Chapter 8 Flashcards
What is Ionic Bonding?
Type of bonding where electrons are transferred from a metal ion to a non metal ion
Ionic bonding is based on?
differences in electronegativity and
ionization energy
What is Coulomb’s Law used for?
to calculate the amount of energy that is involved in the interaction between a pair of ions
In coulomb’s law, a negative sign indicates?
an attractive force between the ions
Columb’s law tells us that?
the ion pair has lower energy when bonded than individual ions.
the closer the pair is when bonded, the more _____ the process is.
exothermic
Columb’s law can also be used to calculate?
the repulsive forces between like charged atoms
In case of diatomic molecules, we can use Columb’s law to?
find the exact spot where bond energy favors formation of a chemical bond
What is Bond length?
the distance at which energy in the system is at a minimum
All systems will bond in a way that?
maximizes the attractive forces and minimizes the repulsive forces between atoms/ions
At short distances the repulsive forces _____? Why?
increase because of the closeness of the particles
At large distances the repulsive forces _____? Why?
decrease because atoms are unable to bond
What are Covalent Bonds?
bonds formed when non-metals share electrons
In a covalent bond, electrons are?
shared equally or unequally
if electrons are shared equally the bond is?
non-polar
If electrons are shared unequally the bond is?
polar
all polar covalent molecules will have?
partial charges
Partial charges means?
there is a positive and negative pole
What is electronegativity?
the ability of an atom to attract electrons to itself.
The ability of an atom to attract electrons to itself, is based on?
nuclear strength
Metals electronegativity values are _____.
low
Non-metals electronegativity values are ________.
high
Greater electronegativity difference between bonding elements leads to?
a less covalent bond, and more ionic bond
Instead of the regents electronegativity values we use?
% ionic character
If a compound is able to
conduct an electric current when melted, its?
ionic
generally the % ionic character is?
greater than 50%
what are Dipolar molecules?
Molecules with a slight negative end,
and a slight positive end
why do Dipolar molecules have a slight negative end and a slight positive end?
a difference in electronegativity values between atoms
In an electric field, dipolar molecules will do what?
orient themselves
How are molecules with polar bonds but no dipole oriented?
oriented so charge differences are equally distributed over the entire molecule
In a molecule with polar bonds but no dipole, what happens to the charges?
the charge differences are cancelled out
In a molecule with polar bonds but no dipole, no one end of the molecule is?
greater in charge than the other
What types of molecules follow the rule associated with molecules with polar bonds but no dipole?
Linear, tetrahedral, and planar molecules
What is the rule associated with molecules with polar bonds but no dipole?
charge differences are equally distributed over the whole molecule
Group 1 always ______.
loses one electron
Group 2 always ______.
loses two electrons
Group 16 mostly _____.
gains 2 electrons
Group 17 mostly ______.
gains 1 electron.
Anions gain what?
electrons
What charge do anions have?
negative
How does an anions radius change?
It is larger than the atom before it
Cations lose what?
electrons
What charge does a cation have?
positive
How does a cations radius change?
It is smaller than the atom before it.
Why are cations significantly smaller?
they lose an entire energy level when bonding
What does the Isoelectronic Series involve?
Ions that have the same number of electrons when done with a reaction
All ions in the Isoelectronic series have?
the same noble gas configuration when bonded to another atom
What happens to the size across a isoelectronic series?
decreases
What happens to the nuclear charge across a isoelectronic series?
increases
As you go up the periodic table, electronegativity _______
increases
As you go across the periodic table, electronegativity______
increases
What is polarity?
An entity containing two distinct and opposite poles that can either attract or repel each other
As attractive forces in the system are maximized, what happens to the PE?
it decreases
when bonds are broken, the energy change is?
positive
when bonds are formed, the energy change is?
negative
breaking of bonds is _______.
endothermic
formation of bonds is __________.
exothermic
Strengths of the bond model (3)
- Associates energy with the formation of bonds between elements
- Shows relationships between atoms in a molecule
- Visual tool to understanding chemical structure
Weaknesses of the bond model (2)
- bonds are not physical structures
- Can not explain some of the behavior we observe in molecules
Single bonds are the ______ bond
weakest
Double and triple bonds are the _______ bonds
strongest
Why are double and triple bonds so strong?
The bond lengths are shorter
3 assumptions of lone electron pairs
- can be accurately drawn with Lewis dot diagram
- structure we draw is accurate of the geometry of the model
- We can illustrate the shape/ bending of a molecule
number of electron pairs around a Linear atom?
B:2 L:0
What are the 2 names of the electrons around a central atom?
