CHM 1045 Lab Exam Questions and
Correct Answers | Latest Update | A+
covalent bonds form based on
Ans:the sharing of electrons that provides an octet of electrons for each
most energetically stable elements in the periodic table
Ans:noble gases
noble gases are also referred to as
Ans:inert gases
octet rule
Ans:all atoms should strive to have 8 electrons in their outermost shell to achieve the most
energetically stable state
valence electrons
Ans:electrons found in the highest energy shell of an atom (aka the highest principle quantum
number, n, shell)
,core electrons
Ans:electrons corresponding with the closest previous noble gas (i.e. all except those in the
highest energy shell, inner shell electrons)
which group does not typically form ions?
Ans:group 4A, the energy required to add or remove electrons is too great so they achieve the
octet rule by covalent sharing
5 steps of creating a Lewis structure
Ans:1. calculate total number of valence electrons available
2. determine which will be the central atom
3. arrange atoms symmetrically around the central atom
4. place bonds/electrons around the atoms until the octet rule is satisfied for each atom, using
double or triple bonds if necessary
5. show any charges on the molecule by using brackets and writing the charge in the top right
corner outside the brackets
the central atom in a molecule is usually
Ans:the least electronegative atom, often the atom that will allow you to draw the most
symmetrical molecule
,purpose of hybridization
Ans:creates identical bonds instead of some being shorter and stronger than others
unhybridized p orbitals form
Ans:pi bonds for double bonding
two groups attached to a central atom
Ans:sp hybridization
180 degree bond angle
linear electron pair geometry
three groups attached to a central atom
Ans:sp2 hybridization
120 degree bond angles
trigonal planar electron pair geometry
four groups attached to a central atom
Ans:sp3 hybridization
109.5 degree bond angles
tetrahedral electron pair geometry
, five groups attached to a central atom
Ans:sp3d hybridization
120 and 90 degree bond angles
trigonal bipyramidal EPG
six groups attached to a central atom
Ans:sp3d2 hybridization
90 degree bond angles
octahedral EPG
VSEPR
Ans:Valence Shell Electron Pair Repulsion theory
theory of molecular structure that assumes that the atoms of a molecule will spread out
around the central atom and conform to a structure that minimizes the repulsion between their
electrons
why does EPG sometimes differ than molecular geometry?
Ans:lone pairs serve as place holders according to VSEPR, maintaining EPG, but we can't
actually see this when looking at molecular geometry
Correct Answers | Latest Update | A+
covalent bonds form based on
Ans:the sharing of electrons that provides an octet of electrons for each
most energetically stable elements in the periodic table
Ans:noble gases
noble gases are also referred to as
Ans:inert gases
octet rule
Ans:all atoms should strive to have 8 electrons in their outermost shell to achieve the most
energetically stable state
valence electrons
Ans:electrons found in the highest energy shell of an atom (aka the highest principle quantum
number, n, shell)
,core electrons
Ans:electrons corresponding with the closest previous noble gas (i.e. all except those in the
highest energy shell, inner shell electrons)
which group does not typically form ions?
Ans:group 4A, the energy required to add or remove electrons is too great so they achieve the
octet rule by covalent sharing
5 steps of creating a Lewis structure
Ans:1. calculate total number of valence electrons available
2. determine which will be the central atom
3. arrange atoms symmetrically around the central atom
4. place bonds/electrons around the atoms until the octet rule is satisfied for each atom, using
double or triple bonds if necessary
5. show any charges on the molecule by using brackets and writing the charge in the top right
corner outside the brackets
the central atom in a molecule is usually
Ans:the least electronegative atom, often the atom that will allow you to draw the most
symmetrical molecule
,purpose of hybridization
Ans:creates identical bonds instead of some being shorter and stronger than others
unhybridized p orbitals form
Ans:pi bonds for double bonding
two groups attached to a central atom
Ans:sp hybridization
180 degree bond angle
linear electron pair geometry
three groups attached to a central atom
Ans:sp2 hybridization
120 degree bond angles
trigonal planar electron pair geometry
four groups attached to a central atom
Ans:sp3 hybridization
109.5 degree bond angles
tetrahedral electron pair geometry
, five groups attached to a central atom
Ans:sp3d hybridization
120 and 90 degree bond angles
trigonal bipyramidal EPG
six groups attached to a central atom
Ans:sp3d2 hybridization
90 degree bond angles
octahedral EPG
VSEPR
Ans:Valence Shell Electron Pair Repulsion theory
theory of molecular structure that assumes that the atoms of a molecule will spread out
around the central atom and conform to a structure that minimizes the repulsion between their
electrons
why does EPG sometimes differ than molecular geometry?
Ans:lone pairs serve as place holders according to VSEPR, maintaining EPG, but we can't
actually see this when looking at molecular geometry
