Chapter 15 Ionic Bonding & Ionic Compounds.
1 Electron Configuration in Ionic Bonding.
Find the valence of an electron just look at the group number. For example Carbon and Silicon, in Group 4A, have 4 valence electrons. The noble gases are the only exceptions to the group rule: Helium has 2 valence electrons, and all the other noble gases have 8.
Gilbert Lewis found the octet rule (look at vocabulary).
Atoms in compounds are held together by chemical bonds. Chemical bonds result from the shaping or transfer of valence electrons between pairs of atoms.
Bonded atoms attain the stable electron configuration of a noble gas. The noble gases themselves exist as isolated atoms because that it their most stable condition.
For the representative elements, the # of valence electrons is = to the element's group # in the periodic table.
The transfer of one or more valence electrons between atoms produced positively and negatively charged ions, or cations and anions, respectively. Most common cations are produced by the loss of valence electrons from metal atoms.
15.2 Ionic Bonds.
The attraction between an anion and a cation is an ionic bond. A substance with ionic bonds is an ionic compound.
Nearly all ionic compounds are crystalline solids at room temperature. They generally have high melting points. The total positive charge in an ionic compound is balanced by the total negative charge; thus ionic compounds are electrically neutral.
Ionic solids consist of positive & negative ions packed in an orderly arrangement. The coordination number of an ion indicates the number of ions of opposite charge that surrounds the ion in a crystal.
When melted or in aqueous solution, ionic compounds can conduct electricity because the ions can move freely when a voltage is applied.
15.3 Bonding in Metals.
Metals are like ionic compounds in some ways. They consist of positive metal ions packed together and surrounded by a sea of valence electrons.
