Chapter 8 Flashcards
What is the difference between trigonal planar and trigonal pyramidal
trigonal planar doesn’t have lone pairs on the central atom
what group tends to have trigonal planar arrangements
group 3
what group tend to have trigonal bipyramidal arrangements
group 5
What is the electron arrangement of a molecule with 4 e- pairs around the central atom
tetrahedral
What is the electron arrangement
of a molecule with 3 e- pairs around the central atom
trigonal planar
What is the electron arrangement
of a molecule with 2 e- pairs around the central atom
linear
What is the electron arrangement
of a molecule with 5 e- pairs around the central atom
trigonal bipyramidal
What is the electron arrangement
of a molecule with 6 e- pairs around the central atom
octahedral
Geometric arrangement of a molecule with 2 sigma bonds and no lone pair
linear
Why are double and triple bonds considered as one in the VSPER theory
Only sigma bonds are considered and there’s only on in each multiple pair; the other bonds are pi bonds
Geometric arrangement of a molecule with 3 sigma bonds and 0 lone pairs
trigonal planar
Geometric arrangement of a molecule with 2 sigma bonds and 1 lone pair
angular/bent
Geometric arrangement of a molecule with 4 sigma bonds and 0 lone pair
tetrahedral
Geometric arrangement of a molecule with 3 sigma bonds and 1 lone pair
trigonal pyramidal
Geometric arrangement of a molecule with 2 sigma bonds and 2 lone pairs
angular/bent
Geometric arrangement of a molecule with 5 sigma bonds and 0 lone pair
trigonal bipyramidal
Geometric arrangement of a molecule with 4 sigma bonds and 1 lone pair
irregular tetrahedral/see-saw
Geometric arrangement of a molecule with 3 sigma bonds and 2 lone pair
T-shaped
Geometric arrangement of a molecule with 2 sigma bonds and 3 lone pair
linear
Geometric arrangement of a molecule with 6 sigma bonds and 0 lone pair
octahedral
Geometric arrangement of a molecule with 5 sigma bonds and 1 lone pair
square pyramidal
Geometric arrangement of a molecule with 4 sigma bonds and 2 lone pair
square planar
What is the bond angle between 2 e- pairs in a linear arrangement?
180 degrees
What is the bond angle between 3 e- pairs in a trigonal planar arrangement?
120 degrees
What is the bond angle between 4 e- pairs in a tetrahedral arrangement?
109.5 degrees
What is the bond angle between 5 e- pairs in a trigonal bipyramidal arrangement?
90 degrees between the vertical and horizontal plane
120 degrees between the electrons in the horizontal plane
What is the bond angle between 6 e- pairs in an octahedral arrangement?
90 degrees between all pairs
What is the bond angle in a water molecule
104.5 degrees
how does the bond angle change in a molecule with lone pairs and why?
the angle of the respective electron arrangement reduces since lone pairs require more space
Define chemical bond
the strong attractive force between certain atoms in a substance
Whats the difference between an ionic and covalent bond
ionic bonds are formed by a transfer of e- in a cation and anion in a molecule. A covalent bond is formed by sharing a pair of e-
Define bonding pair
electron pair between two atoms, represented by one line
Define lone pair
electron pair that are nonbonding
What rule do atoms obey when forming bonds and why
atoms except hydrogen ten toward the octet rule to become more stable
Define polar covalent bond
unequal sharing of electrons between atoms in molecule=charge separation in bond charge
oriented towards an electric field
Define electronegativity
measure of the ability of an atom to draw bonding electrons to itself
What characteristic is related to electronegativity
ionization energy and electron affinity
Define polar bond
covalent bond where bonding electrons spend more time near one atom than near the other atom
How does electronegativity increase and why
it increases from left to right and bottom to top
what elements are the most electronegative
F, O, N, and CL
What’s the link between polarity and electronegativity? what does it represent
the difference between 2 atoms in a bond = measure of bond polarity
large difference= ionic or polar bond
small difference= nonpolar bond
Define Dipole moment
A molecule whose charge can be represented by center positive and center negative, where a net vector is present
positive center is least electronegative while negative is most electronegative
what do vectors that cancel out mean
no net dipole moment
Are bonds more polar when parallel or perpendicular to the trend
Parallel
How does an anion compare to its parent atom and why?
Anion is bigger since e- is added
How does a cation compare to its parent atom and why?
Cation is smaller, since removal e-
What’s an Isoelectronic series
Serie of ions or atoms containing the same number of electrons
How do you determine the central atom
least electronegative atom is central atom
H\F are never central atoms
what are the exceptions to the octet rule
H has 1 e- pair
C, O, N, F have 4 e- pairs
Be has 2 e- pairs
B, Al, Sn have 3 e- pairs
what conditions need to be respected when distributing the remaining electrons?
H is always surrounded by 2 electrons
Be is always surrounded by 4 e-
B is always surrounded by 6 e-
C, O, N, F are always surrounded by 8 e-
other atoms can have 8 or more e-
Why cant element of the second period expand their octet
they only have s and p orbitals= can’t expand their electron configuration
What do we call more than one valid Lewis structure that can be written for a molecule
resonance structures
How can you obtain the hypothetical charge of an atom
with equation: F=V-B/2-L
How can a molecule be more stable
when all formal charges are similar
True or False
the sum of the formal charges of all atoms in a given molecule/ion must equal to overall charge on that species.
true
Why can e- move around a molecule
they’re delocalized
Are noble gases electronegative?
No
What does VSEPR stand for ?
Valence Shell Electron Pair Repulsion
what are the rules when assigning the formal charges
1) all FC must be similar to have a stable compound
2) the most electronegative electrons must have the most negative FC
3) the structure with the lowest FC in magnitude must be prioritized
4) the sum of all FC must equal the charge of the species
5) FC of an atom must be as close as possible to 0
what molecular arrangement give molecules no net dipole and why is that
linear/ trigonal planar/ tetrahedral
all vectors cancel eachother out
how to achieve a stable compound
make sure that atleast one atom has a noble gas electronic configuration.
whats the trend is ion sizes
for metal: bigger down a group and smaller in a period
for non metals: bigger both ways since add electrons
explain the localized electron model
electron pairs are localized on aparticular atom aka central atom
