Atomic Theory and the Periodic Table Review
What are the contributions of the following people to the atomic model? For those
that resulted in a revision to the model. Draw the model they proposed.
Democritus- originally named atom; atom model is solid homogenous sphere
Dalton- proposed the atomic theory, atom model is solid homogeneous sphere
Thomson- proved the existence of negative particles through work with
cathode ray tubes; atom model had negative particles embedded in positive
matrix (also called plum pudding model)
Rutherford- proved the existence of the nucleus with gold foil experiment;
atom model had positive particles in a nucleus surrounded by electron
Chadwick- discovered the neutron
Bohr- atom model had a nucleus of protons and neutrons surrounded by
electron in fixed orbits like planets orbiting the sun
Give the charge and location of each of the subatomic particles.
Particle
Charge
Location
Proton
__+_____
__nucleus__________
Neutron
__0_____
__nucleus__________
Electron
__-_____
_orbiting nucleus______
Define the following:
Atomic Number- number of protons in an atom
Mass Number- number of particles in the nucleus (protons + neutrons) in a
particular atom
Atomic Mass- average mass of all the naturally occurring isotopes of an
element according to their abundance
Isotope- atoms of the same element that differ in their number of protons
(and so also differ in their mass number)
Ion- atom with a charge because of the number of protons and electrons are
unequal
Calculate the number of protons, neutrons, and electrons of the following isotopes.
Isotope
# of Protons
# of Neutrons
# of Electrons
Hydrogen-3
1
2
1
Hydrogen-2
1
1
1
Calcium-40
20
20
20
Copper-63
29
34
29
Iodine-127
53
74
53
Barium-137
56
81
56
Write the nuclear symbol for each of the isotopes in the previous problem
_3H__
__2H __
___40Ca __
___63Cu __
___127I __
___137Ba ___
Positive ions are called _cations_____. They form when atoms __lose______
electrons. Negative ions are called _anions_______. They form when atoms
__gain______ electrons.
Calculate the number of protons, neutrons, and electrons of the following ions.
Ion
# of Protons
# of Neutrons
# of Electrons
37
Cl-
17
20
18
22
Na+
11
11
10
28
Mg+2
12
16
10
N-3
7
7
10
14
Calculate the average atomic mass of the following problems.
Silver (Ag) is found as two isotopes (silver-107 and silver-109). What is the
average atomic mass if the abundance of silver 107 is 51.86%?
107 x 0.5186 = 55.4902
109 x 0.4814 = 52.4726
55.4902 + 52.4726 = 107.96 amu
Iron has four isotopes (listed with their abundances below). Calculate the
average atomic mass.
Iron-54
5.90%
Iron-56
91.72%
Iron-57
2.10%
Iron-58
0.280%
54 x 0.0590 = 3.186
56 x 0.9172 = 51.3632
57 x 0.0210 = 1.197
58 x 0.00280 = 0.1624
3.68 + 3.666 + 35.232 + 2.695 = 55.91 amu
Who is the “father” of the period table?
Mendeleev
The modern periodic table has the elements arranged by their _atomic number___
forming columns called _groups or families___ and rows called _periods_______.
What group numbers are each of the following?
Alkali metals- 1
Alkaline earth metals- 2
Halogens- 17 (7A)
Nobel gases- 18 (8A)
Transition elements- 3-12
Determine whether the following elements are metals, metalloids, or nonmetals.
Ca
metal
Si
metalloid
Al
metal
Pb
metal
Ne
nonmetal
B
metalloid
List the seven diatomic elements. N, O, F, Cl, Br, I