Topic 1: Atomic Structure & The Periodic Table Flashcards

1
Q

What is the definition of relative atomic mass ?

A

The weighted mean mass of an atom of an element relative to the 1/12th the mass of a carbon-12 atom

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2
Q

What are isotopes

A

Atoms of the same element with the same number of protons but a different number of neutrons

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3
Q

What has to be done in order to calculate the relative atomic mass?

A

Chemical analysis (mass spectrometry) is carried out.
Gives us info on the relative abundance of each isotope in the sample

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4
Q

Molecular mass of CO2

A

12.0 + (16.0 x 2) = 44.0

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5
Q

What does a mass spectrometer measure

A

The masses of atoms and molecules (as well as the fragments that make the molecule up)

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6
Q

On a mass spectrometry graph how do we calculate relative atomic mass when y axis is %

A

(Mass x abundance)+(mass x abundance)
———————————————————-
100

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7
Q

On a mass spectrometry graph how do we calculate relative atomic mass when y axis is relative abundance instead of percentage abundance?

A

(Mass x abundance) + (mass x abundance)
—————————————————————
Sum of isotopic abundances (peaks on graph)

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8
Q

what does the molecular ion peak (peak furthest to the right) tell us ?

A

Relative molecular mass

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9
Q

What are the 4 stages of mass spectrometry

A

Ionisation
Acceleration
Deflection
Detection

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10
Q

Why must the ionisation chamber in mass spectrometry be a vacuum?

A

If there were any loose gas particles they would be ionised and picked up on the detector which would interfere with results

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11
Q

What is important about the sample in mass spectrometry

A

The sample must be vaporised so that all particles are in a GASEOUS state

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12
Q

Describe how ionisation works in a mass spectrometer

A

Sample is inserted and bombarded with a beam of high energy electrons.
Electrons are knocked off- creates positive ions

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13
Q

Why must the sample be ionised (mass spectrometry)

A

Must be positive ions in order to get detected

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14
Q

How are the ions accelerated (mass spectrometry)

A

Electric field helps accelerate the ions

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15
Q

What helps deflection (mass spectrometry)

A

Magnetic field created by an electromagnet - bends the path of ions

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16
Q

What can you find out from position of detection? (Mass spectrometry)

A

The larger the mass of the ions, the less they are deflected and the position of detection depends on amount of deflection

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17
Q

What is the order of how shells are filled

A

1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 4d, 4f

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18
Q

What do the coefficient, the letter and the power represent eg. 3s^2

A

3 - quantum shell
s- type of orbital
2- number of electrons

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19
Q

What is the maximum amount of electrons an s-orbital can hold

A

2

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20
Q

What is the maximum amount of electrons a p-orbital can hold?

A

6

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21
Q

What is the maximum amount of electrons a d-orbital can hold?

A

10

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22
Q

What is the maximum amount of electrons an f-orbital can hold?

A

14

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23
Q

What is the shape of an s-orbital

A

Spherical

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24
Q

What is the shape of a p-orbital

A

Figure of 8
Aligned along perpendicular axes

25
Q

How many types of d orbital are there

A

5

26
Q

Why does the 4s orbital fill before the 3d orbital

A

The energy level of 4s is slightly lower than 3d

27
Q

What makes copper an exception to the rule of shell filling ?

A

3d orbital fills fully before the 4s orbital

28
Q

What makes chromium an exception to the rule of shell filling ?

A

The orbitals 3d and 4s are only half-filled

29
Q

What do we need to remember when emptying the orbitals ?

A

Although in most cases (bar 2 exceptions) 4s fills before 3d, when emptying the 4s empties before the 3d orbital

30
Q

What is Hunds rule of electrons in boxes ?

A

States that electrons will occupy the orbitals singularly before pairing takes place

31
Q

What is the Pauli Exclusion Principle ?

A

States that 2 electrons cannot occupy the same orbital unless they have opposite spins.

32
Q

How is the direction of electron spin shown?

