KNEWTON’S Exam with Questions Solved
100% Correct |Verified Answers
VSEPR theory considers electron-pair repulsions in that it predicts molecular structure
based on electron pairs minimizing their repulsions from each other in order to
achieve the most stable structure.
According to VSEPR theory, electrons in the valence shell of a central atom form
__________.
bonding pairs of electrons
lone pairs
both lone pairs and bonding pairs of electrons
,neither lone pairs nor bonding pairs of electrons - Answer both lone pairs and bonding
pairs of electrons
Which of the following is very reactive and can readily combine with
molecules containing atoms with lone pairs?
hypervalent molecues
odd-electron molecules
electron-deficient molecules
all of the above - Answer electron-deficient molecules
Electron-deficient molecules that do not have filled valence shells can readily
combine with molecules containing atoms with lone pairs.
When drawing a Lewis structure for a free radical, which type of atom is more likely
to receive the unpaired electron?
the more electronegative element
the less electronegative element
the heavier element
the lighter element - Answer the less electronegative element
A more electronegative element is more likely to be surrounded by more electrons and
fulfill its octet. A less electronegative element is more likely to have the electron
deficiency, in this case the unpaired electron. Recall that free radicals are electron
deficient and display the same stability trends as electron deficient cations, like
carbocations.
A sulfur atom can make up to ____ bonds in a Lewis structure. - Answer 6
, With six valence electrons, sulfur can make a maximum of six bonds.
Which of the following elements can NOT form hypervalent molecules? (select all
that apply)
N
S
Br
B - Answer N, B
Elements in the second period of the periodic table (n=2) can accommodate only eight
electrons in their valence shell orbitals because they have only four valence orbitals
(one 2s and three 2p orbitals). Elements in the third and higher periods (n≥3) have
more than four valence orbitals and can share more than four pairs of electrons with
other atoms because they have empty d orbitals in the same shell. Therefore, of the
elements listed above boron and nitrogen can not form hypervalent molecules
which molecule is NOT hypervalent?
SF6
PBr3
PBr5
XeF6 - Answer PBr3
Phosphorus can make hypervalent compounds, but in this specific example it is
sharing three bonds and has one lone pair, so it has simply a full octet. SF6 has a sulfur
atom surrounded by 6 fluorine atoms, PBr5 has a phosphorous atom surrounded by 5
bromine atoms, and XeF6 has a xenon atom surrounded by 6 fluorine atoms, all of
100% Correct |Verified Answers
VSEPR theory considers electron-pair repulsions in that it predicts molecular structure
based on electron pairs minimizing their repulsions from each other in order to
achieve the most stable structure.
According to VSEPR theory, electrons in the valence shell of a central atom form
__________.
bonding pairs of electrons
lone pairs
both lone pairs and bonding pairs of electrons
,neither lone pairs nor bonding pairs of electrons - Answer both lone pairs and bonding
pairs of electrons
Which of the following is very reactive and can readily combine with
molecules containing atoms with lone pairs?
hypervalent molecues
odd-electron molecules
electron-deficient molecules
all of the above - Answer electron-deficient molecules
Electron-deficient molecules that do not have filled valence shells can readily
combine with molecules containing atoms with lone pairs.
When drawing a Lewis structure for a free radical, which type of atom is more likely
to receive the unpaired electron?
the more electronegative element
the less electronegative element
the heavier element
the lighter element - Answer the less electronegative element
A more electronegative element is more likely to be surrounded by more electrons and
fulfill its octet. A less electronegative element is more likely to have the electron
deficiency, in this case the unpaired electron. Recall that free radicals are electron
deficient and display the same stability trends as electron deficient cations, like
carbocations.
A sulfur atom can make up to ____ bonds in a Lewis structure. - Answer 6
, With six valence electrons, sulfur can make a maximum of six bonds.
Which of the following elements can NOT form hypervalent molecules? (select all
that apply)
N
S
Br
B - Answer N, B
Elements in the second period of the periodic table (n=2) can accommodate only eight
electrons in their valence shell orbitals because they have only four valence orbitals
(one 2s and three 2p orbitals). Elements in the third and higher periods (n≥3) have
more than four valence orbitals and can share more than four pairs of electrons with
other atoms because they have empty d orbitals in the same shell. Therefore, of the
elements listed above boron and nitrogen can not form hypervalent molecules
which molecule is NOT hypervalent?
SF6
PBr3
PBr5
XeF6 - Answer PBr3
Phosphorus can make hypervalent compounds, but in this specific example it is
sharing three bonds and has one lone pair, so it has simply a full octet. SF6 has a sulfur
atom surrounded by 6 fluorine atoms, PBr5 has a phosphorous atom surrounded by 5
bromine atoms, and XeF6 has a xenon atom surrounded by 6 fluorine atoms, all of
