Atomic Structure Unit Test Version 2
1-
The table below gives the atomic mass and the abundance of the two naturally
occurring isotopes of chlorine.
Naturally Occuring Isotopes of Chlorine
Isotope
Atomic Mass of the Isotope Natural Abundance
(u)
(%)
35
Cl
Cl
37
34.97
36.97
75.76
24.24
The numerical setup used to calculate the atomic mass of the element chlorine
is
(34.97 u)(0.7576) + (36.97 u)(0.2424) or (34.97 u)(75.76) + (36.97 u)(24.24)
100
100
2-
The energy and the most probable location of an electron in the third shell of an
atom is compared to the energy and the most probable location of an electron in
the first shell of the same atom as follow:
Compared to the energy and location of an electron in the first shell the
electron in the third shell has more energy and is farther from the nucleus.
3-
The overall charge of an ion that has 12 protons, 10 electrons, and 14 neutrons is
2+ because there are two more protons (12 having positive charge) than the
electrons (10 having negative charge). 12+-10- = 2+
4-
The subatomic particles found in the nucleus of an atom of Beryllium (like other
atoms) are neutrons and protons.
5-
6-
7-
According to the wave-mechanical model an orbital is defined as the most
probable location of electrons.
The symbol for an atom containing 20 protons and 22 neutrons is 20Ca because
the lower number is the atomic number representing the number of protons and
the top number, the mass number, is the sum of protons and neutrons. The number
of neutron is calculted by subtracting the atomic number (the number of proton)
from the mass number (the sum of protons and neutrons).
42
The electron configuration which represents an atom in the excited state is
1s2, 2s2, 2p5, 3s2
Because there are total 11 electrons and the atom is sodium, the
given electronic cofiguration is different than 2,8, 1 (the one given under the symbol
of sodium in the periodic table). Furthermore, the given configurations clearly
shows that one electron from 2P orbital on the 2nd energy level has jumped to the
3S orbital on the 3rd principal energy level. Hence, proving that this is the excited
electronic configuration.
8-
The true statement about a proton and an electron is that they have different masses
and different charges [ a proton is positively charged and has mass of 1 amu. On
the other hand, an electron is negatively charged and has mass of zero (or
negligible].
9-
As the result of the gold foil experiment it was concluded about the structure of an
atom that positively charged nucleus is surrounded by mostly empty space.
10-
The atomic mass of Magnesium (like most of the atoms) is the weighted average
of the atomic masses of all of the naturally occurring isotopes of Mg.
11-
An atom is electrically neutral when the number of protons (positively charged
particles) equals the number of electrons (negatively charged particles).
12-
The orbital notation which correctly represents the outermost principal energy
level of oxygen in the ground state is
Because right under the symbol of oxygen in the periodic table the written
electronic configuration of oxygen is 2,6, which means the outermost
principal energy level of oxygen has 6 electrons.
13-
The charge of an electron and the charge of a proton is described as
follow: An electron has a charge of -1, and a proton has a charge of +1.
14-
The elements arranged in order of increasing atomic mass are Cl, K, Ar.
15-
In the bright-line spectra of three elements and the spectrum of a mixture formed
from at least two of the elements mentioned above shows that the mixture contains
E and D only because when we project the lines of the mixture spectrum they
coincide with the spectral lines of E and D only.
16-
The electron configuration which represents the electrons in an atom of Ga in an
excited state is 2-8-17-4 because this electronic configuration is different from
the electonic configuration given below the symbol of Ga (atomic number 31)
in the periodic table. The above given electronic configuration shows that one
electon jumped from 3rd principal energy level to 4th principal energy level and
that’s why this arrangement is an excited state for Ga.
17-
The numbers of protons and neutrons in each of four different atoms are shown in
the table below.
Only two atoms, D and E, have the same number of protons but different number
of neutrons and therefore, are isotopes of the same element. Atom A with 8 protons
is oxygen, atoms D and E with 9 protons are atoms of the same element flourine,
and atom G with 10 protons is neon. It is evident that only atom D and E are isotopes
of the same elemnt because they have the same number of protons but different
number of neutrons.
18-
The two notations that represent different isotopes of the same element must have
the same number of protons (atomic number).
and
are isotopes
of Beryllium because both the notations have the same atomic number 4 (4
protons in the nucleus).
4
2
19-
The atomic mass unit (amu) is defined as exactly 1/12 of the mass of an atom
of Carbon-12, which can also be written as 126C
20-
The table below gives information about the nucleus of each of the four atoms.
In this table, only two different elements with atomic number (number of protons)
6 and 7 are given. The atom with 6 protons is carbon and the atom with 7 protons
is nitrogen. The number of protons is the identity of an atom/element. Therefore,
there are only two elements (2 atoms of Carbon and 2 atoms of Nitrogen).