
Atomic
number
18
F
9
31
S
16
19
9
16
Mass number
40
18
31
Number of
protons
19
9
16
Number of
neutrons
40 - 19 =
21
18- 9 =
9
31- 16 =
15
11. a) All isotopes of a particular element have
the same atomic number.
For example, in Model 1 all the carbon isotopes
have an atomic number of 6, all the hydrogen
isotopes have an atomic number of 1 and all the
magnesium isotopes have an atomic number of
12.
b) All isotopes of an element do not have the
same mass number. The fact that isotopes have
different mass numbers is what makes them
different isotopes of that particular element.
For Example: Isotopes from Model 1 could be
carbon-12, carbon-13, and carbon-14 (which
shows us different mass number each time).
VIP to have a definition that is as
unambiguous as possible.
12. Isotope Definition:
Isotopes are atoms of the same
element so isotopes have the same
atomic number and isotopes have the
same number of protons as each other.
However, isotopes have different
numbers of neutrons (different mass
numbers) from each other.
Isotopes definition addendum 1
12. Please notice:
Sometimes an isotope will have the
same number of protons and neutrons
-Example Carbon-12 (6 protons, 6
neutrons)
But this does not have to be the case
Example carbon-14 (6 protons, 8
neutrons)
Isotopes definition addendum 2
12. Please notice:
We humans do not invent elements
and the number of protons and
neutrons - we’ve counted what we find
occurring in nature for each element.
We have found that elements exist
with patterns in the proportions of
their isotopes.
Homework
Complete Isotopes POGIL - Including Extension
Questions
Notes from Textbook, Chapter 4, The Structure of
the Atom, 4.1 Early Theories of Matter and 4.2
Subatomic Particles and the Nuclear Atom
Heads up - Unit test - Classification of Matter
and Atomic Structure - Wednesday October
5th.