Chapter 3 Flashcards

1
Q

exceptions to the octet rule

A

hydrogen, lithium-2

berrylium-4

boron- 6

period three and greater can have expanded octet

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2
Q

what elements always follow the octet rule

A

C, N, Na, F, Mg

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3
Q

ionic bond

A

transfer electrons from atom with low IE (metal) to high IE (non metal)

held by electrostatics and form lattice to maximize force

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4
Q

When are ionic bonds used

A

Difference of EN is greater than 1.7

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5
Q

Characteristics of ionic bond

A

strong, high BP/MP, dissolve in polar, good conductors

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6
Q

covalent bond

A

electron pair shared between atoms (non metals with similar EN)

electrons attract to positive nuclei

can be equal or unequal

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7
Q

Covalent bond characteristics

A

lower mp/bp

weaker

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8
Q

bond order

A

number of shared electron pairs between 2 atoms

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9
Q

bond length

A

distance between 2 nuclei

more bonds= increase electrostatic pull, decrease length

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10
Q

bond energy

A

energy required to break a bond

greater number of shared electrons means higher energy and stronger

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11
Q

polarity

A

differ in EN, differ in sharing

higher EN gets more electron density

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12
Q

non polar covalent

A

nearly identical EN share electrons and have equal distribution (no separation of charge)

EN difference is less than .5

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13
Q

polar covalent

A

share electrons unevenly, has separation of charge

EN difference between .5 and 1.7

EN atom has more electrons, partial negative

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14
Q

dipole moment

A

vector quantity

p=qd

q= charge, d= displacement

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15
Q

coordinate covalent bond

A

both of shared electrons are contributed by one of the atoms

lonepair attacks unhybridized p orbital

lewis acid and base

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16
Q

bonding electrons

A

electrons involved in covalent bond

17
Q

formal charge

A

difference between number of valence electrons in lewis and number of valence in neutral atom

assumes equal sharing, underestimates EN

18
Q

lewis structure

A

most stable form will minimize number and magnitude of formal charge

19
Q

formal charge calculation

A

number of valence electrons in atom

sum to make total

FC= Valence- nonbonding -1/2 bonding

20
Q

most stable lewis

A

contributes more to resonance

prefer small or no formal charge

prefer less separation between opposite charge

prefer negative on EN

21
Q

VSEPR

A

uses lewis structure to predict molecular geometry

3D determined by repulsions

22
Q

electron geometry

A

spatial arrangement of all electron pairs around center

bonding and lp

23
Q

molecular geometry

A

spatial arrangement of only bonding pairs of electrons

24
Q

coordination number

A

number of atoms that are surrounded and bonded to a central atom

25
Q

molecular orbital

A

probability of finding the bonding electron in a given space formed when atomic orbitals interact into a compound

26
Q

bonding vs. antibonding MO

A

bonding: same sign atomic orbitals

nonbonding is different signs

27
Q

pi bond

A

overlap to have 2 parallel electron cloud densities

no rotation, parallel

28
Q

sigma bond

A

head to head overlap, can rotate freely due to single and linear nature

29
Q

intermolecular forces

A

keep substance together, electrostatic interactions

dispersion < dipole < hydrogen

30
Q

Dispersion/ Van Der Walls

A

temporary dipoles causing interactions due to random unequal electron distribution

negative causes attraction to other positive when proximal

occurs more in larger molecules

31
Q

dipole- dipole

A

opposite ends of polar molecules attract with other dipoles

Not in gas (too far)

in polar, increases MP/BP

32
Q

hydrogen bonds

A

strong dipole

can be intra or intermolecular

hydrogen with EN atom will act as a proton and interacts with negative nearby such as F,O,N

increases BP