Chapter 8 Review Flashcards
Bonds tend to form to give . . . electron configurations
more stable
Bond form to give more stable electron configurations by . . .
losing, sharing, and gaining electrons
The three types of bonds are . . .
Ionic bonds, Covalent bonds, and Metallic bonds
Ionic bonds have a . . . of electrons
complete transfer
Because ionic bonds have a complete transfer of electrons, the ions in that bond have . . .
opposite charges
The electrons in covalent bonds are ______
shared
Metallic bonding results in . . .
delocalized valence electrons which are
electrostatically attracted to fixed metal nuclei.
Ionic bonding has . . .
electrostatic attractions (typically between a metal and a nonmetal)
Covalent bonding has . . .
Shared electron pairs (typically between two nonmetals)
Metallic bonding can be referred to as a . . .
“sea of electrons”
The electrons involved in chemical bonding are called . . .
valence electrons
An element’s Lewis symbol consists of . . .
the element’s chemical symbol and a dot for each valence electron
Most ions have a . . . electron configuration
noble gas
A noble gas configuration is . . .
ns^2 np^6
Noble gases have a very ______ electron configuration
stable
The octet rule says that . . .
Atoms tend to lose, gain or share electrons until they are surrounded by 8 valence electrons (full s and p subshells in an atom)
Ions that DO NOT have noble gas configurations are . . .
H, He, and most transition metals
Because H, He, and most transition metals do not have noble gas configurations, they don’t . . .
follow the octet rule
Ionic bonding results from the electron transfer between . . .
positive cations and negative anions
Low ionization energy (metals) =
cations
High electron affinity (nonmetals)=
anions
Some characteristics of Ionic compounds include:
- Hight melting points
- High heats of fusion and vaporization
- Electrical insulators when solid
- Electrical conductors when molten or
dissolved in water - Hard and Brittle
The formation of ionic compounds is
very . . .
exothermic
Ionic compounds are . . .
very stable
The pattern that cations and anions organize themselves in is called a . . .
lattice
A crystal lattice is . . .
an arrangement of ions of opposite charge
surrounding one another in three dimensions
The strong attraction of the cations to anions in a lattice can be measured as . . .
lattice energy
Lattice energy is . . .
the energy (kJ/mol) needed to completely separate 1 mole of a solid ionic compound into its cations and anions
What would an equation for lattice energy of cation X and anion Y look like?
XY(s) –> X(+)(g) + Y(-)(g)
An equation to find lattice energy is . . .
Eel = (kQ1Q2)/d
Lattice energy, crystal stability, and ionic bond strength increase as . . .
Ionic charges (Q1 and Q2) increase or atomic radii (d) decrease
When it comes to lattice energy, between ionic charge and atomic radii, which of those two factors has a greater effect on lattice energy?
Ionic charge
What physical properties does the lattice energy affect?
- Melting Point
- Boiling Point
- heats of fusion (ΔHfus) and vaporization (ΔHvap)
Covalent bonding generally occurs between
nonmetals
Covalent bonds share electrons to try to get a . . . configuration
Noble Gas
Covalent bonds can be represented with . . .
Lewis Symbols
Covalent bonds form by . . .
sharing one or more pairs of electrons
Some characteristics of Covalent molecules are . . .
- Low melting points and boiling points
- Low heats of fusion and vaporization
- Poor conductors of heat and electricity
- More likely to be flammable
- Soft, brittle solids
When a molecular substance melts or boils, the covalent bonds . . .
do not break
when a molecular substance melts or boils, what happens is that . . .
intermolecular interactions are broken
In Lewis structures, shared electrons are drawn as . . .
bonds
In Lewis structures, nonbonding electrons are drawn as . . .
dots
In Lewis structures, the electrons that are able to be shared are . . .
the dots
What happens when atoms form bonds but there’s a “scarcity” of valence electrons?
they form double or triple bonds
To achieve an octet with the available valence electrons, atoms . . .
can share more than one pair of electrons.
