Chapter 8 Flashcards
Who developed the Lewis Structure Diagram?
G.N. Lewis
Are ionic bonds exothermic or endothermic?
Exothermic
Which is the larger ion in an ionic bond?
Anion, because it gains electrons
Evidence of ionic bond structures
Brittle, high melting point, crystalline, cleaves among smooth lines
A measure of how much stability results in arranging oppositely charged ions in an ionic solid, or the energy required to completely separate one mole of a solid ionic compound into its gaseous ions
Lattice energy
What is lattice energy determined by?
The Born-Haber cycle calculation
Lattice energy increases with:
Increasing charge (Q) of the cations, and decreasing size (d) of the ions
Which group of elements does not follow the octet rule?
Transition elements
What is polarity?
The difference in electronegativity between elements
When losing electrons, which electrons do transition metals lose first?
P or S block electrons, D block electrons only if necessary
For a covalent bond to form, attractions must be ____ than repulsions
Greater
An unshared pair of electrons
Lone pair
When atoms share a pair of electrons
Bonding pairs
One pair of electrons shared
Single bonds
2 pairs of electrons shared
Double bonds
3 pairs of electrons shared
Triple bonds
A measure of how equally or unequally the electrons in a covalent bond are shared
Bond polarity
Covalent bonds that share electrons equally
Nonpolar covalent bonds
Covalent bonds that unequally share electrons, as one of the atoms attracts electrons more
Polar covalent bonds
The ability of an atom in a molecule to attract electrons to itself
Electronegativity
The greater the difference in electronegativity, _____________
The more polar the bond
Forms when 2 electrical charges of equal magnitude but opposite signs are separated by distance
Dipole
A measurement of the separation of two opposite electrical charges
Dipole moment
The charge an atom would have if all of the electrons in a covalent bond were shared equally
Formal charge
What is the formula for formal charge?
(valence electrons) - 1/2(bonding electrons) - (all nonbonding electrons)
What constitutes a dominant Lewis structure?
The one in which formal charges are closest to zero, or where a charge is put on the most electronegative atom
Multiple structures that can be used to describe a molecule
Resonance structures
Electrons that are specifically on one atom or shared between two atoms
Localized electrons
Electrons shared by multiple atoms
Delocalized electrons
Three types of ions or molecules that don’t follow the octet rule
- Odd number of electrons
- Less than an octet
- More than 8 valence electrons (expanded octet)
Which elements have less than an octet?
Elements in the second period before carbon
H, Be, B
What is a hypervalent element?
An element in periods 3-6 that can use d-orbitals to make more than 4 bonds
Single bonds are:
Longest and weakest
Double bonds are:
Shorter and stronger
Triple bonds are:
Shortest and strongest
