Download Pennsylvania State Objectives: CHEM.A.2.1.1 Describe the

Pennsylvania State Objectives:
CHEM.A.2.1.1 Describe the evolution of atomic theory leading to the current model of the atom based on
the works of Dalton, Thomson, Rutherford, and Bohr.
CHEM.A.2.1.2 Differentiate between the mass number of an isotope and the average atomic mass of an
element.
CHEM.A.1.1.4 Relate the physical properties of matter to its atomic or molecular structure.
Daily Class Objectives:
 Create a display or written work illustrating how the atomic model has changed over time
 Describe and model the development of the atom over time
 Describe a cathode ray tube and how it relates to modern times
 Define the law of conservation of mass and constant composition
 Define, locate and determine the charge and mass of electrons, protons and neutrons
 Define and use atomic number
 Define isotopes
 Identify the atomic mass of an element
 Differentiate between atomic mass and mass number
 Write isotopic symbols
 Calculate mass number
 Determine the number of protons, electrons and neutrons in an atom
Vocabulary List (Vocab Quiz on Friday, 10/12)
Anode
Atom
Atomic Mass
Atomic Mass Unit (amu)
Atomic Number
Atomic Theory of Matter
Cathode
Cathode Ray
Cathode Ray Tube
Electron
Element
Isotope
Law of Conservation of Matter
Law of Constant Composition
Mass Number
Matter
Neutron
Nucleus
Proton
Radioactivity
The Development of the Atom
460-370 B.C.: Atomic Theory
Was Proposed by:
Model
The Concept:
According to this theory the Atom is:
-1782: Law of Conservation of Mass
Was Proposed by:
The Concept:
Question: If you begin a chemical reaction with 5 grams of reactant, how much product will
be formed at the end of the reaction?
-1799: Law of Constant Composition
Was Proposed by:
The Concept:
-1803: Dalton’s Atomic Theory
Was Proposed by:
The Model
The Concept:
-1897: The Electron
Was Proposed by:
Model
The Concept:
What is a cathode ray tube?
Today, the cathode ray tube can be found in the _____________________________.
What is an electron?
-1911: The Nuclear Model of the Atom (The Gold Foil Experiment)
Was Proposed by:
The Concept:
What is a proton?
What is the nucleus?
What is the neutron?
The Model
ATOMIC STRUCTURE
Particle
Proton
Location
Summary Chart of Subatomic Particles
Charge (C)
Simplified
Mass(g)
Charge
+1.602 x 10-19
1.673 x 10-24
Neutron
0
1.675 x 10-24
Electron
-1.602 x 10-19
9.109 x 10-28
Simplified
Relative
Mass (amu)
What is the Atomic Number of an element?
The atomic number also equals the __________________________________________ in an
atom because:
The atomic number is used to________________________________________
because:
The periodic table is arranged by _____________________________________.
What is the mass number of an element?
Mass number must be ___________________________, it cannot be found on the
___________________________.
To determine the mass number of an atom:
Mass Number =
So to determine the # of neutrons in an atom
Neutrons =
Complete the following by filling in for P, E, A and N:
A
P
E
M
A
N
t
a
o =
&
s =
+
m
s
i
c
#
#
Examples:
a) What is the atomic number of xenon?
b) How many protons does tungsten have?
c) How many electrons does rutherfordium have?
d) Which element has 98 protons?
e) Which element has 22 electrons?
f) What element has an atomic number of 44?
g) What is the mass number of an atom that has 21 protons and 23 neutrons? What element
is this?
h) What is the mass number of a carbon atom that has 8 neutrons?
i)
How many neutrons does an atom of Cesium with a mass number of 56 contain?
Example: Which of the following pairs represents isotopes of the same element?
a) an element with 4 protons & 3 electrons & an element with 5 protons & 3
electrons
b) an element with 4 protons & 4 electrons & an element with 4 protons and 3
electrons
ISOTOPES AND ATOMIC MASS
What is an isotope?
Give an example of an element’s isotopes:
Example: Which of the following pairs represents isotopes of the same element?
a) an element with 4 protons & 3 electrons & an element with 5 protons & 3
electrons
-ORb) an element with 4 protons & 4 electrons & an element with 4 protons and 3
electrons
What is the format for writing an isotopic symbol (the symbol for an isotope)?
What is the format for writing an isotopic name (the name of an isotope)?
Example: Write the isotopic symbol for the ion with
a) 21 protons, 24 neutrons, 18 electrons
b) 53 protons, 74 neutrons, 54 electrons
c) How many protons, electrons and neutrons are in an atom of
32
15P?
What is the atomic mass of an element?
amu =
Atomic mass is different from atomic mass because:
Atomic mass can be found on the ____________________________________.
Look at the table on Page 110 of the blue textbook. The atomic mass is always closest to the
isotope with the greatest abundance. Explain why, based on the fact that the atomic mass is
a “weighted” average.
ADVANCED LEVEL
How can you calculate the atomic mass of an element?
Atomic Mass =
Example: What is the atomic mass of an element if 98.89% of its
isotopes are carbon-12 and 1.11% of its isotopes are carbon-13?
Example:
a) What is the atomic mass of xenon?
b) What is the atomic mass of radium?
c) What element has an atomic mass of 260.1 amu.
d) Complete the following table.
Element
Name
Isotopic
Symbol
184
74
Atomic
Number
Mass
Number
Atomic
Mass
W
Number
of
Protons
Number
of
Neutrons
110
6
13
79.90
44
Number
of
Electrons