Ions

Quick Review of Electron Configuration Electrons are found in the electron cloud, but they’re not just placed anywhere. Electrons are found on different energy levels around the nucleus, and each energy level has a maximum number of electrons that it can hold 1st level = 2 2nd level = 8 3rd level = 18 4th level = 32 Keep in mind, these are the maximum they can hold and not always the most stable configuration.

5 6 Take the element Boron! How many Protons? How many Neutrons? How many Electrons? Where will they go? 5 6

10 10 Take the element Neon! How many Protons? How many Neutrons? How many Electrons? Where will they go? 10 10

Take the element Neon! What are the electrons in the outermost shell called? What is the “ideal” amount to have? 10 10

Ions Atoms are identified by which particle? Different Isotopes have different? So, which particle do you think identifies Ions???

Ions Ions form when an atom gains or loses electrons. Why do they do that? Atoms gain or lose electrons in order to reach a stable configuration.

+ + + Ions - - - If the atom is neutral, how many electrons? Let’s look at a normal atom of Lithium. Protons? + + + If the atom is neutral, how many electrons? - - -

+ + + +1 Is the atom still neutral? Can we ever change the number of protons and still have a Lithium Atom? + + + What if the atom lost an electron to become stable. - - Is the atom still neutral? What would be the charge of this atom now? +1 This is called an oxidation number.

Li+1

+ + + -1 - - - - Is the atom still neutral? What if the atom gained an extra electron to become stable. - - - - Is the atom still neutral? What would be the charge of this atom now? -1 This is called an oxidation number.

Trends in Oxidation Numbers

Atoms of elements and Ions of elements are different Sodium is a soft, silvery highly reactive metal. It is used in making light bulbs and for heat exchange in nuclear reactors. A pale yellow-green gas, chlorine killed soldiers in WWI. Today it mainly purifies drinking water and swimming pools.

Ions of elements Combined together sodium and chlorine make common table salt and are thus essential to life. Table salt consists of sodium ions (Na+) and chloride ions (Cl-)

In review…. If an atom loses electrons, the overall charge of the atom becomes positive. Positive because there will be more protons than electrons. If an atom gains extra electrons, the overall charge of the atom becomes negative. Negative because there will be more electrons than protons.

So what if you see this? An ion of Nitrogen has a -3 charge. What happened? How many total electrons does this ion have? An ion of Magnesium has a +2 charge.

Ion Vocabulary Review An ion is an atom or group of atoms that have a charge. The charge on the atom is called an oxidation number. A monatomic ion is an atom with a charge. A polyatomic ion is a group of atoms with a charge. A cation is a positive ion. An anion is a negative ion.