# Atomic Theory Worksheet Historical Development of the modern model by yurtgc548

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```									                               Atomic Theory Worksheet

Historical Development of the modern model of the atom.

Draw below the model of the atom proposed be the following individuals

Dalton (1800)                Thompson (1897)                      Bohr (1913)

How did Thompson’s model differ from Dalton’s model?

The gold foil experiment resulted in two major discoveries which were made about the
structure of the atom. What were they?

1.

2.

How is an atomic spectra produced? Use the terms ground and excited state electrons in
your answer.

How does the Bohr model represent electrons around the central nucleus? Why (think of
spectra)?

The modern model of the atom is called the wave mechanical model. In the wave
mechanical model electrons are located around the nucleus based on the probability of
finding an electron in a certain area. These areas are called
a. shells      b. orbitals      c. rings      d. waves
Protons, neutrons, electrons

How many protons neutrons and electrons are in each of the following atoms?

Protons       Neutrons      Electrons

Carbon-12                           ______        ______        ___________

Chlorine-35                         ______        ______        ___________

Iron-55                             ______        ______        ___________

Carbon-14                           ______        ______        ___________

Chlorine-37                         ______        ______        ___________

How many total electrons are surrounding the following ions?

Na+       ___________               P-3    ___________

N-3       __________                Cr+6   ___________

H+        ___________               S-2    ___________

Average Atomic Mass/Isotopes

Define Isotope-

Define Atomic Mass-
Draw diagrams of the following nuclei to show how the following isotopes differ from
each other.

= Neutron        = Proton

lithium-6 and lithium-7

boron-10 and boron-11

Calculate the average atomic mass given the following isotopes and their percent
abundances.

Boron-10 19.78%; Boron-11 80.22%

Te-122 0.089%; Te-124 2.46%; Te-126 5.48%; Te-128 91.97%

There are three isotopes of element X. X-45, X-46, and X-48. If the atomic mass of
element X is 45.23 which isotope is most common? Why?
Electron configuration and lewis dot structures

Define valence electron-

How many energy levels and valence electrons are in the following electron
configurations?

Energy levels                valence electrons

2-8-2                           ___________                  ______________

1                               ___________                  ______________

2-8-18-4                        ___________                  ______________

2-8-18-14-1                     ___________                  ______________

Which of the following represents an excited state electron configuration?

2-8-8-1               2-8-7-1                   2-7-8-2                2-8-8-2

1-8-2                 2-8-2                     2                      2-8-5

Which elements are represented by the electron configurations above (all electron
configurations above are for neutral atoms)?

_________             _________                 _________              _________

________              _________                 __________             _________

Which electron configuration represents an atom of aluminum in the excited state?

2-7-4         2-8-3             1-8-5           2-8-7-1      2-8-1-3

Which electron configuration represents the ion Ca2+?

2-8-8-2       2-8-8             2-7-8-1         2-8-8-1      1-8-8-2
Draw the Lewis dot structure for elements 1-10

Selected Multiple Choice Questions

Atomic Theory

Matching

Match each item with the correct statement below.
a. proton                                      d. electron
b. nucleus                                     e. neutron
c. atom
____    1.   a positively charged subatomic particle
____    2.   a negatively charged subatomic particle
____    3.   a subatomic particle with no charge
____    4.   the central part of an atom, containing protons and neutrons

Match each item with the correct statement below.
a. mass number                                 d. atomic mass
b. atomic mass unit                            e. isotope
c. atomic number
____    5. atoms with the same number of protons, but different numbers of neutrons in the nucleus of an
atom
____    6. the total number of protons and neutrons in the nucleus of an atom
____    7. the number of protons in the nucleus of an element
____    8. the weighted average of the masses of the isotopes of an element

Multiple Choice
Identify the choice that best completes the statement or answers the question.

