Download Chapter 7 Periodic Properties of the Elements

CHE141
Chapter 7
Chapter 7
Periodic Properties of the Elements
1. Elements in the modern version of the periodic table are arranged in order of
increasing __________.
(a). oxidation number
(b). atomic mass
(c). average atomic mass
(d).atomic number
Explanation: The older version of the periodic table had the elements arranged in
order of increasing atomic mass, but the modern version of the periodic table is based
on the increasing order of atomic number.
2. The first ionization energies of the elements __________ as you go from left to right
across a period of the periodic table, and __________ as you go from the bottom to
the top of a group in the table.
(a). increase, increase
(b). increase, decrease
(c). decrease, increase
(d). decrease, decrease
Explanation: The ionization energies (IE s) of elements increase to the right in a row
since larger amounts of energy need to be supplied to remove an electron. The
elements become more non-metallic making it harder to remove an electron.
3. The __________ have the most negative electron affinities
(a). alkaline earth metals
(b). alkali metals
(c). halogens
(d). transition metals
Explanation: The electron affinity of an element is defined as the energy change that
occurs when an electron is added to a gaseous atom. The halogens have the most
negative electron affinities indicating that they are most comfortable accepting an
electron. The formation of an anion essentially gives the halogen atom the electron
configuration of the nearest noble gas. The negative sign here indicates that the
addition of an electron to the halogens results in energy being released by the halogen
atom.
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4. Element M reacts with chlorine to form a compound with the formula MCl2. Element
M is more reactive than magnesium and has a smaller radius than barium. This
element is __________.
(a). Sr
(b). K
(c). Na
(d). Ra
Explanation: The formula of the compound MCl2 indicates that M must have 2+
charges on it and it must be an alkaline-earth metal. Element reactivity and atomic
radius typically increase down the group, which means that the element could be Ca
or Sr. Since Sr is the only option that fits the answer is Sr.
5. The oxide of which element below can react with hydrochloric acid?
(a). sulfur
(b). selenium
(c). sodium
(d). nitrogen
Explanation: For the oxide to react with hydrochloric acid, it must be a basic oxide.
Only metals form basic oxides and out of the options provided, sodium is the only
metal.
6. Metals can be __________ at room temperature.
(a). liquid only
(b). solid only
(c). solid or liquid
(d). solid, liquid, or gas
Explanation: Most metals are solids at room temperature with one prominent
exception, which is mercury.
7. Na reacts with element X to form an ionic compound with the formula Na3X. Ca will
react with X to form __________.
(a). CaX2
(b). CaX
(c). Ca2X3
(d).Ca3X2
Explanation: The element X must have 3 negative charges for it to form the
compound Na3X, since each Ca has 2 positive charges, the formula of the compound
formed by the reaction of Ca and X would have to be Ca3X2.
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Chapter 7
8. What is the coefficient of M when the following equation is completed and balanced
if M is an alkali metal?
M (s) + H2O (1)
(a). 1
(b).2
(c). 3
(d). 0
Explanation: For this equation to be balanced the products would be MOH and H2
gas and 2 moles of M would be needed.
9. Oxides of the active metals combine with water to form __________.
(a). metal hydroxides
(b). metal hydrides
(c). water and a salt
(d). oxygen gas
10. Oxides of the active metals combine with acids to form __________.
(a). hydrogen gas
(b). metal hydrides
(c). water and a salt
(d). oxygen gas
11. Oxides of most nonmetals combine with water to form __________.
(a). an acid
(b). a base
(c). water and a salt
(d). water
Explanation: Most nonmetal oxides will combine with water to produce an acidic
solution, while most metal oxides will combine with water to produce a basic
solution.
12. The element phosphorus exists in two forms in nature called white phosphorus and
red phosphorus. These two forms are examples of __________.
(a). isotopes
(b).allotropes
(c). azeotropes
(d). metrotropes
Explanation: Allotropes are different forms of the same element in the same state.
