# 19.1 Occurrence, preparation, and properties of transition metals  (Page 11/27)

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## Key concepts and summary

The transition metals are elements with partially filled d orbitals, located in the d -block of the periodic table. The reactivity of the transition elements varies widely from very active metals such as scandium and iron to almost inert elements, such as the platinum metals. The type of chemistry used in the isolation of the elements from their ores depends upon the concentration of the element in its ore and the difficulty of reducing ions of the elements to the metals. Metals that are more active are more difficult to reduce.

Transition metals exhibit chemical behavior typical of metals. For example, they oxidize in air upon heating and react with elemental halogens to form halides. Those elements that lie above hydrogen in the activity series react with acids, producing salts and hydrogen gas. Oxides, hydroxides, and carbonates of transition metal compounds in low oxidation states are basic. Halides and other salts are generally stable in water, although oxygen must be excluded in some cases. Most transition metals form a variety of stable oxidation states, allowing them to demonstrate a wide range of chemical reactivity.

## Chemistry end of chapter exercises

Write the electron configurations for each of the following elements:

(a) Sc

(b) Ti

(c) Cr

(d) Fe

(e) Ru

(a) Sc: [Ar]4 s 2 3 d 1 ; (b) Ti: [Ar]4 s 2 3 d 2 ; (c) Cr: [Ar]4 s 1 3 d 5 ; (d) Fe: [Ar]4 s 2 3 d 6 ; (e) Ru: [Kr]5 s 2 4 d 6

Write the electron configurations for each of the following elements and its ions:

(a) Ti

(b) Ti 2+

(c) Ti 3+

(d) Ti 4+

Write the electron configurations for each of the following elements and its 3+ ions:

(a) La

(b) Sm

(c) Lu

(a) La: [Xe]6 s 2 5 d 1 , La 3+ : [Xe]; (b) Sm: [Xe]6 s 2 4 f 6 , Sm 3+ : [Xe]4 f 5 ; (c) Lu: [Xe]6 s 2 4 f 14 5 d 1 , Lu 3+ : [Xe]4 f 14

Why are the lanthanoid elements not found in nature in their elemental forms?

Which of the following elements is most likely to be used to prepare La by the reduction of La 2 O 3 : Al, C, or Fe? Why?

Al is used because it is the strongest reducing agent and the only option listed that can provide sufficient driving force to convert La(III) into La.

Which of the following is the strongest oxidizing agent: ${\text{VO}}_{4}{}^{3},$ ${\text{CrO}}_{4}{}^{2-},$ or ${\text{MnO}}_{4}{}^{\text{−}}\text{?}$

Which of the following elements is most likely to form an oxide with the formula MO 3 : Zr, Nb, or Mo?

Mo

The following reactions all occur in a blast furnace. Which of these are redox reactions?

(a) ${\text{3Fe}}_{2}{\text{O}}_{3}\left(s\right)+\text{CO}\left(g\right)\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{2Fe}}_{3}{\text{O}}_{4}\left(s\right)+{\text{CO}}_{2}\left(g\right)$

(b) ${\text{Fe}}_{3}{\text{O}}_{4}\left(s\right)+\text{CO}\left(g\right)\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}\text{3FeO}\left(s\right)+{\text{CO}}_{2}\left(g\right)$

(c) $\text{FeO}\left(s\right)+\text{CO}\left(g\right)\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}\text{Fe}\left(l\right)+{\text{CO}}_{2}\left(g\right)$

(d) $\text{C}\left(s\right)+{\text{O}}_{2}\left(g\right)\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{CO}}_{2}\left(g\right)$

(e) $\text{C}\left(s\right)+{\text{CO}}_{2}\left(g\right)\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}\text{2CO}\left(g\right)$

(f) ${\text{CaCO}}_{3}\left(s\right)\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}\text{CaO}\left(s\right)+{\text{CO}}_{2}\left(g\right)$

(g) $\text{CaO}\left(s\right)+{\text{SiO}}_{2}\left(s\right)\phantom{\rule{0.2em}{0ex}}⟶\phantom{\rule{0.2em}{0ex}}{\text{CaSiO}}_{3}\left(l\right)$

Why is the formation of slag useful during the smelting of iron?

The CaSiO 3 slag is less dense than the molten iron, so it can easily be separated. Also, the floating slag layer creates a barrier that prevents the molten iron from exposure to O 2 , which would oxidize the Fe back to Fe 2 O 3 .

Would you expect an aqueous manganese(VII) oxide solution to have a pH greater or less than 7.0? Justify your answer.

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