MCAT > Chemistry Chapter 3 > Flashcards

Chemistry Chapter 3 Flashcards

(54 cards)

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1
Q

What are the 3 exceptions to the octet rule

A
  1. Incomplete octet: more stable with less than 8 electrons in valence shell
  2. Expanded octet: Can hold more than 8 electrons in their valence shell

3, odd number of electrons : any molecule that has odd can’t even distribute the electrons to give 8 to each atom

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2
Q

What elements are incomplete octet exceptions

A

Hydrogen
Helium
Lithium
Beryllium
Boron

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3
Q

Which ones are exceptions for expanded octet

A

Phosphorus
Sulphur
Chlorine etc

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4
Q

Ionic bonding mean

What type of structures are created instead of individual molecular bonds

A

Metal and non metal bonding , opposite charges

Latttice structures
Rows of cations and anions

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5
Q

What is covalent bonding

A

Like for example diatomic fluorine

Bonding between 2 non-metals

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6
Q

2 types of covalent bonding

If electron pair is shared equally are they polar or not polar
If electron pair is not shared equally the bond is polar or non polar

A

EQUALLY - NONPOLAR

NOT EQUALLY - POLAR

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7
Q

If shared electrons are contributed by only one of the two atoms, the bond is called

A

Coordinate covalent

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8
Q

Metals lose electrons to become
Non metals gain electrons to become

A

Metal cation

Nonmetal anion

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9
Q

Are electrons shared in an ionic bond

A

No

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10
Q

Why do metals have ionic bonds with nonmetals

A

Metals have low ionization energies and nonmetals have high electron affinities so they attract each other

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11
Q

Ionic compounds characteristics

A

High boiling point
High melting point
Don’t share electrons
Good conductors of heat and electricity
Solubility in water

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12
Q

Why is it that they share electrons in covalent bonds

A

Because it is more energy efficient to share than to create ions

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13
Q

What does bond order mean

A

How number shared electrons pairs there are between 2 atoms

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14
Q

If shared electrons pairs increase, the 2 atoms are pulled closer or further together, and then what happens to bond length

A

Closer together
Decrease in bond length

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15
Q

Is triple bond or single bond shorter

A

Triple cuz closer together

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16
Q

Is bond strength better for triple bond or single bond

A

Triple

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17
Q

What is bond energy

A

Energy required to break a bond by separated compounds into their isolated states

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18
Q

Do triple bonds or singular bonds have more bond energy

A

Triple more because its strong adn thus need more energy to break apart

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19
Q

What is polarity in terms of electronegativity

A

Two atoms have a relative difference in electronegativity

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20
Q

How do we know which atom gets a larger share of electron density during violent bonds

A

The one with higher electronegativity

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21
Q

Polar bonds have a dipole

Is the positive r or negative end more electronegative

A

Negative end is more electronegative

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22
Q

Naturally occurring diatomic elements name and ho many are there

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A

H2
N2
O2
F2
Co2
Br2
I1

7

23
Q

If only moderate difference in electronegativity, will they share electrons evenly? Is it polar or nonpolar

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A

Unevenly
Polar

24
Q

High electronegativity is polar or non polar

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A

Polar is higher

Nonpolar < Ionic < Polar

25
When you put an arrow between HCl to show electronegativity, which side is the end and which side points
Points is towards chlorine side because it’s negative side. End of arrow has a positive for hydrogen because of partial charge
26
P= qd equation explain for dipole moment
P is dipole moment Q is charge magnitude D is displacement separating 2 partial charges distance
27
Does Lewis acid or based donate electrons
Lewis acid - accpet Lewis base - donate
28
Least or most electronegative atom is always centre of Lewis diagram
Least
29
How can formal charge be calculated
Formal charge = valence electrons - dots- sticks Formal charge : valence electrons - nonbonding electrons - 1/2 ( bonding electrons)
30
Difference between FC and oxidation number
Formal charge is electronegativity difference Oxidation number overestimates this value
31
Resonance structures meaning How can they be shown
Different placement of electrons for the same 2 atoms bonding Double headed arrow between them
32
Are Lewis structures with no formal charge preferred
Yes
33
BeCl2 is what shape
Linear
34
What is BH3 shape
Trigonal planar
35
What is CH4 shape
Tetrahedral
36
PCl5 shape
Trigonal pyramidal
37
SF6 is what shape
Octahedral
38
How many degrees is linear Trigonal planar Tetrahedral Trigonal pyramidal Octahedral
180 120 109.5 90,120,180 90,180
39
All 2 atom molecules shapes are
Linear
40
Given a 3 atom molecules , what are the two shapes possible and how you know
Linear and bent The only way you know is if there is no lone pair on central atom its linear, if there is, its bent
41
Why is NH3 a Trigonal pyramidal and not tetradral
That’s because there’s 4 things attached to it, including the lone pair
42
For 4 atom molecules , how do you know if it is Trigonal planar or Trigonal pyramidal
If there is no lone pair on central atom, then it is Trigonal planar If there is lone pair on central atom, then it is Trigonal planar
43
5 atom molecules can only be what shape
Tetrahedral
44
How do i know their difference between electronic geometry and molecular shapes
Electron geometry is counting how many bonds and lone pair things are attached to the middle atom Molecular geometry is done through counting how many thigns are in the atom combination, adn then checking if they have lone pairs for the electrons to repel
45
Do you use electron or molecular to find ideal bond angle
Using geometric geometry
46
For what difference in EN will a nonpolar covalent, polar covalent and ionic bond form
0-0.5 0.5-1.7 1.7 or higher
47
What is the weakest intermolecular force, medium and highest
London forces Dipole dipole Hydrogen bond
48
London dispersion happens in all molecules but especially which ones
Nonpolar molecules
49
Which molecules have dipole dipole forces
Polar molecules
50
Another name for London dispersion forces
Van der Waals force
51
The only intermolecular force between noble gases are
London force
52
Hydrogen bonds exist in molecules that contain a hydrogen bonded to which 3 atoms
Fluorine oxygen nitrogen
53
Benefits of hydrogen bonding
It is intra and intermolecular bond Stronger form of dipole dipole High boiling points
54
What happens in dipole dipole interaction
Dipole consists of a side with partial positive and partial negative regions. The positive end of one molecule is attracted to the negative end of hte other molecule
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