Bonding and Lone
number of electron pairs around a Trigonal Planar atom?
B:3 L:0
number of electron pairs around a Trigonal Planar Bent or V shape atom?
B:2 L:1
number of electron pairs around a Tetrahedral atom?
B:4 L:0
number of electron pairs around a Trigonal Pyramidal atom?
B:3 L:1
number of electron pairs around a Bent or V shaped Tetrahedral atom?
B:2 L:2
number of electron pairs around a Trigonal Bipyramidal atom?
B:5 L:0
number of electron pairs around a Seesaw atom?
B:4 L:1
number of electron pairs around a T-shaped atom?
B:3 L:2
number of electron pairs around a Linear Trigonal bipyramid atom?
B:2 L:3
number of electron pairs around a Octahedral atom?
B:6 L:0
number of electron pairs around a square pyramidal atom?
B:5 L:1
number of electron pairs around a Square Planar atom?
B:4 L:2
Linear geometry has how many electrons
2
Trigonal planar has how many electrons
3
Tetrahedral has how many electrons
4
Trigonal bipyramidal has how many electrons
5
Octahedral has how many electrons
6
Bond angle of linear
180
Bond angle of Bent or V shaped Trigonal planar
slightly less than 120
Bond angle of Trigonal planar
120
Bond angle of tetrahedral
109.5
Bond angle of Trigonal pyramidal
107.5
Bond angle of Bent or V shaped tetrahedral
104.5
Bond angle of Trigonal Bipyramidal
120 in plane, 90 perpendicular to plane
Bond angle of Seesaw
Complex
Bond angle of T shaped
Approx. 90
Bond angle of Linear Trigonal bipyramid
180
Bond angle of Octahedral
90
Bond angle of Square Pyramidal
Approx. 90
Bond angle of Square Planar
90
Atoms that are linear
linear, Trigonal bipyramid
Atoms that are Trigonal planar
Bent or V-shaped, Trigonal Planar
Atoms that are tetrahedral
tetrahedral, trigonal pyramidal, Bent or V-shaped
Atoms that are Trigonal bipyramidal
Trigonal bipyramidal, Seesaw, T-shaped, Linear
Atoms that are Octahedral
Octahedral, Square Pyramidal, square planar
What are the diatomic molecules?
Hydrogen, Nitrogen, Fluorine, Oxygen, Iodine, Chlorine, and Bromide
duet rule
hydrogen, helium, lithium, beryllium, and boron form stable molecules when they share 2 electrons
Octet Rule
elements carbon and beyond form stable molecules when they are surrounded by 8 electrons
Exceptions to the octet rule
Boron Triflouride and Sulfur Hexafluoride
molecules with dipolar moment are ______
polar
molecules without a dipole moment are _______
nonpolar
Resonance
More than 1 valid structure exists for a molecule
Where is resonance usually found?
polyatomic ions
a bond will form if the energy in a system can?
lower its total energy
the simultaneous attraction of each electron by the protons generates a force that?
balances the proton- proton and electron- electron repulsive forces at the distance corresponding to bond length.
unequal sharing of electrons results in a ________ bond.
polar covalent
dipole moments
when a molecule has a center of positive charge and a center of negative charge
atoms in a stable compound have a _________ configuration.
noble gas
In Isoelectronic ions, what determines the size?
number of protons
For a series of isoelectronic ions, as size ____ the nuclear charge ________.
decreases, increases
lattice energy
change in energy that takes place when separated gaseous ions are packed together to form an ionic solid
lattice energy is also defined as?
the energy released when an ionic solid forms from ions
Ionic character ______ with EN difference
increases
bonds result from when?
A system is seeking its lowest possible energy
Localized Electron model
A molecule composed of atoms bound together by sharing electrons using atomic orbitals
electron pairs are assumed to be localized on a particular atom or?
in space between 2 atoms
Lone pairs
pair of electrons localized on the atom
bonding pairs
pair of electrons in the space between atoms
atoms want to achieve _______ configuration
noble gas
second row elements are assumed to always?
obey the octet rule
second row elements never?
exceed the octet rule
Which two elements often have fewer than 8 electrons around them in compounds?
Boron and Beryllium
When writing the Lewis structure for a molecule you do what first?
satisfy the octet rule
formal charge
difference in # of valence electrons and valance electrons assigned to the atom in the molecule
atoms in molecules try to achieve formal charges close to ?
zero
negative formal charges are expected to reside on?
the most electronegative atoms
Sigma bonds have what bonds?
single double and triple
Pi bonds have what bonds?
double and triple
