Download Review

Academic Chemistry – Chapter 3
Unit 3
Structure of the Atom
Vocabulary:
Law of Conservation of Mass (66)
Law of Definite Proportions (66)
Law of Multiple Proportions (66)
Weighted Average (79)
Nuclear Forces (74)
Atomic Number (75)
Isotope (76)
Atom (70)
Mass Number (76)
Atomic Mass Unit (78)
Average Atomic Mass (79)
Textbook Readings and Homework:
R&O 3 – 1
SR 3-1
R&O 3 – 2
SR 3-2
R&O 3-3
SR 3-3
EOC
The Atom: From Philosophical Idea to Scientific Theory
Problems # 1 – 3
The Structure of the Atom
Problems # 2ac - 4
Counting Atoms
Problems # 1ab, 2 ac, 3a
Problems # 5, 6, 7, 8, 9, 11, 19, 20
p 65 – 69
p 69
p 70 – 74
p 74
p 75 – 80
p85
p 87
Objectives:
By the end of this unit you should…
1. Explain the law of conversation of mass, the law of definite proportions, and the law of multiple
proportions.
2. Summarize the five essential points of Dalton’s atomic theory.
3. Explain the relationship between Dalton’s atomic theory and the law of conversation of mass, the
law of definite proportions, and the law of multiple proportions.
4. Summarize the observed properties of cathode rays that led to the discovery of the electron.
5. Summarize the experiment carried out by Rutherford that led to the discovery of the nucleus.
6. List the properties of protons, neutrons, and electrons.
7. Define atom.
8. Explain what isotopes are.
9. Define atomic number and mass number, and describe how they apply to isotopes.
10. Given the identify of an isotope, determine the number of protons, neutrons, and electrons
Activities and Labs:
1.
2.
3.
4.
5.
Demonstration of the Think Tube
Demonstration of Cathode Ray Tube
Lab: Black Box
Lab: Rutherford’s Experiment
Lab: Isotopes of Pennium
1
Law of Conservation of Mass
PART A – CHEMICAL LAWS
Fill in the blanks
In the 1790's, the study of matter was ______________________________ by a new emphasis on the
___________________________ analysis of chemical reactions. This lead to the discovery of several
basic ___________.
a. The Law of Conservation of Mass - Mass is neither ____________________ nor
________________ during ordinary chemical or physical __________________________.
b. The Law of Definite Proportions - A chemical compound contains the same
__________________ in exactly the same _________________________ by ____________
regardless of the size of the sample or _________________ of the compound.
c. The Law of Multiple Proportions - If two or more different compounds are composed of
the ______________ two elements, then the ratio of the masses of the second element combined with a
certain mass of the ______________ __________________ is always a ratio of small
_______________________ numbers. An example of this is the elements carbon and oxygen forming
the two compounds carbon ________________________ and
carbon____________________________.
1. Water, H2O, is the universal solvent. Hydrogen peroxide, H2O2, is a poison. How do water and
hydrogen peroxide illustrate the law of multiple proportions?
2. Carbon reacts with oxygen to produce carbon dioxide (CO2) in a chemical reaction. What mass of
carbon dioxide would be produced if 24 g of carbon react completely with 64 g of oxygen? Which
law is illustrated here?
3. In a lab experiment, a student discovers that his sample of table salt (NaCl) is 39.34% by mass
sodium (Na) and 60.66% by mass chlorine (Cl). What is the percent sodium by mass of Na in the
table salt in your saltshaker at home? What law is illustrated here?
2
Dalton's Atomic Theory
1. John Dalton reasoned that elements were composed of ______________ and that only
______________ numbers of atoms can combine to form __________________. His Atomic Theory
can be summed up by the following statements:
a. All matter is composed of extremely ______________ particles called ___________.
b. Atoms of a given element are ______________________ in size, mass and other properties; atoms of
different elements ________________ in size, mass, and other properties
c. Atoms cannot be ____________________, _____________________ or __________________.
d. Atoms of different elements combine in simple _________________-number ratios to form chemical
_____________________________.
e. In chemical reactions, atoms are combined, _____________________, or rearranged.
JJ Thompson’s Atomic Theory
2.
What is a cathode ray?__________________________________________
____________________________________________________________________________
3.
Who “discovered” the electron and when?
