Chemistry 1
West Linn High School
Unit 2 Packet and Goals
Name:_________________________________
Period:_________
Unit 2 – Atomic Structure and Nuclear Chemistry
Unit Goals:
As you work through this unit, you should be able to:
1. describe Dalton’s atomic theory and compare to our modern understanding of the atom (4.1)
2. distinguish among protons, electrons, and neutrons in terms of mass and charge. (4.2)
3. describe the structure of the atom. (4.2)
4. explain why isotopes differ and why atomic masses are not whole numbers. (4.3)
5. understand how atomic mass is calculated. (4.3)
6. describe the three main types of nuclear radiation (25.1)
7. complete transmutation nuclear equations (25.2)
8. distinguish fission reactions from fusion reactions (25.3)
Reading:
Chapter 4: (pp 102-124) Sections 4.1 – 4.3
Chapter 25: (pp 874-893) Sections 25.1-25.3
Key Terms:
atom, electrons, neutrons, nucleus, protons, atomic number, mass number, atomic mass, atomic mass unit, isotope, radioisotope,
alpha, beta, gamma, transmutation, fission, fusion, Dalton’s atomic theory, Plum Pudding Model, Rutherford’s Gold Foil Experiment
Homework:
HW 1
Classwork and Labs
Description
Atomic Structure Worksheet
Goals
1-3
Score
Unit 2 Note Packet
Indirect Measurement Activity
HW 2
Isotopes Worksheet
4-5
Vegium Lab
Nuclear Chem Simulations Activity
HW 3
Nuclear Chemistry Worksheet
6-8
Unit 2 Exam
Chapter 4
4.1 Defining the Atom
Early Models of the Atom: Page 102
A. Define an Atom
B. Democritus’s Atomic Philosophy
C. Dalton’s Atomic Theory
1.
2.
3.
4.
All elements are composed of tiny indivisible particles called atoms.
Atoms of the same element are identical. Atoms of different elements are different.
Atoms combine in simple whole number ratios.
Atoms of one element are never changed to atoms of another element during chemical
reactions.
Sizing up the Atom: Page 103
A. What instruments can be used to observe individual atoms?
4.2 Structure of the Nuclear Atom
Subatomic Particles: Page 105
A. What are the 3 kinds of subatomic particles?
Electrons:
• J.J. Thomson – 1897
• Discovered the electron using
a cathode ray tube (CRT)
• Negatively charged particles
Protons:
• E. Goldstein – 1886
• Discovered the proton by
careful observations of
another ray in the Cathode
Ray tube
• Positively charged particles
Neutrons:
• James Chadwick – 1932
• Discovers the neutron
• Neutrons are the “glue” that holds the nucleus of the atom together.
Atomic Charges
“Plum Pudding” Model
• Electrons evenly distributed in an atom filled
with uniform positive chare
• First Atomic Model
The Atomic Nucleus: Page 107
A. Summary of the “Gold Foil” experiment performed by Rutherford (page 108)
B. The Rutherford Atomic Model (page 108-109)
1. An atom is mostly space.
2. There is a nucleus in the middle of the atom containing the protons
3. The electrons orbit a large distance away from the nucleus.
4. Proposes a “Solar System” or “Orbital” model of the atom
Atomic Particle Summary
Name
Symbol
Charge
Electron
proton
neutron
4.3 Distinguishing Among Atoms
Atomic Number and Mass Number: Page 112
Define Atomic Number:
Define Mass Number:
How to find the number of Neutrons in a Nucleus:
Mass
(amu)
Sample Problem 4.2 (page 114)
How many protons, electrons, and neutrons are in each atom?
9
23
20
a. 4 Be
b. 10
c. 11
Na
Ne
Example Problems (page 114)
18
19
Isotopes: Page 114
Define: Isotope
Atomic mass unit:
– Unit of mass for atomic nuclei
– 1 amu = 1/12 the mass of Carbon12
Isotopic Symbols:
Atomic Mass:
– Weighted average mass of all the
naturally occurring isotopes in a
sample of an element
Atomic Mass: Page 116
Sample Problem 4.5 (page 119)
Element X has two naturally occurring isotopes. The isotope with a mass of 10.012 amu has a relative
abundance of 19.91%. The isotope with a mass of 11.009 amu has a relative abundance of 80.09%.
Calculate the atomic mass of element X.
Example Problems: Page 119
24
25
Chapter 25
Regular Chemistry vs. Nuclear Chemistry
Regular Chemistry
• Deals with the arrangement of atoms to
form compounds
• Never about the changing of the nucleus
• Elements NEVER change to other Elements
25.1
Nuclear Chemistry
• Deals with the decay of unstable isotopes
to form a stable nucleus
• About the changing of the nucleus
• Elements CAN change to other Elements
Nuclear Radiation
Define:
Radiation
Property
Composition
Alpha
Beta
Alpha Particle
Beta Particle
(helium nucleus)
(electron)
Symbol
Charge
Radioactive Decay
Mass (amu)
Penetrating
Power
Radioisotope
Alpha Radiation (page 877)
Example
Gamma Radiation (page 879)
Examples
Beta Radiation (page 878)
Example
Gamma
High-Energy
Radiation
25.2 Nuclear Transformations
What holds the nucleus together?
Strong Nuclear Force
– Short range, attractive force that acts among nuclear particles
– Neutrons and Protons attract one another!
– Much stronger than electrical or gravitational force
Electromagnetic Force
– Repulsive force between protons. Tries to pull the nucleus apart.
Stable Nucleus
– Correct balance of Strong Nuclear & Electromagnetic Forces
– Correct p+ to n ratio
– MOST ATOMS ARE STABLE!!
Band of Stability
Most common transformation particles
Radiation Name
Alpha particle
Beta particle
Gamma radiation
Positron
Neutron
Proton
Symbol & Iso. Notation
Charge
Mass
Nuclear Stabilization Equations
 Alpha emission:
Uranium-238
Transformation Examples
Silicon-27  ______ + β
 Beta emission:
Carbon-14
Bismuth-214  _____ + α
 Positron emission:
Oxygen-15
Aluminum-27 + α  Silicon-30 + ____
 Neutron emission:
Silver-107
25.3 Fission and Fusion
Define Fission
– Large nucleus breaking down into
smaller nuclei
Define Fusion
– Smaller nuclei combining to larger
nucleus
Journal and Warm-up:
Remember to record; date and question for each warm-up problem. Show all work and edits to correct.
Journal and Warm-up:
Remember to record; date and question for each warm-up problem. Show all work and edits to correct.