A single bond is when
two atoms share one electron pair
A double bond is when
two atoms share two electron pairs
A triple bond is when
two atoms share three electron pairs
A single bond has a bond order of
1
A double bond has a bond order of
2
A triple bond has a bond order of
3
When two atoms collide, but do not bond, the closest distance between the two nuclei is called . . .
the apparent radii
The apparent radii are . . .
the nonbonding atomic radii
When atoms are in a chemical bond, the nuclei are closer together, this radius is referred to as . . .
the bonding atomic radii
When talking about molecular radii, we use . . .
bonding atomic radii
Provided we know the bonding atomic radii of two elements, we can calculate . . . between those two atoms within a molecule.
the bond length
Bond strengths and bond lengths contribute to . . .
reactivity and thermodynamics
Bond Enthalpy is also symbolized by . . .
D
Bond Enthalpy is . . .
the enthalpy change (ΔH) for the breaking of a particular bond in one mole of a gaseous substance
Since breaking bonds REQUIRES energy, bond enthalpies are always . . .
positive qualities
The greater the bond enthalpy, . . .
the stronger the bond
The stronger the bond, . . .
the greater the bond enthalpy
Most reactions proceed with bond breakage and formation are . . .
simultaneous
Bond polarity is . . .
a measure of how equally, or unequally, the electrons in a covalent bond are shared
Bond polarities can be . . .
nonpolar covalent, polar covalent, or ionic
What leads to an unequal sharing of electrons between two atoms?
Differences in electronegativity between the two atoms
In a compound, the atom that pulls the electrons to itself the most is . . .
the most electronegative atom
asymmetric charge distribution results in . . .
polar bond
When two atoms share electrons unequally, a . . . results
bond dipole
A dipole moment is measured in . . .
Debyes
1 Debyes is equal to . . .
3.34 x 10^-34 C*m
To compare and determine bond polarity, . . .
you can use the difference in electronegativity values (ΔEN)
When the difference in electronegativity values is smaller than 0.5, the bond is . . .
usually nonpolar covalent
When the difference in electronegativity values is between o.5 and 1.6, the bond is . . .
usually polar covalent
When the difference in electronegativity values is between 1.6 and 2.0, the bond is . . .
polar covalent if the two atoms are nonmetals and ionic if one of the two atoms is a metal
When the difference in electronegativity values is greater than 2, the bond is . . .
usually ionic
The greater the difference in electronegativity, the larger . . .
the dipole moment
The larger the dipole moment, the
more . . .
polar is the bond
The first step in drawing a Lewis structure
count the number of valence electrons
When counting the number of elections and accounting for a cation, . . .
subtract one electron from the total for each positive charge
When counting the number of electrons and accounting for an anion, . . .
add one electron from the total for each negative charge
The second step in drawing a Lewis structure
Look at the chemical formula and decide which atom is the CENTRAL atom
The central atom is usually . . .
written first and is the least electronegative element
Chemical formulas are often written in the order . . .
the atoms are connected
The third step in drawing a Lewis structure
draw a molecular “skeleton” connecting all outer atoms to the central atom with single lines
The fourth step in drawing a Lewis structure
complete the octets for the all of the outer atoms using lone pairs
Because hydrogen can only make one bond, hydrogen will only have . . .
2 electrons
The fifth step in drawing a Lewis structure
place any excess electrons (as lone pairs) on the central atom
A central atom can have more than eight electrons if it is . . .
in Row 3 of the Periodic Table or below
If there are not enough electrons to give the central atom an octet, then . . .
shift lone pair electrons from outer atoms to form multiple bonds and satisfy the octet rule
The most dominant Lewis structure has . . .
an overall formal charge equal to 0 and when the most electronegative atom has the negative charge
Formal charge is equal to . . .
Number of valence electrons - lines - dots
When multiple correct Lewis structures can be drawn, . . .
the structures are called resonance structures
The different resonance forms represent . . .
delocalized bonding
Resonance indicates . . .
increased stability in the structure
The first exception to the octet rule is . . .
Ions or molecules with an odd number of electrons
The second exception to the octet rule is . . .
Ions or molecules with less than an octet
The third exception to the octet rule is . . .
Ions or molecules with more than eight valence electrons (an expanded octet)
If there is an odd number of valence electrons, one atom, usually the central atom will contain . . .
7 instead of 8 electrons
The 4 atoms that can have less than 8 electrons are . . .
B, Be, H, and Al
B needs _ electrons
6
Be needs _ electrons
4
H needs _ electrons
2
Al needs _ electrons
6
Atoms that can have more than an octet are . . .
Period 3 or below
When atoms have more than 8 electrons, they are called . . .
hypervalent
Hypervalent atoms are usually surrounded by . . .
small, highly electronegative atoms
