english chemistry exercises, Exercises of Chemistry

Download english chemistry exercises and more Exercises Chemistry in PDF only on Docsity! 1) 9-1 PRACTICE EXAMPLE A: Use the periodic table on the inside front cover to predict which is the smallest atom: As, I, or S. S is located in the third period and so that it has less electronic shells than As (fourth period) and I (fifth period). Furthermore, the outermost electron shell of S is 3s23p4 without orbital d, f while the electron configuration of As is 3d10 4s2 4p3 and I is 4d10 5s2 5p5. Electrons in filled inner shells (d) are highly effective at shielding electrons in outer shells (ns np) from the nuclear charge, whereas electrons in the same principal shell are not very effective at shielding one another from the nuclear charge. So it reduces the attraction of the nucleus to the outer electrons.  S has the smallest atomic radius. It is the smallest atom. 3) 9-2 PRACTICE EXAMPLE A: Refer only to the periodic table on the inside front cover, and arrange the following species in order of increasing size: Ti2+, V3+, Ca2+, Br-, and Sr2+. Ca2+ and Sr2+ have the same charge. They are both the ions of group 2A’s elements. The ionic radius increases going down a column. => Ca2+< Sr2+ Ca2+ and Ti2+ have the same charge and the same fourth period. The ion radius decreases going from left to right in a period. => Ti2 + < Ca2+ Ti2+ and V3+ are isoelectronic, as the positive charge of the nucleus increases while the number of electrons remains the same, there is a greater electrostatic attraction between the electrons and the nucleus, which causes a decrease in radius. => V3 < Ti2+ Similarly, Br- and Sr2+ are isoelectronic. The nuclear charge of Br- is smaller than Sr2+’s => Sr2+ < Br-  V3 < Ti2+ < Ca2+ < Sr2+ < Br- 17) Among the following ions, several pairs are isoelec-tronic. Identify these pairs. Fe2+, Sc3+, Ca2+, F-, Co2+, Co3+, Sr2+, Cu+, Zn2+, Al3+. - Sc3+ and Ca2+ both have the same electron configuration: [Ne] 3s2 3p6 - Fe2+ and Co3+ both have the same electron configuration: [Ar] 3d5 4s1 - F- and Al3+ both have the same electron configuration: 1s2 2s2 2p6 - Cu+ and Zn2+ both have the same electron configuration: [Ar] 3d8 4s2 31) Compare the elements Al, Si, S, and Cl. b) Place the elements in order of increasing electron affinity. Based on the table of figures 9-15 on page 397, the electron affinity of Al: - 42,5 Si: -133,6 S: -200,4 Cl: -349,0  Al < Si < S < Cl 21) Use principles established in this chapter to arrange the following atoms in order of increasing value of the first ionization energy: Sr, Cs, S, F, As. In the periodic table, we know that first ionization energies increase diagonally from the lower left of the periodic table to the upper right, so we can predict that the element at the bottom left will have the lowest first ionization energy: Cs. Next, sorting in the order diagonally from the bottom to the top are the elements: Sr, As, S. Finally, F is located in the top right corner of table (not mentioned the noble gases), so it has the greatest ionization energy of all the elements.  Cs < Sr < As < S < F. 55) Two elements, A and B, have the electron configuration: A: [Ar] 4s1 B: [Ar] 3d104s24p3 . a) Element is metal: A (alkali metal because it has only one valence electron)