Term Test 1 Vocab Flashcards Preview

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Flashcards in Term Test 1 Vocab Deck (56)
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1

covalent bond

two electrons shared between 2 nuclei (localized covalent bond)

2

Trigonal Planar

flat molecule, has pi bond/sp2 orbitals, bond angle of 120°

3

Tetrahedral

pyramid shaped, sp3 hybridized, 4 substituents or 3 and a lone pair, bond angle is 109.5°

4

sp3 orbitals

3 p orbitals blended with 1 s, cannot form a pi bond as all p orbitals are already used in sigma bond

5

sigma bond

localized electrons, overlap of sp3 orbital and p orbital

6

Which orbital is involved in pi bond

p orbital excluded from sp2 hybridization will be involved in pi bonding

7

pi bond

delocalized, easily broken

8

linear molecule

sp orbitals, two pi bonds formed from the two p orbitals not involved in hybridization, bond angle of 180°

9

Is a double bond twice as strong as a single bond?

No, because pi bond is weaker than sigma bond and a double bond is composed of a pi and sigma bond.

10

Difference between polar and polarizable

Polar is when one atom in a molecule carries a negative charge more than the other one (ex. H - Cl, chlorine is more negative). Polarizable is the response of the bond to a dynamic system, electrons of larger molecules are further from nucleus and can be pulled away more easily.

11

The larger the atom...

...the more likely the bond can be polarized. A temporary dipole movement can be formed just by electron fluctuations around the atom.

12

Electronegativity increases and decreases in which way on periodic table?

Decreases as you go down a period, and increases as you go across the period.

13

Give examples of groups that donate electrons

Electron donating groups have low electronegativity and include: CH3, CH2CH3, Li, Mg, Al (metals)

14

dipole moment

measurable property that describes a separation of charge in the molecule, vector sum of all bond dipoles

15

Electron numbers of common elements

1 - H, Li
4 - C
5 - N, P
6 - O, S
7 - Cl, Br, F

16

Formal charges

electron bookkeeping, sum of all formal charges must equal overall charge of the molecule.

17

formal charges can give you info about?

p orbitals

18

making bonds...

releases energy (this is why atoms bond because they are more stable bonded than separate)

19

breaking bonds...

absorbs energy

20

Aufban

lowest energy orbitals fill first. 1s, 2s, 2p, 3s, 3p, 4s, 3d

21

pauli exclusion

electrons have up spin and downspin only 2 e- can occupy an orbital and must have opposite spin

22

Hund's rule

If two or more empty orbitals of equal energy are available, one electron occupies each with parallel spins until all orbitals are half full.

23

Why are sp3 bonds strong?

the orbitals are oriented strongly in a certain direction so it allows for better overlap of orbitals in a bond.

24

Bond character of CH4 molecule

each C-H bond has strength of 439 kJ/mol and bond angle of 109.5°, length of 109 pm.

25

Resonance Structures

- do not change geometry of molecule in ANY WAY
- forms only differ in their placement of pi bond electrons and lone pairs
- one alone is wrong, molecule is blend of all of them, though some are upweighted

26

Resonance Rules (in order of most importance)

1. Number of pi bonds - delocalization of electrons stabilizes the molecule so form with most pi bonds makes greatest contribution to its stability (don't move pi bonds from benzene ring, it will decrease stability)

2. formal charges - fewer formal charges are more important. If forms have equal numbers of formal charges then the form that has the most EN atoms carrying neg charge and least EN atoms carrying pos charge is better

3. Inductive effects - electron donating groups (alkyls) help to stabilize positive charge (give electrons to positive site), electron withdrawing groups (halogens, O, N) pull electrons and thus stabilize negative charge.

27

Why is the terminal carbon on allene twisted? (C3H4)

middle carbon is sp hybridized, is bonding with two carbon substituents which are sp2 hybridized. The two empty orbitals on the middle carbon are not on the same plane and thus the pi bonds formed are at different angles.

28

Similarities in structure imply...

similarities in properties and behaviour

29

Amide

NH

30

Amine

NH2