Chapter 9 General Chemistry
Chapter 9 General Chemistry CHEM 1411
Lone Star College-CyFair
Popular in General Chemistry I
Popular in Chemistry
MKTG - 45082 - 001
verified elite notetaker
verified elite notetaker
THEA 1300 (Theatre, Kathryn Wagner, Period Styles of Design)
verified elite notetaker
verified elite notetaker
verified elite notetaker
This 13 page Class Notes was uploaded by Cassandra Danhof on Thursday October 6, 2016. The Class Notes belongs to CHEM 1411 at Lone Star College-CyFair taught by Prof. Chakranarayan in Fall 2016. Since its upload, it has received 2 views. For similar materials see General Chemistry I in Chemistry at Lone Star College-CyFair.
Reviews for Chapter 9 General Chemistry
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 10/06/16
General Chemistry Chapter 9: Ionic and Covalent Bonding Learning Objectives Important Term 9.1 Describing Ionic Bonds Define ionic bond Chemical Bond: A strong attractive ● An ionic bond forms when one or more force that exists between certain are transferred from the valence shell of one atoms in a substance atom to the valence shell of another atom Ionic Bond: A chemical bond ● Cations are elements that lose electrons formed by the electrostatic and therefore become positively charged attraction between positive and ● Anions are elements that gain electrons negative ions and therefore become negatively charged Lewis electrondot symbol: A 1 2 5 ● Ex. Na([Ne]3s )+Cl([Ne]3s 2 p ) symbol in which the electrons in −¿([Ne]3s 3p ) 6 the valence shell of an atom or ¿ ion are represented by dots placed → +¿([Ne])¿Cl around the letter symbol of the Na Explain the Lewis electrondot symbol of an atom element kQ 1 2 ● Lewis electrondot symbols show how Coulomb's Law: E= many valence electrons are in each of the r elements Stronger the attractive force, the higher the melting point. Lattice Energy: The change in energy that occurs when an ionic solid separated into gasphase ions ● Ex. ● Carbon: 4 ve Hydrogen: 1 ve Use Lewis symbols to represent bond formation (example 9.1) ● Use Lewis electrondot symbols to represent the transfer of electrons from magnesium to fluorine atoms to form ions with noblegas configurations ● ○ Describe the energetics of ionic bonding ● The energy to remove an electron is the ionization energy ● The energy to add an electron is the electron affinity 9.2 Electron Configuration of Ions State the three categories of monatomic ions of the maingroup elements ● Cations: Have ion charges equal to group numbers ● Cations: Have ion charges equal to group number 2 ● Anions: Have ion charges equal to the group 8 Write the electron configuration and Lewis symbol for a maingroup ion (example 9.2) ● Write the electron configuration and the 3−¿ Lewis symbol for ¿ N ○ The electron configuration of the N atom is 2 3 . By [He]2s 2 p gaining 3 e the atom assumes a 3 charge and the neon configuration 2 6 [He]2s 2 p . The lewis symbol is : ○ Note the polyatomic ions given in table 2.6 Nam Formula Name Form e ula Mercu 2+¿ Permangana MnO 4 ry(I) Hg❑ ¿ te or 2 Mercu rous Amm +¿ Nitrite −¿ onium NH ¿ NO ¿ 4 2 Cyani −¿ Nitrate −¿ de CN ¿ NO ¿ 3 Carbo 2−¿ Hydroxide −¿ nate ¿ OH ¿ CO 3 Hydro −¿ Peroxide ¿ 2−¿¿ gen HCO 3 O 2 carbo nate (or bicarb onate) Acetat −Phosphate C 2 O3❑ 2 ❑ 3−¿ e ¿ PO ¿ 4 Oxala 2−¿ Monohydrog 2−¿ te ❑ ¿ en ¿ C 2 ❑ 4 phosphate HPO 4 Hypoc −¿ ¿ Dihydrogen −¿❑ ¿ hlorite ClO phosphate H 2O ❑ 4 Chlori −¿ ¿ Sulfite 2−¿ te ClO 2 SO ¿ 3 Chlor −¿ Sulfate 2−¿ ate ClO ¿ ¿ 3 SO 4 −¿ −¿ Perchl ¿ Hydrogen ¿ orate ClO 4 Sulfite (or HSO 3 bisulfite) −¿ Chro 2−¿ Hydrogen ¿ mate CrO ¿ Sulfate (or HSO 4 4 bisulfate) −¿ Dichr Cr2O❑ 7❑ Thiosulfate 2−¿ omate ¿ S2O 3 ¿ Note the formation of 2+ and 3+ transitionmetal ions Write electron configurations of transition metal ions (example 9.3) ● Write the electron configuration of 3+¿ ¿ 2+¿∧Fe Fe ¿ ○ 2+¿ is 6 Fe ¿ [Ar]3d ○ 3+¿ is [Ar]3d 5❑ Fe ¿ 9.3 Ionic Radii Define ionic radius Ionic Radius: A measure of the ● The size of the region around the nucleus. size of the spherical region around Changes depending on the shell/v.e the nucleus of an ion within which the electrons are most likely to be found. Isoelectronic: Different species having the same number and configuration