Bonding and Chemical Reactions Flashcards

1
Q

Molecules

A

atoms of elements comibing

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2
Q

Chemical Bonds

A

bonds between atoms formed via interaction of valence electrons from both atoms

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3
Q

Octet Rule

A

atoms bond with atoms to form 8 electrons in its outermost shell to resemble the structure of noble gases

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4
Q

Incomplete Octet

A

Hydrogen (2 ve)
Lithium (2 VE)
Beryllium (4VE)
Boron (6VE)

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5
Q

Expanded Octet

A

Any element in period 3 or higher

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6
Q

Odd number of electrons Exception to Octet Rule

A

molecules with odd number of VE cannot distribute electrons to give eight to each atom

ex: NO, nitric ocide

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7
Q

Ionic Bond

A

ELECTRONS from an atom with LOW IONIZATION ENERGY (usually metal) TRANSFER to atom with HIGH ELECTRON AFFINITY (usually nonmetal)

they are held together due to the opposite charges formed between the ions

lattice structures consisting of repeating rows of cations and anions

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8
Q

Covalent Bonding

A

electron pair is SHARED between two atoms, with SIMILAR values of ELECTRONEGATIVITY

usually nonmetals

individually bonded molecules, not lattice structures

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9
Q

Nonpolar vs Polar Covalent Bond vs Coordinate Covalent

A

NonPolar: electron pair is shared equally

Polar: electron pair is shared nonequally

Coordinate: if both shared electrons are contributed by only one of the atoms

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10
Q

Cation

A

atoms that loses electrons, positive charge

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11
Q

Anion

A

atom that gains electrons, negative charge

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12
Q

Ionic Compound Properties

A

Very high melting and boiling points (due to strength of electrostatic force)

Readily dissolve in polar solvents

Good aqueous conductors

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13
Q

Crystalline Lattice of Ionic Bonds

A

repeating units of positive and negative ions to maximize attractive forces and minimize repulsive forces

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14
Q

Energy required to form ions through transfer of electrons is _____ than the energy released forming an ionic bond. Making it ____ to form ions.

A

greater; unfavorable

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15
Q

Covalent compounds contain relatively ___ intermolecular interactions. Leading to the following properties:

A

weak;

Low melting and boiling points
poor conductors in aqueous state

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16
Q

Covalent bonds allow for ___ bonds with other atoms to fill the valence shell of an atom

A

multiple

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17
Q

Bond Orders for Single, Double and Triple bonds

A

Single: 1
Double: 2
Triple: 3

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18
Q

Property of Covalent: Bond Length

A

average distance between two nuceli in a bond

as number of shared electron pairs INCREASES, bond length DECREASES

Triple < Double < Single

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19
Q

Property of Covalent: Bond Energy

A

energy required to break a bond and separate compounds in gaseous atomic states

greater the shared pairs, the more energy required to break bonds and the stronger the bond!

Triple > Double > Single

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20
Q

Property of Covalent: Polarity

A

when two atoms have a relative difference in electronegativities

atom with the higher electronegativity hogs the electrons more

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21
Q

Dipole

A

a polar bond, positive end has less electronegative atom and negative end has the more electronegative atom

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22
Q

Non Polar Covalent Bond

A

equal distribution of electrons with identical/near identical electronegativity atoms

Diatomic atoms, bonds between atoms with a deltaElectronegativity less than 0.5

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23
Q

Polar Covalent Bond

A

atoms with different electronegativities (0.5-1.7 so it doesnt form ionic bond)

