Chapter 5: Ions & Ionic Compounds Jessica Alphonse

Chemical Reactivity Some elements are very reactive and some are not. The way you can tell how reactive an element can be, all depends on electronic configuration. Ex. O2= 1s2,2s2, 2p4. The 2p orbital in o2 have four electrons. The noble gases are the least reactive because they already have 8 electrons and follow the octet rule. “Alkali metals & Halogens are the most reactive because they have only one electron.” (Ch.5, p.158) (Citation-Ch.5, p 158)

Valence Electrons & Stable Ions The small number on the electron configurations represent how many electrons an atom has. To find out how many electrons an atom has, simply look at the periodic table. In order to form stable ions, atoms must gain or lose electrons to form stable ions. Ion- “an atom that’s gained or lose one electron that has a negative or positive charge.”(Ch.5, p.161) Cation- “an ion with a positive charge.” (Ch.5, p.161) Anion- “an ion with a negative charge.”(Ch.5, p.161)

Ionic Bonding and Compounds During an ionic bond, cations and anions should attract each other. It takes a good amount of energy for electrons to be transferred from an atom from a negative to a positive charge. Ionic compounds are very strong and have distinctive properties. The compounds have ions that can’t be in fixed locations. They also are never gaseous when they reach a boiling temperature.

How to Name & Write Ionic Compounds/Formulas To name an ionic compound, simply name the cation and the anion by borrowing any of the element name. Ex. K+ = Potassium ion. They’re also called binary ionic compounds because it contains two elements. To write an ionic formula, it has to be balance. Therefore the positive and the negative charge must be the same. Ex. Na+ & Cl- have 1 electron.

Polyatomic Ions Polyatomic ions are a group of bonded atoms charged. Polyatomic ions are also made out of several elements that are either positive or negative. To name a polyatomic ion, most of them have oxygen; so the ending either has –ite or –ate. Ex. Sulfide (SO2/3)= sulfate or sulfite. When an ion has hydrogen, the prefixes have mono- or di-. Ex. CO2 = carbon dioxide.

Citations Meyers, R. Thomas, et al. Holt Chemistry . Austin, TX: Rienhart & Winston, 2004 Slide 2: Ch.5, p.158 Slide 3: Ch.5, p.160-163 Slide 4: Ch.5, p.166 & p.171 Slide 5: Ch.5, p.176-178 Slide 6: Ch.5, p.178