PROBLEM \(\PageIndex{1}\) Does a cation gain protons to form a positive charge or does it lose electrons? Answer The protons in the nucleus do not change during normal chemical reactions. Only the outer electrons move. Positive charges form when electrons are lost. PROBLEM \(\PageIndex{2}\) Iron(III) sulfate [Fe 2 (SO 4 ) 3 ] is composed of Fe 3+ and \(\ce{SO4^2-}\) ions. Explain why a sample of iron(III) sulfate is uncharged. Answer Two cations with a +3 charge give a total of +6 charge, while three anions of -2 charge give a total of -6 charge. +6-6=0, so when these ions bond, the charges will cancel, leaving the resulting compound uncharged. PROBLEM \(\PageIndex{3}\) Which of the following atoms would be expected to form negative ions in binary ionic compounds and which would be expected to form positive ions: P, I, Mg, Cl, In, Cs, O, Pb, Co? Answer P, I, Cl, and O would form anions because they are nonmetals. Mg, In, Cs, Pb, and Co would form cations because they are metals. PROBLEM \(\PageIndex{4}\) Which of the following atoms would be expected to form negative ions in binary ionic compounds and which would be expected to form positive ions: Br, Ca, Na, N, F, Al, Sn, S, Cd? Answer Anions: Br, N, F, S, Cations: Ca, Na, Al, Sn (because it's a metal), Cd (because it is a metal) PROBLEM \(\PageIndex{5}\) Predict the charge on the monatomic ions formed from the following atoms in binary ionic compounds: P Mg Al O Cl Cs Answer a P 3– Answer b Mg 2+ Answer c Al 3+ Answer d O 2– Answer e Cl – Answer f Cs + PROBLEM \(\PageIndex{6}\) Predict the charge on the monatomic ions formed from the following atoms in binary ionic compounds: a. I b. Sr c. K d. N e. S f. In Answer a I - Answer b Sr 2+ Answer c K + Answer d N 3- Answer e S 2- Answer f In 3+ PROBLEM \(\PageIndex{7}\) Write the noble gas electron configuration for each of the following ions: a. As 3– b. I – c. Be 2+ d. Cd 2+ e. O 2– f. Ga 3+ g. Li + h. N 3– i. Sn 2+ j. Co 2+ k. Fe 2+ l. As 3+ Answer a [Ar]4 s 2 3 d 10 4 p 6 Answer b [Kr]4 d 10 5 s 2 5 p 6 Answer c 1 s 2 Answer d [Kr]4 d 10 Answer e [He]2 s 2 2 p 6 Answer f [Ar]3 d 10 Answer g 1 s 2 Answer h [He]2 s 2 2 p 6 Answer i [Kr]4 d 10 5 s 2 Answer j [Ar]3 d 7 Answer k [Ar]3 d 6 Answer l [Ar]3 d 10 4 s 2 PROBLEM \(\PageIndex{8}\) Write out the full electron configuration for each of the following atoms and for the monatomic ion found in binary ionic compounds containing the element: Al Br Sr Li As S Answer a Al: 1 s 2 2 s 2 2 p 6 3 s 2 3 p 1 Al 3+ : 1 s 2 2 s 2 2 p 6 Answer b Br: 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 3 d 10 4 s 2 4 p 5 Br - : 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 3 d 10 4 s 2 4 p 6 Answer c Sr: 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 3 d 10 4 s 2 4 p 6 5 s 2 Sr 2+ : 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 3 d 10 4 s 2 4 p 6 Answer d Li: 1 s 2 2 s 1 Li + : 1 s 2 Answer e As: 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 3 d 10 4 s 2 4 p 3 As 3 - : 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 3 d 10 4 s 2 4 p 6 Answer f S: 1 s 2 2 s 2 2 p 6 3 s 2 3 p 4 S 2- : 1 s 2 2 s 2 2 p 6 3 s 2 3 p 6 PROBLEM \(\PageIndex{9}\) What information can you use to predict whether a bond between two atoms is covalent or ionic? Answer The position of the two atoms on the periodic table: two nonmetals form a covalent bond, while a metal and a nonmetal form an ionic bond. Have a video solution request? Let your professors know here. ***Please know that you are helping future students - videos will be made in time for next term's class. Feedback Think one of the answers above is wrong? Let us know here .