13.
A -
A horizontal row is called a period, with elements listed in order of
increasing atomic numbers.
B -
A vertical column is a group, with elements that have similar properties.
14.
-Sodium (Na)
-Rubidium (Rb).
15.
A -
The noble gas family is located on the last row on the right side of the
periodic table.
B -
Noble gases are unreactive.
C -
Noble gases are chemically inert.
16.
A -
MgF2
B -
GaP
17.
In order to estimate the melting point of potassium (K), you would need to average
the melting points of the two elements: sodium (Na) and rubidium (Rb).
For
example:
98+39=137
137/2=68.5
Therefore,
the melting point of potassium (K) is about 68.5 degrees Celsius.
18.
In my opinion the boiling point of iodine is higher than the boiling point of
chlorine. Typically, if the atomic weight for an element is high and its
boiling point is even higher than those elements with low atomic weights.
Therefore, since iodine's atomic weight is 127 and chlorine's atomic weight is
35, I think that iodine has a higher boiling point.
19.
|
Element
Symbol
|
Number
of Protons
|
Number
of Neutrons
|
Number
of Electrons
|
|
C
|
6
|
6
|
6
|
|
C
|
6
|
7
|
6
|
|
Ca
|
20
|
21
|
20
|
|
Pt
|
78
|
117
|
78
|
|
U
|
92
|
146
|
92
|
20.
a. berylium: 4 protons, 4 or 5 neutrons, 4 electrons.
b. nitrogen: 7 protons, 7 or 8 neutrons, 7 electrons.
c. neon: 10 protons, 10 or 11 neutrons, 10 electrons.
21. This student is confused because an atom only gains or looses
electrons, the protons always stays the same. Therefore, in order to create a
lead atom with 2+, the atom had to
loose 2 electrons in order to become positive.
22.
A-
Carbon: 12
Calcium: 41
Clatinum: 195
Uranium: 238
B- Carbon has 2 isotopes in the periodic table of elements.
23. The mass number is not sufficient enough to excuse the claim of the
discovery of a new element. It would be more helpful to know the atomic weight
of the atomic number of the element opposed to the mass number.
24. The mass of an electron is much smaller than a proton or a neutron. It’s
about 1/2000 the mass of a proton or neutron.
25.
|
Isotope
Symbol
|
Mass
Number
|
Number
of Protons
|
Number
of Neutrons
|
|
Mg-24
|
24
|
12
|
12
|
|
Mg-25
|
25
|
12
|
13
|
|
Mg-26
|
26
|
12
|
14
|
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