__________________________________________________________________
4.
Sketch a cathode-ray tube and label it with the following parts: Partially evacuated glass vessel,
electrically charged plates, cathode, anode, magnet, electron path, fluorescent screen, high
voltage source. Explain how it works.
5.
Investigators noticed that when current was passed through a ___________________-ray tube, the
surface of the tube directly opposite the _______________________ glowed. These rays could move
a ___________________ wheel and were deflected away from a ___________________ charged
object.
3
6.
JJ Thomson concluded that all cathode rays are composed of identical ___________________
charged particles, which were later named ____________________________.
7.
Cathode-ray experiments provided evidence that atoms are _________________________ and
that one of the atom's basic constituents was the _____________________-charged electron.
8.
Two other inferences were made about atomic structure:
a.
Because atoms are electrically _____________________, they must contain a
_________________ charge to balance the negative electrons.
b.
Because electrons have so much less ______________ than atoms, atoms must contain
other particles that account for most of the _______________.
Rutherford’s Atomic Theory
1.
What significant experiment is Rutherford known for?
2.
Rutherford’s gold foil experiment led to the downfall of the “plum pudding” model. Explain
the gold foil experiment and its results. Include a schematic
The Modern Atomic Theory
1. What did Chadwick discover?
2. What did Bohr discover?
3. What paths do electrons follow in the Bohr model?
4
The modern atom
1.
Define atom.
2.
Define proton. What is its mass and charge?
3.
Define neutron. What is its mass and charge?
4.
Define electron. What is its mass and charge?
5.
Atoms are electrically neutral because they contain equal numbers of ______________________ and
_____________________________. The neutron is electrically_______________________
6.
The number of _____________________ in an atom's nucleus determines that atom's identity
7.
Generally, particles that have the same electric charge __________________ one another.
8.
However, when two protons are extremely __________________ to each other, there is a strong
_____________________ between them. Similar attraction exists when ___________________ are
very close to each other, or when protons and _____________________ are very close together.
9.
Complete the following table:
Particle
Mass
Charge
Location
Proton
Neutron
Electron
Atomic Number
1. Atoms of different elements have different numbers of _____________________. The atomic
number (___) of an element is the number of ____________________ in the nucleus of that
element.
2. The atomic number identifies an ______________________.
5
Isotopes
1. All hydrogen atoms contain one _____________________. However, like many naturally occurring
elements, hydrogen can contain different numbers of _______________________. _________ types
of hydrogen atoms are known.
a. The most common type is sometimes called _______________________. Its nucleus has _______
proton only, and has one __________________ moving about it.
b. Another form is called _________________________. Each atom has a nucleus containing one
__________________ and one ____________________.
c. The third form of hydrogen is _____________________, which is radioactive. Each atom contains
one ___________________, two _____________________, and one electron.
2. Isotopes are atoms of the same _____________________ that have different _____________. The
isotopes of an element all have the same number of ___________________ and
_____________________ but different numbers of ______________________. Most of the
elements consist of ___________________ of isotopes.
Mass Number
1. Identifying an isotope requires knowing both the name or atomic ___________________ of the
element and the ___________ of the isotope.
2. Mass number is the total number of _________________ and __________________ in the
nucleus of an isotope.
Designating Isotopes
1. Isotopes are usually identified by specifying their _____________ ___________________.
There are two methods for specifying isotopes.
2. Write the hyphen notation for an atom of potassium with a mass of 40: ________________
3. Write the nuclear symbol notation for an atom of fluorine with a mass of 19:_______
4. The number of neutrons is found by subtracting the ________________ number from the
__________number.
5. An atom has 10 neutrons and a mass number of 19. Which of the following is an isotope of
this element?
F
20
Ne
20
Ne
19
K
39
Cu
65
6. Nuclide is a general term for any _____________________ of any element.
6
Complete the following chart:
Element
Ba -137
Atomic #
Mass #
56
137
Protons
Neutrons
8
8
Fe+3
108
47
14
7
# of
Charge of ion
Electrons
or atom
26
30
Ag
N 3
14
7
207
82
79
118
2. Define ion, and give two examples from the table above.
3. Define isotope, and give two examples from the table above.
Average Atomic Masses of Elements
1. The ____________________________ of each isotope in the _______________________
occurring element on Earth is nearly always the ____________, no matter where the element is
_________________.
2. Average atomic mass is the _______________________ _____________________ of the atomic
masses of the naturally occurring isotopes of an element.
