CK-12-Chemistry Intermediate

http://www.ck12.org Chapter 8. Ionic and Metallic Bonding

FIGURE 8.3

(A) Iron(III) oxide, Fe 2 O 3 , is the primary

component of rust. (B) Iron(II) sulfate,

FeSO 4 , has been known since ancient

times as green vitriol and was used for

centuries in the manufacture of inks.

Others may attain configurations that include a fulldsublevel, such as zinc and copper.

Zn → Zn^2 ++ 2 e−

[Ar]3d^104 s^2 [Ar]3d^10

Cu → Cu++e−

[Ar]3d^104 s^1 [Ar]3d^10

The resulting configuration above, with 18 electrons in the outermost principal energy level, is referred to as a pseudo
noble gas electron configuration. It gives particular stability to the Zn^2 +and Cu+ions.

Lesson Summary

• An electron dot diagram shows the chemical symbol of an element with dots that represent valence electrons
  evenly distributed around the symbol.


• The octet rule states that elements form chemical compounds so that each atom will acquire the electron
  configuration of a noble gas. Most noble gases have eight valence electrons, except for helium, which has
  only two.


• Representative metals generally lose all of their valence electrons when forming ions, leaving them with a
  complete octet of electrons from the next-lowest energy level. Most nonmetals gain electrons when forming
  ions until their outer energy level has acquired an octet.


• Atoms and ions that have the same electron configuration are called isoelectronic. Common ions of represen-
  tative elements are isoelectronic with a noble gas.


• When forming ions, transition metals lose their valences-sublevel electrons before they lose theird-sublevel
  electrons. Half-filled or completely filleddsublevels give transition metal ions greater stability.

Lesson Review Questions

Reviewing Concepts

1. What is the maximum number of valence electrons that an atom can have?