CHAPTER ONE Chemical Bonding PROBLEM 1.3 Which of the following ions possess a noble gas electron config- uration? (a)K (c)H (f)Ca2 SAMPLE SOLUTION (a)Potassium has atomic number 19, and so a potassium atom has 19 electrons. The ion k therefore. has 18 electrons the same as the noble gas argon. The electron configurations of k and Ar are the same 252p63523p Transfer of an electron from a sodium atom to a chlorine atom yields a sodium cation and a chloride anion, both of which have a noble gas electron configuration Na(g) ci(g) Sodium atom Chlorine atom Were we to simply add the ionization energy of sodium (496 kJ/ mol) and the electron affinity of chlorine(-349 kJ/mol), we would conclude that the overall process is endothermic with AH =+147 kJ/mol. The energy liberated by adding an electron to by the German physicist Wal. chlorine is insufficient to override the energy required to remove an electron from ter Kossel in 1916, in order sodium. This analysis, however, fails to consider the force of attraction between the to explain the ability of sub- oppositely charged ions Na and CI, which exceeds 500 kJ/mol and is more than suf- de to conduct an electric ficient to make the overall process exothermic. Attractive forces between oppositely charged particles are termed electrostatic, or coulombic, attractions and are what we mean by an ionic bond between two atoms PROBLEM 1. 4 What is the electron configuration of c of c Does either one of these ions have a noble gas(closed-shell)electron configuration? onic bonds are very common in inorganic compounds, but rare in organic ones. The ionization energy of carbon is too large and the electron affinity too small for car- bon to realistically form a C4+ or C4- ion. What kinds of bonds, then, link carbon to other elements in millions of organic compounds? Instead of losing or gaining electrons, carbon shares electrons with other elements (including other carbon atoms) to give wha are called covalent bonds 1.3 COVALENT BONDS The covalent, or shared electron pair, model of chemical bonding was first suggested Gilbert Newton Lewis (born by G. N. Lewis of the University of California in 1916. Lewis proposed that a sharing of two electrons by two hydrogen atoms permits each one to have a stable closed-shell eley, Califor- electron configuration analogous to helium nia, 1946)has been called he greatest American 984is H: H ue of the journal of chemi. cal Education contains fi Two hydrogen atoms. Hydrogen molecule: articles describing Lewis'life each with a single alent bonding by way of and contributions to chem. electron a shared electron pair Back Forward Main MenuToc Study Guide ToC Student o MHHE WebsitePROBLEM 1.3 Which of the following ions possess a noble gas electron config￾uration? (a) K (d) O (b) He (e) F (c) H (f) Ca2 SAMPLE SOLUTION (a) Potassium has atomic number 19, and so a potassium atom has 19 electrons. The ion K, therefore, has 18 electrons, the same as the noble gas argon. The electron configurations of K and Ar are the same: 1s 2 2s 2 2p6 3s 2 3p6 . Transfer of an electron from a sodium atom to a chlorine atom yields a sodium cation and a chloride anion, both of which have a noble gas electron configuration: Were we to simply add the ionization energy of sodium (496 kJ/mol) and the electron affinity of chlorine (349 kJ/mol), we would conclude that the overall process is endothermic with H° 147 kJ/mol. The energy liberated by adding an electron to chlorine is insufficient to override the energy required to remove an electron from sodium. This analysis, however, fails to consider the force of attraction between the oppositely charged ions Na and Cl– , which exceeds 500 kJ/mol and is more than suf- ficient to make the overall process exothermic. Attractive forces between oppositely charged particles are termed electrostatic, or coulombic, attractions and are what we mean by an ionic bond between two atoms. PROBLEM 1.4 What is the electron configuration of C? Of C? Does either one of these ions have a noble gas (closed-shell) electron configuration? Ionic bonds are very common in inorganic compounds, but rare in organic ones. The ionization energy of carbon is too large and the electron affinity too small for car￾bon to realistically form a C4 or C4 ion. What kinds of bonds, then, link carbon to other elements in millions of organic compounds? Instead of losing or gaining electrons, carbon shares electrons with other elements (including other carbon atoms) to give what are called covalent bonds. 1.3 COVALENT BONDS The covalent, or shared electron pair, model of chemical bonding was first suggested by G. N. Lewis of the University of California in 1916. Lewis proposed that a sharing of two electrons by two hydrogen atoms permits each one to have a stable closed-shell electron configuration analogous to helium. H Two hydrogen atoms, each with a single electron H Hydrogen molecule: covalent bonding by way of a shared electron pair H H Na(g) ±£ Sodium atom NaCl(g) Sodium chloride Cl(g) Chlorine atom  12 CHAPTER ONE Chemical Bonding Ionic bonding was proposed by the German physicist Wal￾ter Kossel in 1916, in order to explain the ability of sub￾stances such as sodium chlo￾ride to conduct an electric current. Gilbert Newton Lewis (born Weymouth, Massachusetts, 1875; died Berkeley, Califor￾nia, 1946) has been called the greatest American chemist. The January 1984 is￾sue of the Journal of Chemi￾cal Education contains five articles describing Lewis’ life and contributions to chem￾istry. Back Forward Main Menu TOC Study Guide TOC Student OLC MHHE Website