CHM120H5 Midterm: Term Test II -- Concepts, Theories, Rules, Principles, ETC

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3 Mar 2017

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Ionization energy is the minimum amount of energy required to remove the most loosely bound electron to a neutral isolated gaseous atom in the ground state. If more energy is required the electron will move at a faster speed. ** paired electrons are removed more easily because they repel each other which reduced the attraction of the nucleus. **period 2 ionization energies are lower than period 3. This is because of the decrease in the size of the atoms. As the size decreases, the electrons are well held by the nucleus energy. As the table progresses from left to right, more electrons are added, however there are also more protons added, this causes an increase in the nucleus energy, which results in an increase in ionization energy. As the first electron is removed from a neutral isolated gaseous atom at ground state, the electron:proton ratio increases.

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True or False.

(a) Effective nuclear charge (Zeff) is the positive charge experienced by the electron from the nucleus and it increases from left to right across the period. Answer: __________

(b) Effective nuclear charge slightly decreases going down a group. Answer: __________

(d) Atomic radius tends to decrease from top to bottom of a group because of the increase in the principle quantum number. Answer: __________

(e) Anions are larger than their parent atoms because electrons are added to the valence shell reducing the electron-electron repulsions. Answer: __________

(f) Al3+ is larger than Na+ because Na+ has two extra electrons. Answer: __________

(g) The ionization energy of Na2+ is significantly higher than Na+ because it takes more energy to remove the inner-shell electron. Answer: __________

(h) Bromine, calcium and sodium are metallic elements because they are on the left side of the periodic table. Answer: __________

(i) Calcium, antimony, and silicon are metalloids that their properties fall between those of metals and those of nonmetals. Answer: __________

(j) Lattice energy is the energy required to completely separate one mole of solid ionic compound into its gaseous ions and it is always a negative number. Answer: __________

1)The NaCl2 ionic salt does not exist. Which of the followingstatements best explains why?

A. Because the formation of Na2+ is an unfavorable process due tothe great amount of energy required to remove the 2nd electron fromthe Na atom (the 2nd electron would have to be removed from thecore electrons of the Na atom).
B. Because the Cl- anion is too large for there to be two of themattached to one Na+ ion.
C. Because NaCl2 is actually a polyatomic ion with a -1 charge, andnot an ionic salt. In the presence of another Na+ ion, the Na2Cl2salt would form.
D. Because Cl2 has no charge and therefore would not be attractedelectrostatically to the positively charged Na2+ cation.

2)Select the false statement below.

A. The first ionization energy of an atom is smaller than thesecond ionization energy of the same atom.
B. Phosphorus has a greater first ionization energy than magnesium,and the reason for this is because P has a greater effectivenuclear charge (Zeff) than Mg.
C. The following process is an endothermic process and representsthe first ionization energy of an atom A:A(g) ? A1+(g) + e1-
D. Fluorine has a greater first ionization energy than iodine, andthe reason for this is because fluorine has a greater amount ofshielding of outer electrons by inner electrons than doesiodine.

3)The Group 5A elements N,P,As have lower (less negative) electronaffinities than most of the Group 4A or Group 6A elements becauseN,P,As have half-filled subshells.

True
False

4)A fluorine atom is smaller than a bromine atom, and a potassiumatom is larger than a lithium atom.

True
False

5)A certain main-group element exhibits the following successiveionization energies in kJ/mol:

IE1 = 100; IE2 = 1200; IE3 = 2300; IE4 = 3100; IE5 = 4200

Select the false statement about this element below.

A. This is likely a Group 1A element.
B. This element is typically found uncombined in nature (that is,it is not usually found in compounds, but rather as a freeelement).
C. If this element is given a symbol of "J", it would form an ioniccompound with sulfur as J2S.
D. If this element was in period 2 of the periodic table, it wouldbe lithium.

6)Select the false statement below.

A. Generally speaking, non-metallic elements have greater effectivenuclear charge (Zeff) than metallic elements in the sameperiod.
B. Generally speaking, as you go down a group in the periodictable, there is successively greater shielding of the outer-shellelectrons by the inner-shell electrons.
C. Generally speaking, the heavier alkali metals can be predictedto exhibit greater shielding of the outer-shell electrons by theinner-shell electrons than lighter alkali metals.
D. Generally speaking, as you go across a period in the periodictable, the effective nuclear charge (Zeff) decreases because eachsuccessive element contains more protons in the nucleus than theprevious element and the outer electrons are all in the same shellas you go across a period.

7)Place the following in order of increasing size:

O2-, F1-, Li1+

A. F1- < Li1+ < O2-
B. Li1+ < O2- < F1-
C. Li1+ < F1- < O2-
D. F1- < O2- < Li1+

8)Select the false statement below.

A. The following set of quantum numbers is allowed:
n = 4, l = 2, ml = -2, ms = +1/2
B. The n = 1 shell of any given atom can accomodate up to 2electrons.
C. The n = 4 shell of any given atom can accomodate up to 16electrons.
D. In any given atom, the l = 2 subshell can accomodate up to 5electrons that have negative spins (ms =

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CHM120H5 Midterm: Term Test II -- Concepts, Theories, Rules, Principles, ETC

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