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Chapter 7
13. Of the hydrogen halides, only __________ is a weak acid.
(a). HC1 (aq)
(b). HBr (aq)
(c). HI (aq)
(d).HF (aq)
14. Of the halogens, which are gases at room temperature and atmospheric pressure?
(a). fluorine, bromine, and iodine
(b). fluorine, chlorine, and bromine
(c). fluorine, chlorine, bromine, and iodine
(d).fluorine and chlorine
Explanation: Of the 4 common halogens, bromine is a liquid at room temperature
and pressure while iodine is a solid.
15. The only noble gas that does not have the ns2np6 valence electron configuration is
__________.
(a). radon
(b). neon
(c). helium
(d). krypton
Explanation: Helium has only 2 electrons and thus does not have the ns2np6 electron
configuration like all other noble gases.
16. Atomic radius generally increases as we move __________.
(a). down a group and from right to left across a period
(b). up a group and from left to right across a period
(c). down a group and from left to right across a period
(d). there is no trend
Explanation: The outermost electrons are added to new shells down a group while
they are added to the same shell across a row. Thus atomic radius increase down a
group but reduces from the left to the right across a row.
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Chapter 7
17. Screening by the valence electrons in atoms is __________.
(a). less efficient than that by core electrons
(b). more efficient than that by core electrons
(c). essentially identical to that by core electrons
(d). both more efficient than that by core electrons and responsible for a general
increase in atomic radius going across a period.
Explanation: Screening by the core electrons (the electrons that are in the inner
shells) would be more efficient than that by the valence electrons since the valence
electrons are in the outermost shell and thus quite far away from the nucleus
compared to the core electrons.
18. The atomic radius of main-group elements generally increases down a group because
__________.
(a). effective nuclear charge increases down a group
(b). effective nuclear charge decreases down a group
(c). both effective nuclear charge increases down a group and the principal quantum
number of the valence orbitals increases
(d).the principal quantum number of the valence orbitals increases
19. Which of the following correctly lists the five atoms in order of increasing size
(smallest to largest)?
(a). O < F < S < Mg < Ba
(b).F < O < S < Mg < Ba
(c). F < O < S < Ba < Mg
(d). O < F < S < Ba < Mg
Explanation: Fluorine and oxygen are in the same period (#2) and next to each other
with F being the smallest of these 5 atoms. Ba is in group 2A and in row 6 (farthest
“down” a group) and is the largest of the atoms. Mg is in group 2A and in the third
period and hence will be bigger than F, O and S. Even though S is in the same period
as Mg it is in group 6A making it smaller than Mg.
20. Which of the following correctly lists the five atoms in order of increasing size
(smallest to largest)?
(a). F < K < Ge < Br < Rb
(b). F < Ge < Br < K < Rb
(c). F < K < Br < Ge < Rb
(d).F < Br < Ge < K < Rb
Explanation: Fluorine is in group 7A and period 2 making it the smallest of the 5
atoms here. Br is also in group 7A but is in period 4 making it larger than F, Ge is in
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group 4A and also in period 4 but is to the left of Br making it larger than Br. K and
Rb are both in group 1A but K is in period 4 and Rb is in period 5, making the Rb
atom the largest of all the 5 atoms.
21. Of the following atoms, which has the largest first ionization energy?
(a). Br
(b).O
(c). C
(d). P
Explanation: The ionization energy (IE) typically increases from left to right in a
period and decreases from top to bottom in a group. Thus for C and O which are in
the same period, O will have the larger IE. Br is in period #4 and will have the lowest
IE out of these 4 elements.
22. Of the following elements, which has the largest first ionization energy?
(a). Na
(b). A1
(c). Se
(d).C1
Explanation: The ionization energy (IE) typically increases from left to right in a
period and decreases from top to bottom in a group. Na, Al and Cl are all in period 3
with the chlorine atom to the farthest right and will have the highest IE.