A

Upwards and downwards arrows

33
Q

How can you tell which block an element is in from looking at their electronic configuration?

A

Example : If it ends in 3d then it is in d-block
If it ends in 4s it is in s-block

34
Q

Define 1st Ionisation energy

A

The energy required to remove 1 electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions

35
Q

How is atomic radius a factor in removing electrons ?

A

The more shells an atom has, and therefore the further away the outer electrons are from the nucleus, the less attraction they experience (easier to remove electrons)

36
Q

How is nuclear charge a factor in removing electrons ?

A

The more protons, the greater nuclear charge, the greater the attraction felt by the outer electrons (harder to remove)

37
Q

How is electron shielding a factor in removing electrons ?

A

As the number of electrons between outer electrons and nucleus increases, the outer electrons feel less attraction towards the nuclear charge (easier to remove)

38
Q

What is the general trend in ionisation energies down a group

A

Generally decrease

39
Q

What is the general trend in ionisation energies across a period

A

Ionisation energy generally increases due to increased nuclear charge and the fact that the electrons being removed are from the same sub-shell and therefore have similar shielding.
Drops slightly between groups 2&3 and 5&6

40
Q

Explain the drop in ionisation energy between groups 2 & 3

A

In a group 3 element, the highest energy (outer) electron occupying a 3p rather than a 3s orbital.
3p has a slightly higher energy so it is slightly further away from the nucleus. It also experiences additional shielding from the 3s orbital.
Both factors override the effect of an extra proton (increased nuclear charge) and result in a drop of ionisation energy

41
Q

Explain the drop in ionisation energy between groups 5 & 6

A

The electrons being removed from both group 5 & 6 elements are from p-orbitals.
However, the electron being removed from the group 6 element comes from a paired orbital whereas the electron being removed from a group 5 element comes from a singly paired orbital.
The extra repulsion between paired electrons in the group 6 element makes it easier to remove the one electron ( less energy is needed)

42
Q

What is the successive ionisation energy

A

Measure if the energy required to remove each electron in turn

43
Q

Why is each successive ionisation energy greater than the last?

A

As each electron is removed the ion becomes increasing positive
As each electron is removed there is less repulsion between the electrons and each shell will be drawn slightly closer to the nucleus
As the distance of each electron from the nucleus decreases slightly the nuclear attraction increases.

44
Q

What do large jumps on a successive ionisation energy graph represent

A

A change in shell

45
Q

What do dots on a successive energy graph represent

A

Electrons

46
Q

How can you work out the group number from looking at a graph showing successive ionisation energies

A

The number of electrons before the first big jump

47
Q

What does the group number tell us

A

The number of electrons in the outer shell

48
Q

What does the period tell us about the element

A

The total number of shells

49
Q

Where are s-block elements located on the periodic table

A

Groups 1 & 2 and helium

50
Q

Where are the p block elements located on the periodic table

A

Right hand side bar helium

51
Q

Where are the d-block elements located on the periodic table

A

Transition metal area (centre)

52
Q

As you go across the metals (Li, Be, Na, Mg, Al) explain how the melting and boiling points are affected

A

Melting and boiling points increase as metallic bonds get stronger due to…
More delocalised electrons per metal cation and atomic radius decreases

53
Q

Explain why the melting and boiling points peak (C, Si)

A

Macromolecules (giant covalent ) have very strong covalent bonds

54
Q

Explain why melting and boiling points decrease (N,O,F,P,S,Cl)

A

These elements are simple molecular structures and have weak London forces which are easily overcome

55
Q

Explain why the noble gases have the lowest melting and boiling points

A

They are monoatomic elements - have very weak London forces between the atoms

56
Q

Explain the term orbital

A

Sub shells were an electron is likely to be found

57
Q

What is periodicity

A

The trends in properties of elements as you go across the periods of the periodic table

58
Q

What happens to I.E at the start of a new period

A

Falls dramatically

59
Q

Define relative isotopic mass

A

The mass of an atom of an isotope relative to 1/12th the mass of a carbon-12 atom