of elections Define isoelectronic ions ● Element that have the same number of electrons +¿ ¿ ● Ex. −¿,Ne,Na F¿ Use periodic trends to obtain relative ionic radii (example 9.4) ● Arrange the following ions in order of 2−¿ ¿ 2+¿,O decreasing ionic radius: −¿ , Mg¿ ¿ F 2−¿ ¿ ○ Note that 2+¿,O are −¿,Mg ¿ ¿ F isoelectronic, If you arrange them by increasing nuclear charge, they will be in order of decreasing ionic radius. The −¿,Mg 2+¿ order is ¿ O ¿ ¿ ¿ 9.4 Describing Covalent Bonds Describe the formation of a covalent bond between two Covalent Bond: A chemical bond atoms formed by the sharing of a pair of ● The formation of a covalent bond is the electrons between atoms attractions between two atoms to fill their valencLewis ElectronDot Formula: A electron shell. formula using dots to represent ○ Ex. Hydrogen has 1 valence electrons electron in its 1s orbital. If it adds anothBonding Pair: An electron pair Hydrogen, it will have 2 electrons in its 1sshared between two atoms orbital, filling the orbitals it needs Lone (nonbonding) Pair: An Define Lewiselectron dot formula electron pair that remains on one atoms and is not shared Coordinate Covalent Bond: A bond formed when both electrons of the bond are donated by one atom Octet Rule: The tendency of atoms ● The Lewis electron dot symbol for the in molecules to have eight hydrogen atoms represents the covalent bond by electrons in their valence shells a pair of dots (two for hydrogen atoms) Define bonding pair and lone (nonbonding) pair of Single Bond: A covalent bond in electrons which a single pair of electrons is shared by two atoms Double Bond: A covalent bond in which two pairs of electrons are shared by two atoms Triple Bond: A covalent bond in which three pairs of electrons are shared by two atoms ● Bonding pairs are pairs connected to each element ● Lone Pairs are pairs that are not connected to another element Define coordinate covalent bond ● Where you can get both electrons from the same atom ● Ex ○ State octet rule ● The octet rule is the tendency for molecules to want to fill their valence shell by getting 8 electrons. Define single bond, double bond, and triple bond ● Single Bond: A pair of atoms bonded by 2 electrons ● Double Bond: A pair of atoms bonded by 4 electrons ● Triple Bond: A pair of atoms bonded by 6 electrons 9.5 Polar Covalent Bonds; Electronegativity Define polar covalent bond Polar Covalent Bond: A covalent ● Polar covalent bonds tend to have bond in which the bonding unequal electron spread between them. electrons spend more time near one atom than the other Electronegativity: A measure of the ability of an atom in a molecule to draw bonding electrons to itself ● Ex. Define electronegativity ● An atom’s ability to draw other electrons to itself State the general periodic trends in electronegativities ● In general, electronegativity increases from left to right and from top to bottom in the periodic table Use the electronegativity to obtain relative bond polarity (example 9.5) ● Use electronegativity values to arrange the following bond in order of increasing polarity: PH, HO, CCl ○ P = 2.2 on the Pauling electronegativity scale ○ H = 2.2 ■ Therefore, their bonding electronegativity difference is 0:0 ○ H = 2.2 ○ O = 3.4 ■ Electronegat ivity difference: 1.2 ○ C = 2.6 ○ Cl = 3.2 ■ Electronegat ivity difference: .6 ● The most polar bonds are (in increasing order): PH, CCl, HO 9.6 Writing Lewis Electron Dot Formulas Write Lewis formulas with single bonds only (example 9.6) SCl ● Sulfur dichloride, 2 is a red, fuming liquid used in the manufacture of insecticides. Write the Lewis Formula for the molecule. ○ Calculate the total number of valence electrons ■ S has 6 valence electrons ■ Cl has 7 valence electrons (x2 makes 14 valence electrons) ○ Write the skeleton structure with two electrons to each bonds between atoms ■ You would but the S atom in the middle, since the S atom has 2 electrons it needs, while the 2 Cl atoms only need 1 ■ ○ Distribute electrons to the outer atoms to satisfy the octet rule ○ Write Lewis formulas having multiple bonds (example 9.7) ● Carbonyl Chloride, or phosgene COCl 2 , is a highly toxic gas used as a starting material for the preparation of polyurethane plastics. What