23. __________ have the lowest first ionization energies of the groups listed.
(a). Alkali metals
(b). Transition elements
(c). Halogens
(d). Alkaline earth metals
Explanation: The ionization energy (IE) is the minimum energy needed to remove an
electron from the ground state of the isolated gaseous atom or ion. Of the groups
listed in this question the elements in the alkali metals group will be the ones that are
most willing to lose an electron (lowest first IE) since this will essentially lead to an
ion with the electron configuration of the previous noble gas.
24. Which of the following has the largest second ionization energy?
(a). Si
(b). Mg
(c). A1
(d).Na
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Explanation: The second ionization energy (IE) is the minimum energy needed to
remove two electrons from the ground state of the isolated gaseous atom or ion. If an
atom reaches a stable noble gas configuration after the removal of the first electron
then naturally the second IE will be higher as it will resist losing its noble gas electron
configuration. Of the 4 elements listed in this question, Na will have reached the
noble gas configuration after losing one electron and will have the highest second IE.
25. Which of the following has the largest second ionization energy?
(a). Ca
(b).K
(c). Ga
(d). Ge
Explanation: The second ionization energy (IE) is the minimum energy needed to
remove two electrons from the ground state of the isolated gaseous atom or ion. If an
atom reaches a stable noble gas configuration after the removal of the first electron
then naturally the second IE will be higher as it will resist losing its noble gas electron
configuration. Of the 4 elements listed in this question, K will have reached the noble
gas configuration after losing one electron and will have the highest second IE.
26. Which equation correctly represents the first ionization of aluminum?
(a). Al- (g)
(b). Al (g)
(c). Al (g) + e(d).Al (g)
Al (g) + eAl - (g) + eAl - (g)
Al + (g) + e-
27. Which ion below has the largest radius?
(a). C1(b). K+
(c). Br(d). FExplanation: Typically cations are smaller than their parent atoms while anions are
larger than the parent atoms. Of the atoms here, the Br atom would be the largest as
it is farthest down the group and hence its anion also will be the largest ion.
28. The ion with the smallest radius is __________.
(a). Br(b). C1(c). O2(d).F-
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Explanation: Typically anions are larger than the parent atoms. Of the atoms here,
the F atom would be the smallest as it is farthest down the group and hence its anion
also will be the smallest ion.
29. Which of the following is an isoelectronic series?
(a). B5-, Si4-, As3-, Te2(b).O2-, F-, Ne, Na+
(c). S, C1, Ar, K
(d). None of the above
Explanation: Isoelectronic series contain a combination of atoms and ions or only
ions with the same number of electrons. Here the series containing the O2-, F-, Ne
and Na+ is the only one where all atoms/ions contain 10 electrons.
30. __________ is isoelectronic with argon and __________ is isoelectronic with neon.
(a). C1-, F(b). C1-, C1+
(c). F+, F(d). Ne-, Kr+
Explanation: The Cl- ion has 18 electrons and is isoelectronic with argon while the Fion has 10 electrons making it isoelectronic with neon.
31. Chlorine is much more apt to exist as an anion than is sodium. This is because
__________.
(a). chlorine is bigger than sodium
(b). chlorine has a greater ionization energy than sodium does
(c). chlorine has a greater electron affinity than sodium does
(d). chlorine is a gas and sodium is a solid
32. Which of the following is not a characteristic of metals?
(a). acidic oxides
(b). low ionization energies
(c). malleability
(d). ductility
Explanation: Metals form basic oxides.
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33. When two elements combine to form a compound, the greater the difference in
metallic character between the two elements, the great the likelihood that the
compound will be __________.
(a). a gas at room temperature
(b).a solid at room temperature
(c). metallic
(d). nonmetallic
Explanation: A large difference in the metallic character of elements would mean
that the compound formed by the combination of these two elements will be ionic and
a solid at room temperature.
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