24
Q

Dipole Moment

A

occurs for polar covalent bonds

vector point towards partial negative

p =q * d

p = dipole moment 
q = magnitude of charge
d = displacement vector
25
Debye Units
columbs - meters ; measurement of dipole moment
26
Coordinate covalent bonds
shared electrons originate from same atom one lone pair attacks another atom with unhybridized p-orbital typically bound in lewis acid/base reactions
27
Lewis Acid
compound which accepts lone pair of electrons
28
Lewis Base
compound which donates lone pair of electrons
29
Bonding vs Non Bonding Electrons
B: electrons involved in the covalent bond in Valence shell NB: electrons in Valence shell not involved in covalent bond
30
Lone Pairs
electron pairs in valence shell that are associated with only one nucleus and not shared or bonded
31
Most stable arrangement is one that...
minimizes the number and magnitude of formal charges
32
Steps of Drawing Lewis Structure
1) Draw arrangement of elements, least electronegative atom in center 2) Count all valence electrons of the atoms and sum them together 3) Draw single bonds between atoms, each constitutes 2 valence electrons 4) Complete octets of all atoms by adding VE pairs 5) place extra electrons on central atom 6) if octet of central is not filled, create double.tripple bonds using said lone pairs
33
Terminal Positions of Lewis Structure
H, F, Cl, BR, I
34
Formal Charge =
V - N nonbinding - N bonding N nonbonding = number of nonbonding electrons N bonding = number of bonds V - normal number of electrons in the atoms valence shell usually
35
Resonance structures/Resonance Hybrid
all possible lewis structures of a molecule ; actual structure is a hybrid of all structures known as resonance hybrid
36
Stability of Resonance Structures
1) lewis structure with small or no formal charge is most stable 2) lewis structure with less separation between opposite charges is prefered 3) lewis structure in which negative formal charhes are placed on electronegative atoms is more stable
37
Lewis Structures: Exception to Octet rule
remember all after period 3 and H, He, Li, Br, B can have more or less thant four bonds and electrons on central atom! extra electrons go to d subshell
38
VSEPR Theory
three dimensional arrangement of atoms surrounding central atom is determined due to repulsions between bonding and non-bonding electrons to orient them as far as possible to minimize repulsive forces
39
Predicting Geometrical Structure
1) Draw Lewis Structure 2) Total number of bonding and nonbonding electron pairs in the Valence shell of central atom 3) orient so electron pairs are as far as possible
40
Linear
180 degrees, 2 Electron density areas
41
Trigonal Planar
120 degrees, 3 electron density areas
42
Tetrahedral
109.5 , 4 electron density areas
43
Trigonal Bipyramidal
90, 120, 180 , 5 electron density areas
44
Octahedral
90, 180, 6 electron density areas
45
Electronic vs Molecular Geometry
E: spatial arrangement of all pairs of electrons around the central atom (bonding and non bonding) M: spatial arrangement of only bonding pairs of electrons ; which MCAT focuses on
46
Ideal Bond Angle
angle between bonds nonbonding pairs exert more repulsion than bonding pairs as they are closer to the nucleus
47
A compound with polar bonds may be polar or nonpolar depending on __
spatial orientation of the polar bonds in the molecule ; if dipole moments cancel each other out (vector sum = 0) then a nonpolar compound is made
48
Molecular Orbital
when two atoms bond to form a compound, the atomic orbitals interact
49
Bonding vs Antibonding Orbitals
B: sign of both atomic orbitals are the same AB: sign of atomic orbitals are different
50
Sigma Bond
orbitals overlapping head to head free rotation about axes
51
Pi Bond
orbitals overlap so two parallel electron clouds are formed no free rotation due to electron densities are parallel
52
Intermolecular Forces
impact physical properties like melting and boiling point 1) Van der Waals 2) Dipole - Dipole 3) Hydrogen
53
van der Waals
unequal distribution of electron density causing rapid polarization/counterpolarization forming negative and positive portions on molecules leading to temporary attraction between neighboring molecules weakest force, large moleucles are more easily polarizable
54
Dipole-Dipole
polar molecules orient themselves so oppositely charged ends are lose to one another attractive electrostatic forces present in solid and liquid phases but not gases due to distance of particles higher mp and bp
55
Hydrogen bonds
strong form of dipole dipole that may be intra or inter moelcular H bonded to an highly electronegative atom (O, N, F), it carries a positive charge to interact with partial negative charges of nearby electronegative atoms very high boiling points due to high energy required to break H bonds