7
AVERAGE ATOMIC MASS
1. How is it possible for the "average" family in America to have 2.3 children?
2. Boron consists of two isotopes in nature. 81% of all boron atoms have a mass number of 11,
and the rest of them have a mass number of 10. Calculate the average atomic mass of boron.
3. An imaginary element called Cafetorium (Ct) is discovered to have three isotopes. 25% are Ct288, 66% are Ct-290, and the rest are Ct-291. What would be the atomic mass of Cafetorium?
4. Calculate the average atomic mass of iron if its abundance in nature is 15% iron-55 and 85%
iron-56.
5. What is the average atomic mass of silicon if 92.21 % of its atoms have a mass of 27.977 amu,
4.07 % have a mass of 28.976 amu, and 3.09 % have a mass of 29.974 amu?
6. Calculate the average atomic mass of silver if 13 out of 25 atoms are silver-107 and 12 out of
25 atoms are silver-109.
7. Boron has three naturally occurring isotopes: boron-10, boron-11, and boron-12. If the average
atomic mass of boron is 10.811 amu, which isotope is the most abundant? How do you know?
8
Directions: Put the number of the definition from the list below into the square with the appropriate
term. Check your answers by adding the numbers to see if all the sums of all rows, both across and
down add up to the same number, the Magic #.
Democritus
Dalton
Thomson
Chadwick
Total
_____
_____
_____
______
_____
Rutherford
Proton
Atom
Bohr
_____
_____
_____
_____
Wave Model
Neutron
Nucleus
Alpha particle
_____
_____
_____
_____
Electron
Model
Energy levels
Electron cloud
_____
______
_____
_____
_____
_____
______
Total _____
Magic Number ______
1. Represented by a symbol; all are found on the Periodic Table
2. Made a mental model of the atom; Greek philosopher
3. Used by Rutherford in his experiment; made of two protons and two neutrons
4. The paths in which electrons circle the nucleus according to the Bohr model
5. The positive particle in the nucleus of an atom
6. The tiny positive core of an atom; contains protons and neutrons
7. Formed the atomic theory model of the atom; English schoolteacher
8. Discovered the nucleus using his gold foil experiment
9. Current explanation of where electrons might be found in the atom
10. Used by scientists to explain something we can not see or understand
11. The smallest particle of an element that has the properties of that element
12. Discovered the neutron
13. Current model of the atom; proposed by Schrodinger
14. Mass of protons and neutrons
15. Developed the model of the atom in which electrons orbit the nucleus in energy levels
16. The negative particle that circles the nucleus
17. The neutral particle in the nucleus of an atom
18. Proposed the “plum-pudding” model of the atom; discovered the electron
9
_____
_____
_____
Review
1. What information about the subatomic makeup of an atom is given by the following?
a) atomic number
b) mass number
c) mass number + atomic number
d) mass number – atomic number
2. Determine the number of protons, neutrons, and electrons present in each of the following
atoms.
a) 28Si
14
b)
c)
161
79
40
Au
Ar
18
d)
64
Cu
29
e)
39
K
19
f)
133
Cs
55
3.
Identify atoms that are isotopes in each of the following sets of four atoms.
a) 80X, 82X, 81X
35
b)
c)
19
35
19
X,
17
X,
9
10
9
23
24
25
X,
11
d)
36
70
X,
31
X,
11
70
X,
32
20
X,
X
8
X
11
70
33
X,
70
X
34
4. Write the symbol, atomic number and atomic mass for the atoms with the following.
b) Contains 15 neutrons and 13 protons.
c) Atomic number is 41.
d) Contains 33 electrons and 42 neutrons.
e) Iron contains 84 subatomic particles.
f) Rubidium that contains 87 neutrons.
10
Vocabulary Word
Dictionary definition –
full sentence
In your own words
Atom (70)
Atomic Mass Unit (78)
Atomic Number (75)
Average Atomic Mass (79)
Isotope (76)
Law of Conservation of Mass (66)
Law of Definite Proportions (66)
Law of Multiple Proportions (66)
Mass Number (76)
Nuclear Forces (74)
Weighted Average (79)
11
Example
Non Example