ch 3. Bonding & Chemical Interactions

less

elements with an incomplete octet are stable with ______ than 8 electrons; include H, He, Li, Be, and B

more

elements with an expanded octet are stable with ______ than 8 electrons; include all elements in period 3 or greater

cannot

compounds with an odd number of electrons ________ have 8 electrons in each element

low, high

ionic bonds are formed via the transfer of one or more electrons from an element with a relatively _____ ionization energy to an element with a relatively _____ electron affinity

electronegativities, 1.7, nonmetals

ionic bonds occur between elements with large differences in _______________ (> ___), usually between metals and ___________

crystalline lattices

ionic compounds form ____________ _________ — large, organized arrays of ions

dissolve

ionic compounds tend to _________ in water and other polar solvents

high

ionic solids tend to have ______ melting and boiling points

lose, cations

In ionic bonds, metals _____ electrons to become ________

gain, anions

In ionic bonds, nonmetals ______ electrons to become ________

electronegativities

a covalent bond is formed via the sharing of electrons between two elements of similar __________________

bond order

refers to whether a covalent bond is a single, double, or triple bond

increases, increases, decreases

As bond order increases, bond strength __________, bond energy __________, and bone length ___________.

electronegativity, electronegativity, 0.5

nonpolar covalent bonds result in molecules in which both atoms have exactly the same ________________; some bonds are considered nonpolar when there is a very small difference in _______________ between the two atoms (< ___)

H, N, O, F, Cl, Br, I

name the 7 naturally occurring diatomic elements that form nonpolar bonds with an atom of the same element

electronegativities, 0.5, 1.7,

polar covalent bonds form when there is a significant difference in ________________ (___ to ___), but not enough to transfer electrons and form an ______ bond.

coordinate covalent bonds

result when a single atom provides both bonding electrons while the other atom does not contribute any; most often found in Lewis acid-base chemistry

Lewis dot structures

a chemical representation of an atom’s valence electrons

valence electrons

the number of dots in a Lewis structure = the number of ________ ________ for that element

valence electrons

Formal charges exist when an atom is surrounded by more or fewer _________ _________ than it has in its neutral state

# of valence electrons - # of dots (lone electrons) - # of sticks (covalent bonds)

formula for calculating an atom’s formal charge

resonance structures

For any molecule with a pi system of electrons, _____________ ____________ exist

resonance structures

these represent all of the possible configurations of electrons (stable and unstable) that contribute to the overall structure

contributes, resonance hybrid

The more stable the resonance structure, the more it ___________ to the character of the ___________ _________

1, 0

A single bond consists of ___ sigma (σ) bond(s) and ___ pi (π) bond(s)

1, 1

A double bond consists of ___ sigma (σ) bond(s) and ___ pi (π) bond(s)

1, 2

A triple bond consists of ___ sigma (σ) bond(s) and ___ pi (π) bond(s)

VSEPR theory

proposes that electrons, whether bonding or nonbonding, arrange themselves to be as far apart as possible from each other in 3D space, leading to characteristic geometries

more

According to the VSEPR theory, nonbonding electrons exert ______ repulsion than bonding electrons because they reside closer to the nucleus

electronic geometry

describes the spatial arrangement of all pairs of electrons around the central atom, including both the bonding and the lone pairs; an important implication of this is in the determination of the ideal bond angle

molecular geometry

describes the spatial arrangement of only the bonding pairs of electrons around the central atom; the coordination number is the relevant factor

coordination number

the number of atoms that surround and are bonded to a central atom

overlap

sigma (σ) and pi (π) bonds describe the patterns of _________ observed when molecular bonds are formed

atomic, molecular

When two atoms bond to form a compound, the _______ orbitals interact to form a ____________ orbital which describes the probability of finding the bonding electrons in a given space

single atom, molecule

Atomic orbitals describe the probable location of electrons around a ________ ______, while molecular orbitals describe the probable location of electrons in a ____________.

sigma bonds

the result of head-to-head overlap; allow for free rotation about the axes

pi bonds

the result of the overlap of two parallel electron cloud densities; do not allow for free rotation about the axes

weaker

are covalent bonds stronger or weaker than ionic bonds?

weaker

are intermolecular forces stronger or weaker than covalent bonds?

London dispersion forces

the weakest of the intermolecular interactions because they are the result of induced dipoles that change and shift moment to moment; present in all atoms and molecules; a type of van der Waals force

increases, large, polarizable

London dispersion forces __________ as the size of the atom or structure increases because ______ molecules are more easily _____________

dipole-dipole interactions

a type of intermolecular force which occurs between the oppositely charged ends of polar molecules; stronger than London forces; these interactions are evident in the solid and liquid phases but negligible in the gas phase due to the distance between particles

hydrogen bonds

a specialized subset of dipole-dipole interactions; occurs when hydrogen is bonded to one of three very electronegative atoms — F, O, or N

high

substances that display hydrogen bonding tend to have unusually ______ boiling points