Metals and Nonmetals and Their Ions
At some point in life, you stumble across the words metals and nonmetals, whether in the middle of a conversation about rusty bike fenders or as vocabulary terms in a science textbook in fifth grade, and think to yourself, “metal, like copper, conducts electricity, and nonmetal, like wood, doesn’t.” You might have some general conceptions about metals and nonmetals from personal experience, but there are several more characteristics that contribute to their own uniqueness. On the periodic table, the elements can be divided into two broad categories: metals and nonmetals. There are also subgroups in each category that further accounts for all the properties of the elements.
Properties of Metals and Nonmetals
Metal characteristics include luster, heat and electricity conductivity, malleability (ability to bend instead of crumble), ductility (ability to be shaped or molded), and high melting point. Also, metals are usually reducing agents with lower electronegativities. Metal oxides form a base when they react with water:
Ex: K2O(s) + H2O(l) ----> 2K+(aq) + 2OH-(aq)
(metal oxide) (base)
Nonmetals display dullness, poor heat and electricity conductivity, brittleness (crumble instead of bend), and exist mostly in the liquid or gas form due to lower density and melting points. They are also good oxidizing agents and usually have higher electronegativities. Nonmetal oxides form an acid when they react with water:
Ex: SO3(g) + H2O(l) ----> H2SO4 (aq)
(nonmetal oxide) (acid)
The Periodic Table
Ions of Metals and Nonmetals
Ions: An atom or group of atoms gain an electric charge by gaining or losing an electron, usually through bonding. Cation: An atom loses electrons and is positive ex: Ca2+. Anion: An atom gains electrons and is negative ex: Cl-.
Metals usually form cations while Nonmetals usually form anions.
All elements on the periodic table (with the exception of noble gases) strive for one of the following more-stable electron configurations:
Ions of Periodic Groups
Properites of Metals and Nonmetals when they bond
1. Ionic bonds takes place when there's a nonmetal and a metal that exchange electrons.
For Example: Na+ + Cl- = NaCl
Metal + Nonmetal = Ionic
2. Covalent bonds are when electrons are shared between two nonmetals.
For Example: H2 + 2F- = 2HF
Nonmetal + Nonmetal = Covalent
In a bond, the charge each element/molecule in a chemical reaction carries over to the element/molecule it is bonding to.
` For Example: Ca2+ + 2NO3- = Ca(NO3)2
The charge of 2+ from the calcium carries over to the NO3 and the charge of 1- from nitrate carries over to the Ca.
Apply knowledge about ions to write the following compounds
1) Ca & Cl
Answer: CaCl2 (Ca2+ + 2Cl-)
2) Fe & S
Answer: Fe(II)S (Fe2+ + S2-)
Apply knowledge about Ions to write oxidation state of the following
Answer: O - O.S. of -2 C - O.S. of +3
(4x -2 charge of O4 is -8, but this polyatomic ion has an overall charge of -2, which means C2 has a charge of +6, which gives C a charge of +3) ---> (2 x +3)+(4 x -2) = 6 - 8 = -2, which is overall charge of the ion
Answer: O - O.S. of -2 H - O.S. of +1 C - O.S. of 4+
(3x -2 charge of O3 is -6; H has charge of +1 so it becomes -5, but this anion has an overall charge of -1, which gives C a charge of 4+) ---> (1 x +1)+(1 x +4)+(3 x -2) = 1 + 4 - 6 = -1, which is overall charge of the ion
Apply knowledge about oxides to determine whether the product will be an acid or a base
1) MgO + H2O ---->
Answer: product will be a base because MgO is a metal oxide
MgO + H2O ----> Mg2+ + 2OH-
2) SO2 + H2O ---->
Answer: product will be an acid because SO2 is a nonmetal oxide
SO2 + H2O ----> H2SO3