____  9. Which of the following is true about subatomic particles?
a. Electrons are negatively charged and are the heaviest subatomic particle.
b. Protons are positively charged and the lightest subatomic particle.
c. Neutrons have no charge and are the lightest subatomic particle.
d. The mass of a neutron nearly equals the mass of a proton.
____ 10. All atoms are ____.
a. positively charged, with the number of protons exceeding the number of electrons
b. negatively charged, with the number of electrons exceeding the number of protons
c. neutral, with the number of protons equaling the number of electrons
d. neutral, with the number of protons equaling the number of electrons, which is equal to the
number of neutrons
____ 11. The particles that are found in the nucleus of an atom are ____.
a. neutrons and electrons                         c. protons and neutrons
b. electrons only                                 d. protons and electrons
____ 12. As a consequence of the discovery of the nucleus by Rutherford, which model of the atom is
thought to be true?
a. Protons, electrons, and neutrons are evenly distributed throughout the volume of the atom.
b. The nucleus is made of protons, electrons, and neutrons.
c. Electrons are distributed around the nucleus and occupy almost all the volume of the atom.
d. The nucleus is made of electrons and protons.
____ 13. The atomic number of an element is the total number of which particles in the nucleus?
a. neutrons                                     c. electrons
b. protons                                      d. protons and electrons
____ 14. An element has an atomic number of 76. The number of protons and electrons in a neutral atom
of the element are ____.
a. 152 protons and 76 electrons                 c. 38 protons and 38 electrons
b. 76 protons and 0 electrons                   d. 76 protons and 76 electrons
____ 15. The sum of the protons and neutrons in an atom equals the ____.
a. atomic number                                c. atomic mass
b. nucleus number                               d. mass number
____ 16. What does the number 84 in the name krypton-84 represent?
a. the atomic number                            c. the sum of the protons and electrons
b. the mass number                              d. twice the number of protons
____ 17. All atoms of the same element have the same ____.
a. number of neutrons                           c. mass numbers
b. number of protons                            d. mass
____ 18. Isotopes of the same element have different ____.
a. numbers of neutrons                          c. numbers of electrons
b. numbers of protons                           d. atomic numbers
____ 19. The mass number of an element is equal to ____.
a. the total number of electrons in the nucleus
b. the total number of protons and neutrons in the nucleus
c. less than twice the atomic number
d. a constant number for the lighter elements
____ 20. Using the periodic table, determine the number of neutrons in O.
a. 4                                            c. 16
b. 8                                            d. 24
____ 21. If E is the symbol for an element, which two of the following symbols represent isotopes of the
same element?
1. E                     2. E                   3. E                   4. E

a. 1 and 2                                     c. 1 and 4
b. 3 and 4                                     d. 2 and 3
____ 22. Which of the following sets of symbols represents isotopes of the same element?
a.   J      J     J                            c.     M     M     M
b.   L      L      L                           d.     Q     Q      Q
____ 23. Which of the following isotopes has the same number of neutrons as phosphorus-31?
a.   P                                        c.    Si
b.   S                                        d.    Si
____ 24. Which of the following statements is NOT true?
a. Protons have a positive charge.
b. Electrons are negatively charged and have a mass of 1 amu.
c. The nucleus of an atom is positively charged.
d. Neutrons are located in the nucleus of an atom.
____ 25.   The atomic mass of an element is the ____.
a. total number of subatomic particles in its nucleus
b. weighted average of the masses of the isotopes of the element
c. total mass of the isotopes of the element
d. average of the mass number and the atomic number for the element
____ 26.   In the Bohr model of the atom, an electron in an orbit has a fixed ____.
a. position                                     c. energy
b. color                                        d. size
____ 27.   How does the energy of an electron change when the electron moves closer to the nucleus?
a. It decreases.                                c. It stays the same.
b. It increases.                                d. It doubles.
____ 28.   When an electron moves from a lower to a higher energy level, the electron ____.
a. does not change its energy
b. releases energy
c. absorbs energy
d. moves closer to the nucleus
____ 29.   What is the number of electrons in the outermost energy level of an oxygen atom?
a. 2                                            c. 6
b. 4                                            d. 8
____ 30.   Emission of light from an atom occurs when an electron ____.
a. drops from a higher to a lower energy level
b. jumps from a lower to a higher energy level
c. moves within its atomic orbital
d. falls into the nucleus
____ 31.   The atomic emission spectra of a sodium atom on Earth and of a sodium atom in the sun would
be ____.
a. the same
b. different from each other
c. the same as those of several other elements
d. the same as each other only in the ultraviolet range

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