Chemistry 112

1. Chemistry 112 Ionic and Metallic Bonding

2. Valence Electrons • We now know that the ways in which elements behave is due to its electron configuration • Elements within groups behave similarly with one another because they have very similar e- configurations • The number of valence e- is identical from one element to the next within a group

3. How do we know how many valence e- there are in an atom? • The periodic table divides elements into groups • The group number corresponds to the number of valence e- in the outermost orbital of a particular atom • Ex. Group 14 elements = 4 valence e-

4. Electron Dot Structures • Valence e- are those typically involved in making bonds with other atoms • We can write valence e- in the form of electron dot structures • Valence e- are represented as dots around an electron’s symbol • Table 7.1, page 188

5. The Octet Rule • Atoms tend to achieve an electron configuration like that of noble gases • An octet is a group of eight • Atoms of metals tend to lose valence e-, leaving a complete octet at a lower level • Nonmetals tend to gain e- in order to have a filled octet where their valence e- currently are

6. Formation of Cations • An ion forms when an atom gains or loses e- • When an atom loses an e-, it becomes positively charged • It is otherwise referred to as a cation • Figure 7.2, p. 189

7. Exceptions to the Octet Rule • Many of the transition elements do not follow the octet rule • Configurations make take on a pseudo noble-gas configuration • Ex. Silver, copper, gold and cadmium

8. Formation of Anions • An anion is an ion with a negative charge • The suffix of an anion changes to –ide • It is easier for anions to gain e- in order to achieve a filled outermost orbital • Specifically, when halogens gain an e- to achieve a stable octet, it becomes a halide ion