Lesson 4 Ionic and Molecular Compounds

As you may have already guessed, there are not spare electrons floating around for non-metal atoms to grab. The electrons that non-metal atoms need to gain come from metal atoms that need to lose electrons to achieve a full valence. There is a transfer of electrons from a metallic atom to a non-metallic atom, thus creating an ion. Next, there will be an electrostatic attraction between cations (+) and anions (–). This attraction is an ionic bond and results in the formation of ionic compounds.

This video illustrates the formation of ionic bonds. There are a few differences to keep in mind.

1. In the modified Bohr diagrams they use, they place the electrons separate in the first energy level.
2. At times, they place two electrons in one orbital.

Please note

• the transfer of electrons
• the attraction between cations and anions
• The large number of ions involved to create a crystal lattice

Ionic formulas do not represent the actual number of each element in the large crystal structure, or else the formula for sodium chloride might be «math xmlns=¨http://www.w3.org/1998/Math/MathML¨»«msub»«mi»Na«/mi»«mo»§#8734;«/mo»«/msub»«msub»«mi»Cl«/mi»«mo»§#8734;«/mo»«/msub»«/math»! Ionic formulas are always written as the lowest ratio of cations to anions. In this case, it is a 1:1 ratio; so the formula is NaCl.

Crystal lattices can come in a variety of shapes and ratios of cations to anions.

Giant Ionic Structures/Lattices @ YouTube FuseSchool – Global Education 

This video illustrates the formation of crystal lattice structures and the properties that result from these structures.