Chapter 9 Ionic and Covalent Bonding - Weebly

1 Chapter 9 Ionic and Covalent BondingCopyright Cengage Learning. All rights | 2A chemical bondis a strong attractive force that exists between certain atoms in a are three types of chemical bonds: Ionic bondsCovalent bondsMetallic bondsCopyright Cengage Learning. All rights | 3An Ionic bondis a chemical bond formed by the electrostatic attraction between positive and negative Cengage Learning. All rights | 4An Ionic bond forms when one or more electrons are transferred from the valence shell of one atom to the valence shell of another atom.

2 Na ([Ne]3s1) + Cl ([Ne]3s23p5) Na+([Ne]) + Cl-([Ne]3s23p6)The atom that transferred the electron(s) becomes a atom that gained the electron(s) becomes an Cengage Learning. All rights | 5A Lewis electron-dot symbol is a notation in which the electrons in the valence shell of an atom or ion are represented by dots placed around the chemical symbol of the :Dots are placed one to a side, until all four sides are Cengage Learning. All rights | 6 Table illustrates the Lewis electron-dot symbols for second- and third-period Cengage Learning.

3 All rights | 7 Represent the transfer of electrons in forming calcium oxide, CaO, from atoms.+Ca2+CaO+O2-][Copyright Cengage Learning. All rights | 8 Polyatomic ionsare atoms held together by Covalent bonds as a group and that, as a group, have gained or lost one or more electron. Copyright Cengage Learning. All rights | 9A Covalent bondis a chemical bond formed by sharing a pair of Cengage Learning. All rights | 10A formula using dots to represent valence electrons is called a Lewis electron-dot electron pair is represented by two dots.

4 A electron pair that is betweentwo atoms is a Bonding pair. It can also be represented by one line for each Bonding pair. Electron pairs that are not Bonding are nonbonding, or lone pair Cengage Learning. All rights | 11A coordinate Covalent bond is formed when both electrons of the bond are donated by one two electrons forming the bond with the hydrogen on the left were both donated by the nitrogen. Once shared, they are indistinguishable from the other N H ++NHHHNHHHH+Copyright Cengage Learning.

5 All rights | 12In forming Covalent bonds, atoms tend toward having a full eight electrons in their valence shell. This tendency is called the octet is an exception to the octet rule: it has two electrons in its valence shell (a duet).Copyright Cengage Learning. All rights | 13A single bondis a Covalent bond in which one pair of electrons is shared by two double bondis a Covalent bond in which two pairs of electrons are shared by two triple bondis a Covalent bond in which three pairs of electrons are shared by two atoms.

6 Double bonds form primarily with C, N, and O. Triple bonds form primarily with C and Cengage Learning. All rights | 14A polar Covalent bond(or polar bond) is a Covalent bond in which the Bonding electrons spend more time near one atom than near the other atom. Electronegativity,X, is a measure of the ability of an atom in a molecule to draw Bonding electrons to itself. Electronegativity is related to ionization energy and electron Cengage Learning. All rights | 15 Electronegativity increases from left to right and from bottom to top in the periodic table.

7 F, O, N, and Cl have the highest electronegativity Cengage Learning. All rights | 16 The difference in electronegativity between the two atoms in a bond is a rough measure of bond polarity. When the difference is very large, an Ionic bond forms. When the difference is large, the bond is polar. When the difference is small, the bond is Cengage Learning. All rights | 17 Using electronegativities, arrange the following bonds in order by increasing polarity: C N, Na F, O Na F, the difference is (F) (Na) = C N, the difference is (N) (C) = O H, the difference is (O) (H) = N <Bond polarities:O H <Na FCopyright Cengage Learning.

8 All rights | 18 Writing Lewis Electron-Dot Formulas1. Calculate the number of valence Write the skeleton structure of the molecule or Distribute electrons to the atoms surrounding the central atom or atoms to satisfy the octet Distribute the remaining electrons as pairs to the central atom or Cengage Learning. All rights | 19 Write the electron dot formulas for the , hydroxylamineCopyright Cengage Learning. All rights | 20 Count the valence electrons in OF2:O1(6)F2(7)20 valence electronsO is the central atom (it is less electronegative).

9 Now, we distribute the remaining 16 electrons, beginning with the outer atoms. The last four electrons go on Cengage Learning. All rights | 21 Count the valence electrons in NF3:N1(5)F3(7)26 valence electronsN is the central atom (it is less electronegative). Now, we distribute the remaining 20 electrons, beginning with the outer atoms. The last two electrons go on Cengage Learning. All rights | 22 Count the electrons in NH2OH:N1(5)H3(1)O1(6)14 valence electronsN is the central atom. Now, we distribute the remaining six electrons, beginning with the outer atoms.

10 The last two electrons go on Cengage Learning. All rights | 23 Write electron-dot formulas for the following: a. CO2b. HCNC opyright Cengage Learning. All rights | 24 Count the electrons in CO2:C1(4)O2(6)16 valence electronsC is the central atom. Now, we distribute the remaining 12 electrons, beginning with the outer atoms. Carbon does not have an octet, so two of the lone pairs shift to become a Bonding pair, forming double Cengage Learning. All rights | 25 Count the electrons in HCN:H1(1)C1(4)N1(5)10 valence is the central atom.