Chapter 4 - Chemical Bonding

Covalent bonds

Covalent bonds

________ vibrate slightly, causing stretching and building that can cause the absorption of infrared radiation.

Carbon dioxide

________ is especially good at trapping heat because it absorbs infrared radiation because of the unequal sharing of electrons within its bonds.

Electronegativity

________: an atoms tendency to attract electrons toward itself in a chemical bond.

Delocalization

________: spreading out of electron density over multiple atoms, reducing the potential energy of electrons, therefore lowering the energy of the molecule (resonance stabilization)

Lewis

________ symbols: depict an atoms bonding capacity- the number of bonds an atom typically forms to complete its octet.

third row

Expanded Octet: nonmetals in ________ and below, such as P, S, Xe, etc.

Allotropes

________: different molecular forms of the same element, with different physical and chemical properties.

Dipole

a pair of opposite charges separated by a distance; arrow points towards the more negative, electron- rich end of the bond

Lewis structure

________: two- dimensional representation showing how atoms connect.

Free radicals

________: compounds containing unpaired valence electrons, tend to be very reactive to try to acquire or share an electron.

second element

Add prefix hydro- to the name of the ________ in the formula.

HNO2

________ is nitrous acid, HNO3 is nitric acid.

Oxoanion

________ with the most oxygen has prefix per- and suffix- ate; ________ with fewest oxygens has prefix hypo- and suffix- ite.

Anion

________: name of parent element ending in- ide.

SO2

________ is sulfur dioxide.

NaCl

________ is sodium chloride.

Formal Charge

________: an unreal charge that assigns electrons to atoms within the molecule.

Bond length

________ is an "average "of the two structures.

element symbol

Consists of the ________ surrounded by dots on all four sides representing the valence electrons; all four sides must have one dot before electrons can be paired.

Single bond

________: two atoms share one pair of electrons.

Triple bond

________: two atoms share three pairs of electrons.

Ideal formal charge

________ is 0 on each element, but if impossible, most negative charge should be on the most electronegative element with formal charges as close to zero as possible.

FC

________= (number of valence electrons)- (number of electrons in lone pairs- number of bonds)

Couloumbic attraction

electrostatic attractions between ions of opposite charge

Lattice Energy (U)

energy released when free, gas-phase ions combine to form one mole of a crystalline solid

Crystal Lattice

ordered 3-D array of particles

Bond length

distance between two nuclei in the bond

Bond energy

amount of energy required to break one mole of bond into two moles of the free atom

Polar Covalent Bond

unequal sharing of electrons between atoms; 2.0> Δχ> 0.4

δ +/

represent the partial electrical charges

total electrical charge

complete transfer of electrons; Δχ> 2.0

Nonpolar Covalent Bond

even distribution of charge, equal sharing of electrons; Δχ> 0.4

Electronegativity

an atoms tendency to attract electrons toward itself in a chemical bond

cation

name of parent element

anion

name of parent element ending in -ide

Octet rule

all atoms except the very smallest (ex

Lewis structure

two-dimensional representation showing how atoms connect

Single bond

two atoms share one pair of electrons

Double bond

two atoms share two pairs of electrons

Triple bond

two atoms share three pairs of electrons

Lone Pairs

pair of electrons that is not shared

Allotropes

different molecular forms of the same element, with different physical and chemical properties

Resonance Structures

2+ Lewis structures with same atomic arrangement but different arrangements of bonding electrons and lone pairs

Delocalization

spreading out of electron density over multiple atoms, reducing the potential energy of electrons, therefore lowering the energy of the molecule (resonance stabilization)

Bond Length

distance between the nuclei of two bonded atoms; depends on atomic identity and number of bonds formed

Bond Order

number of pairs of electrons atoms share

Bond Energy

energy need to break one mole of bonds in the gas phase, always a positive quantity because breaking bonds requires energy; increases as bond order increases

Formal Charge

an unreal charge that assigns electrons to atoms within the molecule

Electron Deficient molecules

Be, B and Al

Free radicals

compounds containing unpaired valence electrons, tend to be very reactive to try to acquire or share an electron

Expanded Octet

nonmetals in third row and below, such as P, S, Xe, etc

symmetric stretch

infrared inactive

asymmetric stretch

infrared active

bending mode

infrared active