is the electron dot formula for COCl 2 ? ○ Calculate the total number of valence electrons ■ C = 4 ve ■ O = 6 ve ■ Cl = 7 ve (x2) = 14 ve ● T otal: 24 ve ○ Write the skeleton structure with two electron bonds between atoms ○ ○ Distribute electrons to the outer atoms to satisfy the octet rule ○ ○ This only satisfies up to 6 electrons, so we have to take electrons from another pair of electrons to make a doublepair. ○ ○ This fulfills the octet rule 9.7 Delocalized Bonding; Resonance Define delocalized bonding Delocalized Bonding: A type of ● Delocalized bonding is the fact that bonding in which a bonding pair of electrons are actually spread over a region of the electrons is spread over a number atoms bonded instead of just in pairs. of atoms rather than localized between two Resonance Description: You describe the electron structure of a molecule having delocalized bonding by writing all possible electrondot formulas ● Ex. Define resonance description ● ● It’s where you write the resonance formula in all of the possible ways it could be said Write resonance formulas (example 9.9) ● Write at least one electrondot formula for a molecule or ion. If the formula as both single and multiple bonds, note whether it’s possible to write other electrondot formulas differing only in the placement of single and double bonds ● Carbonate Ion: ● 9.8 Exceptions to the Octet Rule Note the exceptions to the octet rule in Group IIA and Group IIIA elements ● There are 3 exceptions to the octet rule: a. Molecules, such as NO with an odd number of electrons b. Molecules in which 1 or more atoms possesses more than 8 electrons, such as SF 6 c. Molecules where atoms have less than 8 electrons, like BCl 3 9.9 Formal Change and Lewis Formulas Define formal change Formal Change: The hypothetical ● The formula charge gives you the best charge you obtain by assuming approximate distribution of electrons in the that bonding electrons are equally molecules shared between bonded atoms State the rules for obtaining formal change and that the elections of each lone 1. Half of the electrons of a bond are pair belong completely to one assigned to each atom in the bond (counting atom each dash as two electron) 2. Both electrons of a lone pair are assigned to the atom to which the lone pair belongs State three rules useful in writing Lewis formulas ● Whenever you can write several Lewis formulas for a molecule, choose the one having the lowest magnitudes of formal changes ● When proposed Lewis formulas for a molecule have the same magnitudes of formal charges, choose the one having the negative formal charge on the more electronegative atom ● When possible, choose Lewis formulas that do not have like charges on adjacent atoms 9.10 Bond Length and Bond Order Define bond length Bond Length (Bond Distance): The ● The distance between the different atom’s distance between the nuclei in a nuclei in a bond. bond ● This can help determine the type of Covalent Radii: The value for that bonding present atom in a set of covalent radii Define covalent radii assigned to atoms in such a way 1. WIthin a period, the covalent radius tends that the sum of the covalent radii to decrease with increasing atomic number of atoms A and B predicts the 2. Within a group, the covalent radius tends approximate AB bond length to increase with period number Bond Order: The number of pairs Define bond order of electrons in a bond ● The number of pairs of electrons in a bond. For example, a single bond is a bond order 1, while a double bond is a bond order 2 Explain how bond order and bond length are related (example 9.12) ● Consider the molecules ❑ N 2 ,4 ,∧2 F❑ 2 2 . Which molecule has the strongest nitrogennitrogen bond? Which has the longest nitrogennitrogen bond? ○ First. Write the Lewis formulas ○ N 2 4 ○ N 2 ○ N F❑ ❑ 2 2 ● The nitrogennitrogen bond should be the in N because it has a triple bond, then 2 N 2 2 which has a double bond, and the longest N 2 4 which has a single bond 9.11 Bond Enthalpy Define bond enthalpy Bond Enthalpy: The average ● enthalpy change for the breaking Estimate Δ H from bond enthalpies (example 9.13) on an AB bond in a molecule in the gas phase
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'