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Homework 1 key - Chemistry 3301 - Descriptive Inorganic...

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Unformatted text preview: Chemistry 3301 - Descriptive Inorganic Chemistry Spring Semester 2009 Homework 1 Key (1) Leaving out the Noble Gases, rank from highest to lowest the ten elements that have the greatest values for their first ionization energies. Write down anything that surprises you about this list. All values in kJ/mol F (1681.0) > N (1402.3) > O (1314.0) > H (1312.0) > Cl (1251.1) > Br (1139.9) > C (1086.4) > P (1011.8) > I (1008.4) > Hg (1007.0) Rank from highest to lowest the ten elements that have the greatest values for their first electron affinities. Write down anything that surprises you about this list. All values in kJ/mol Cl (349.0) > F (328.0) > Br (324.6) > I (295.18) > At (270.1) > Au (222.76) > Pt (205.3) > S (200.42) > Se (194.98) > Te (190.16) Rank from highest to lowest the ten elements that have the greatest values for their Pauling electronegativities. Write down anything that surprises you about this list. F (4.0) > O (3.5) > N (3.0) = Cl (3.0) > Br (2.8) > C (2.5) = S (2.5) = I (2.5) > Se(2.4) = Au (2.4) (4) From Silberberg’s chart of atomic radii (Resource #5 “Atomic Radii” that was sent to you via email), find three elements that do not obey the expected increasing or decreasing trend for a row or a column of the Periodic Chart. Indicate whether the element disobeys the trend for a row or for a column. Row: Column: (5) Ag, Au, Bi, Cd, Cu, Ga, Hg, In, Ir, Pd, Po, Pt, Te, Tl, Zn Ga, Hf (2) (3) For the following binary compounds, write the formal oxidation states of both elements, the electronegativity difference between them, and whether you would classify them as primarily ionic or primarily covalent. 4+ 1(a) TiBr4 Ti , Br , 1.3, covalent (b) FeS Fe , S , 0.7, covalent 2+ 2- Chemistry 3301 - Descriptive Inorganic Chemistry Spring Semester 2009 Homework 1 Key Ungraded Homework The following questions will not be graded for this homework, but questions very much like them will be on the exams. (4) Without looking at a table of values, rewrite the following elements from left to right according to the magnitudes of their atomic radii, starting with the smallest and ending with the largest. H(0.37) < Cl (100) < P (110) < As (120) < Co (125) < Ir (136) (5) Without looking at a table of values, rewrite the following elements from left to right according to the magnitudes of their Pauling electronegativities, starting with the lowest and ending with the highest value. Gd (1.2) < Co (1.8) < H (2.1) < Ir (2.2) < C (2.5) Questions to Think About (ungraded) Silberberg’s chart of atomic radii (Resource #5 “Atomic Radii”) lists values of atomic radii for the Noble Gases. According to the heading of the chart, the values are calculated from metallic radii (half of the interatomic distances in metal crystals) or from covalent radii (half of the distance of a single bond between two atoms of the same element (a “homonuclear” bond) in a covalent molecule). The Noble Gases are not metals, helium has never been solidified, and none of the Noble gases form covalent bonds to themselves. The question, therefore, is “What are these numbers and where do they come from?” The covalent radii of He, Ne, and Ar are estimates – they are not measured numbers. Radii for the other Noble Gases do not come from homonuclear bonds, since there are none, but might be estimated from other bonds. Naturally occurring oxygen is a mixture of O (99.762%), O (0.038%), and (0.200%). Why is the atomic mass of oxygen less than 16 (i.e. 15.9994)? Go to Wikipedia and search for “mass defect”. 16 17 18 O ...
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