Ch. 8 Flashcards Preview

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Flashcards in Ch. 8 Deck (24)
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1
Q

metallic bond

A

bonds present in metals

  • nuclei immersed in a sea of e-
  • not important
2
Q

types of bonds

A

(1) ionic bond
(2) covalent bond
(3) metallic bond

3
Q

octect rule

A

atoms gain, lose or share e- to achieve full outershell octet of valence e-

4
Q

ionic bond

A

opposing charged ions attract via electrostatic force

- greater charge, greater attraction

5
Q

lattice energy (Eel)

A

energy of ionic bond

Eel = kQ1Q2/d

Q1 - positive ion charge
Q2 - negative ion charge
d - sum of ionic radii

6
Q

lattice energy rules

A

(1) small = greater lattice energy, stronger attraction
(2) higher charge = greater lattice energy
(3) look at charges first, less is better
(4) if same charge, look at atomic radii (smaller = higher)

7
Q

covalent bond

A

sharing of e- btwn similar elemental compounds

8
Q

electronegativity

A

atom tendency to attract or pull e- towards it

  • related to polarity
  • higher bp = higher Zeff
  • fluorine = greatest Zeff
9
Q

terms describing polarity / bonds

A

a bond…

  • is polar
  • has dipole moment
  • has a dipole
  • is polarized
10
Q

electronegativity rules

A

if difference equals

  • 2 or more, ionic
  • 1.9 - 0, polar covalent
  • 0, nonpolar covalent
11
Q

bond polarity

A

describes unequal e- sharing in a bond

  • nonpolar covalent bond
  • polar covalent bond
12
Q

nonpolar covalent bond

A

e- shared equally btwn atoms

13
Q

polar covalent bond

A

one atom exerts > attraction for e- than other

14
Q

dipole

A

magnitude of dipole moment
- one end negative charge, other end positive charge

polarity

15
Q

dipole moment

A

measure of separation & magnitude of +/- charges

  • debyes (D)
  • high charge = more
  • more distance = more
16
Q

resonance

A

case where 2 or more Lewis structures are equally good descriptions of a single molecule
- actual = average, hybrid or blend of resonance structures

17
Q

exceptions to octet rule

A

(1) odd # e-
(2) < # e- of full octet
(3) > # e- of full octet

18
Q

formal charge

A

method of assigning apparent charge to each atom in a Lewis structure
- used to determine which resonance structure is most likely to exist

19
Q

steps to determine formal charge

A

(1) determine # valence e- for atom
(2) subtract # nonbonding e-
(3) subtract # bonds

20
Q

formal charge rules

A

(1) formal charge close to/of 0 = favored
(2) formal charge of ±2 ≠ favored
(3) neg. charge tends to reside on electronegative atoms

21
Q

oxianion

A

polyatomic ion containing O w/ neg. net charge
- may combine w/ cation to form an ionic compound

(ie) SO4, NO3 & CO3

22
Q

bond length determined by

A

(1) bond order - single, double, triple, etc. bonds

(2) atoms involved

23
Q

bond length rules

A

(1) less bond order, greater bond length
(2) less bond length, higher bond energy
(3) less bond length, less ∆H to break/make bond

24
Q

estimating ∆Hrxn using bond energies

A

∆Hrxn = ∈ ∆H (bond breaking) + ∈ ∆H (bond making)