Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

CHEM1602 > Section A 1 > Flashcards

Section A 1 Flashcards

1
Q

So we define a mole (mol) of a substance as containing …. molecules.
This value is …

A

6.022 x 10^23

Avogadros number, NA (or sometimes L)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

M(Mg) = 24.31 x 1 g mol-1 = 24.31 g mol-1

This value is called the….. and it … units, in contrast to the relative ….., which ….

A

molar mass, M
has

molar (atomic) mass, Mr
is unitless

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Using ….. the mass of the individual isotopes can be determined.

A

a mass spectrometer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Relative atomic mass is used to calculate ….

And the molar mass of a substance, M, is obtained by …..

A

relative molecular mass, Mr:

e.g. Mr(H2O) = (1.008 x 2) + (15.999 x 1) = 18.015

multiplying Mr by 1 g mol-1

e.g. M (H2O) = 18.015 x 1 g mol-1 = 18.015 g mol-1

This means that if we want to use 1 mol of water in the laboratory we would need 18.015 g.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

No of mols (mol) =

A

mass (g) / molar mass (g mol-1)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

An implication of describing the electron as a wave is the uncertainty principle –

A

its position and momentum (energy) cannot not simultaneously be determined.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Each electron in an atom is labelled with four quantum numbers. The first is….

It tells you about ….

A

the Principal quantum number:
n (the shell):
n = 1, 2, 3, …

how big the orbital is, or how far (on average) an electron
occupying it is from the nucleus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

The second quantum number is ….. :

This tells you about….:

A

the angular momentum quantum number: l
l = 0, … n-1

the shape of the orbital

l = 0 is an s orbital,
l = 1 is a p orbital,
l = 2 is a d orbital, etc.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

The third quantum number is …. :

These are … orbitals, and tell you about ….

A

the magnetic quantum number: ml :

ml = -l, … +l
e.g. if l = 1, ml = -1, 0, +1.

the px, py, and pz

the orientation of the orbital

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Wavefunctions can be used to calculate the radial distribution function of the orbital i.e. …

A

how the probability of finding the electron varies with distance from the nucleus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

The position where the function equals zero is called a ….and there is zero probability of the electron being found there.

A

node

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

the Pauli exclusion principle -

A

A maximum of two electrons can share each orbital, with the same values of n, l, ml but different spin (ms = +1/2 and -1/2).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Hunds Rule of maximum multiplicity -

A

If two or more orbitals have the same energy, then electrons will spread out to occupy the maximum possible number of these, maximising the number of parallel spins.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

If the electrons occupy separate orbitals then they occupy different regions of space so there is …. electrostatic repulsion. This is a … energy arrangement.

A

less

lower

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Why is cobalt essential for vitamin B12 function?

A

Vitamin B12 has an unusual Co-C bond which
can be broken three ways:
1. To form Co(III) and CH3-
(anion)

  1. To form Co(II) and CH3.
    (rodnik)
  2. To form Co(I) and CH3+
    (kation)

Essential to its function that Co is stable in three oxidation states and they are relatively close in energy to allow fast conversion between them.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Przypomnienie:

Compounds which require more than an octet of electrons in order to draw a Lewis structure are called …..

A

Ans. hypervalent compounds.

Although period 2 elements obey the octet rule very well,

Period 3 elements begin to show some deviations.
e.g. PCl5 can only be explained if P has 10 electrons in its outer shell
In SF6 S must have 12 electrons in its outer shell

17
Q

Znając: Number of electron pairs around central atom: 2

Podaj:

Shape:
Bond Angles:
Example:

A

Linear
180
BeF2

18
Q

Znając: Number of electron pairs around central atom: 3

Podaj:

Shape:
Bond Angles:
Example:

A

Trigonal planar
120
BF3

19
Q

Znając: Number of electron pairs around central atom: 4

Podaj:

Shape:
Bond Angles:
Example:

A

Tetrahedral
109.5
CF4

20
Q

Znając: Number of electron pairs around central atom: 5

Podaj:

Shape:
Bond Angles:
Example:

A

Trigonal bipyramidal
90, 120
PF5

21
Q

Znając: Number of electron pairs around central atom: 6

Podaj:

Shape:
Bond Angles:
Example:

A

Octahedral
90
SF6

22
Q

Znając: Number of electron pairs around central atom: 7

Podaj:

Shape:
Bond Angles:
Example:

A

Pentagonal bipyramidal
90, 72
IF7

23
Q

Structures based on tetrahedral geometry:

  1. No lone pairs
  2. One lone pair
  3. Two lone pairs
A
  1. Tetrahedral
  2. Trigonal pyramidal
  3. Bent
24
Q

Structures based on trigonal bipyramidal geometry

  1. No lone pairs
  2. One lone pair
  3. Two lone pairs
A
  1. Trigonal bipyramidal
  2. Disphenoidal
  3. T-shaped
25
Q

Structures based on octahedral geometry

  1. No lone pairs
  2. One lone pair
  3. Two lone pairs
A
  1. Octahedral
  2. Square pyramidal
  3. Square planar
26
Q

Bond angles:

H20
NH3
CH4

HCN
CO2
Acetone

SF4

A

H2O:
e = 104.5 ‘bent’

NH3:
e = 107.3 ‘trigonal pyramidal’

CH4:
e = 109.5 ‘tetrahedral’

bond angle gets smaller due to lone pair repulsion (od dołu do góry)

HCN:
e = 180 ‘linear’

CO2:
e = 180 ‘linear’

Acetone
‘Trigonal planar’

SF4:
The F-S-F angle involving the axial F atoms is 173

27
Q

Limitations of the Lewis model of bonding

A

It also does not explain some other observations, for example that the oxygen molecule is paramagnetic (it has unpaired electrons), which is not predicted by the Lewis model.

28
Q

ATP is made up from three sections:

A

A purine base – Adenine
A pentose sugar – Ribose
A phosphate section - Triphosphate

Adenine + Ribose = Adenosine

29
Q

These bonds are called pi or π-bonds. They have two …., above and below the line between the atoms.

A

lobes

30
Q

Combinations of waves can either be constructive or destructive.
We use this argument when combining the s orbitals to from a bond:

If they combine constructively then electron density between the atoms is …… This is called ….
If the s orbitals combine destructively then electron density between the atoms is and this is called ….

A

increased
a bonding molecular orbital.

decreased
an anti-bonding molecular orbital.

31
Q

Bond Order =

A

[(number of bonding electrons) – (number of anti-bonding electrons) ] /2

32
Q

Bond order of:
1. He2

  1. H2
  2. He2 +
A
  1. So for He2: Bond Order = (2 – 2) / 2 = 0
    A bond order of zero means there is no bond, so the He2 molecule does not exist.
  2. H2 = (2 – 0) / 2 = 1
    A bond order of 1 is equivalent to a single bond using the Lewis model, and is consistent with observations.
  3. He2 + = (2 – 1) / 2 = ½
    A bond order of ½ is something that is not encountered in
    the Lewis electron pair model, but something that MO
    theory can predict with ease.

What this means is that a bond of about half the strength
of a single bond can form between the He atoms of He2+

This means that this molecule can exist, but will not be
very stable. Its existence is likely to be transient.

33
Q

Rozwiń skróty:
LUMO
HOMO

A

Lowest unoccupied MO (Molecular Orbital)

Highest occupied MO

CHEM1602 (7 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions