CHEM 101 1st Edition Lecture 5 Outline of Last Lecture I. Continuation of Periodic Table of Elements Groups II. Molecules, Ions and their CompoundsOutline of Current Lecture I. Molecules, Ions and their Compounds (continued)II. Names of AnionsIII. Names of Polyatomic IonsIV. Names of Ionic Compounds (Salts)V. Ionic CompoundsCurrent Lecture- Clicker question: The molecule depicted here is one of the essential amino acids (Alanine). What is the molecular formula of the acid? H H O H-N-C-C-O-H H-C-H C o A.C3H5NOo B.C3H5NO2o C.C3H6NO2o D. C3H7NO2 (correct answer)- Molecules, Ions and their Compounds (continued)o Ionic compounds (usually a combination of metals and non-metals) constitute another major class of compounds. Many familiar compounds are composed of ions. Table salt, or sodium chloride (NaCl) is one example Ionic compounds are also called salts. They consist of ions- atoms or groups of atoms that bear a positive or negative electric charge- Removing electrons from an atom produces a cation with a positive charge. Forms when an atom loses one or more electronso Metals usually lose electrons forming cationsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Adding electrons to an atom gives an anion with a negative charge. Forms when an atom gains one or more electronso Nonmetals usually gain electrons forming anions- By losing or gaining electrons, an atom has the same number of electrons as the nearest Noble gas atomo Transition Metal Cations These elements may have more than one charge state (called oxidation state). The charge number (oxidation number) can be concluded from the formula All metal cations are named after there representative element followed by the word “ion” or more specific “cation”:Sodium Na Na+ Sodium Ion Barium Ba Ba+ Barium IonAluminum Al Al+ Aluminum Ion Since the transition elements have multiple charge states, each of them must be identified uniquely:Cu Cu+ copper(I) ion or cuperous ionCu Cu2+ copper(II) ion or cupric ion- Names of Anionso NONMETAL + n e^(-) X^(n-)Where n = 8 – Group NumberGroup 4A Group 5A Group 6A Group 7AC^(4-), carbide N^(3-), nitride O^(2-), oxide F-, fluorideS^(2-), sulfide Cl-, chlorideBr-, bromideI-, iodideo Name derived by adding “ide” suffix- Names of Polyatomic Ionso Polyatomic ions are groups of atom (molecules) with a net chargeo We distinguish between polyatomic cations and polyatomic anions Ex: Ammonium cation, NH4+o Polyatomic anions containing oxygen (oxoanions) are named by adding the suffix –ite or –ate to the name of the (nonmetal) element:NO2- nitriteNO3- nitrateSO3^(2)- sulfiteSO4^(2)- sulfateo Both monoatomic and some polyatomic anions are named by adding the suffix –ide to the name of the (nonmetal) element:CL- chlorideX- halogenideO^(2)- oxideOH- hydroxideCN- cyanideo A common example are the chlorine oxoanions:Cl- chlorideClO- hypochloriteClO2- chloriteClO3- chlorateClO4- perchlorate- Names of Ionic Compounds (Salts)Formula Ions Involved Name sCaCl2 Ca^(2+) and 2 Cl- calcium chloride(NH4)2CO3 2NH4+ and CO3^(2-) ammonium carbonateMg(OH)2 Mg^(2+) and 2 OH- magnesium hydroxide- Ionic Compoundso Cations and anions are attracted to each other by electrostatic forceso As ion charge increases, force of attraction increaseso As distance increases, force of attraction decreases Coulomb’s LawForce of attraction = -k *(n+ * e)(n- * e) d^2 where k proportional constantn+ = charge number of cationn- = charge number of anione= elemental charged= distance between ionso NaCl, Na+ and Cl- : melting point= 804 °Co MgO, Mg^(2+) and O^2-): melting point 2800 °C MgO with the greater charge and smaller distance between the nuclei of two ions has the higher melting point- Clicker Questionso The name of the compound NH4NO3 is…A. ammonia nitrateB. Ammonia nitrideC. Ammonium nitriteD. Ammonium nitrateo What is the most likely charge of an ion of potassium?A. -2B. -1C. +1 (correct) D. +2E.
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