3.1.1 Atomic Structure

Question 1

What is meant by atomic number?

Answer 1

Number of protons (in non-ions electrons too)

Question 2

What does isotopes mean?

Answer 2

Atoms of the same element with different mass numbers due to different number of neutrons

Question 3

What is the a level definition for Relative Atomic Mass?

Answer 3

The average mass of an atom of an element relative to 1/12th the mass of an atom of carbon-12

Question 4

What is the a level definition for Relative Isotopic Mass?

Answer 4

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

Question 5

What is the calculation for RAM?

Answer 5

((mass x abundance)+(mass x abundance))/100

Question 6

What is mass spectrometry?

Answer 6

An analytical technique that measures the mass to charge ratio of different ions, it can be used to map the abundance of diff isotopes and calculate RAM

Question 7

3.1.1.3 Electrons occupy…

Answer 7

Energy Levels

Question 8

3.1.1.3 What is the relation between pqn/energy levels and the energy of electrons?

Answer 8

The higher the pqn/el, the more energy the electrons in it will have

Question 9

3.1.1.3 What does each energy level contain?

Answer 9

One or more sub-shells

Question 10

3.1.1.3 What are the names of the four major sub-shells, and how many electrons do they hold?

Answer 10

S (holds 2 due to having one orbital) P (holds 6 electrons due to three orbitals) D (has 10 electrons due to 5 orbitals) and F(unimportant, holds 14 electrons due to 7 orbitals)

Question 11

3.1.1.3 In what order are the sub-shells filled?

Answer 11

1s-2s-2p-3s-3p-4s-3d-4p-(5s-4d-5p-6s-4f)

Question 12

3.1.1.3 What is the elec config for Helium (2e-)

Answer 12

1s^2

Question 13

3.1.1.3 What is the elec config for Iron (26e-)

Answer 13

1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^6

(Ar)4s^2 3d^6

Question 14

3.1.1.3 What is the elec config for a Flouride ion/F- (10e-)

Answer 14

1s^2 2s^2 2p^6

(He)2s^2 2p^6

Question 15

3.1.1.3 What is each sub-shell made up of?

Answer 15

2 electrons

Question 16

3.1.1.3 How many orbitals does each sub-shell contain?

Answer 16

S sub shell- 1 orbital- 2 electrons
P sub shell- 3 orbitals- 6 electrons
D sub shell-5 orbitals- 10 electrons
F sub shell- 7 orbitals- 14 electrons

Question 17

3.1.1.3 How are electrons shown?

Answer 17

As arrows in box notation

Question 18

3.1.1.3 Why do electrons in the same orbital have opposite spin (like reversible reaction symbol)?

Answer 18

To minimize repulsion

Question 19

3.1.1.3 What are the four rules of electron configuration?

Answer 19

Aufbau Principle(enter lowest orbital available),
Hund’s Rule/Bus seat rule (electrons occupy orbitals singly before pairing up)
Pauli-Exclusion Principle (electrons in same orbital must have opposite spin)
Ion Formation (atoms lose electrons from highest occupied orbital excpet for TMs which lose 4s before 3d)

Question 20

3.1.1.3 What are the four rules of electron configuration?

Answer 20

Aufbau Principle(enter lowest orbital available),
Hund’s Rule/Bus seat rule (electrons occupy orbitals singly before pairing up)
Pauli-Exclusion Principle (electrons in same orbital must have opposite spin)
Ion Formation (atoms lose electrons from highest occupied orbital except for TMs which lose 4s before 3d)

Question 21

3.1.1.3 What two elements are the exception to the sub-shell order and why?

Answer 21

Copper and Chromium becuase an electron from the 4s orbital rises to fill the 3d sub shell as a completely full or half full d sub-level is more stable than a partially filled d sub-level- this is also true for the elements underneath copper like gold and silver, and Mo under chromium

Question 22

3.1.1.3 Isolectronic Meaning

Answer 22

Having the same number of electrons hence the same electron configuration

Question 23

3.1.1.3 What is different about the TM’s/d-block?

Answer 23

When the element becomes positive (e- removed) the electrons are first removed from the 4s orbital first (look at chemguide) but 3d is filled first.

Half-filled and fully filled subshell have got extra stability hence why Cu and Cr are different

Question 24

3.1.1.2 What is a TOF-MS used for?

Answer 24

To determine the relative masses/abundance of atoms and molecules. It measures this by timing how long it takes the different species to pass through a drift tube.

Question 25

3.1.1.2 What are the stages of TOF-MS?

Answer 25

Vaccum, Ionisation, Acceleration, Ion Drift, Detection and Data Analysis

Question 26

3.1.1.2 What happens during Vapourisation?

Answer 26

The sample is injected through a vaccum tube (so no other samples are analysed) and is vapourised(elec impact)

Question 27

3.1.1.2 What happens during Ionisation where the sample is vapourised?

Answer 27

Electron Impact- the sample vapourised and is bombarded with electrons from a hot cathode which knock an electron off the sample, giving it a positive charge but no change in mass. x=X+e-. Disadvantage- can cause fragmentisation ( when sample is broken down into smaller molecules) so is only used for elements/ small Mr compounds

Question 28

3.1.1.2 What happens during Ionisation where the sample is dissolved?

Answer 28

Electrospray Ionisation- sample dissolved in a volatile solvent (eg water or methanol) and injected through a
fine hypodermic needle to give a fine mist (aerosol). The tip of the needle is attached to the
positive terminal of a high-voltage power supply.
The particles are ionised by gaining a proton
(ie an H+ ion which is simply one proton) from the solvent as they leave the needle producing
XH+ ions (ions with a single positive charge and a mass of Mr + 1)

Simpler: high voltage is applied to sample so it gains an electron X(g) + H+= XH+(g)

Question 29

3.1.1.2 What happens during Acceleration?

Answer 29

The positive ions are accelerated using an electric field so they all have the same kinetic energy, to a -ve charged plate. All have same KE, so the velocity of each particle depends on its mass. Lighter particles velocity, and heavier particles have a slower velocity.

Question 30

3.1.1.2 What happens during Ion Drift?

Answer 30

The + ions travel through a hole in the -vely charged plate into a tube.TOF of each particle through this flight tube depends on its velocity which in turn depends on
its mass. All ions were released at the same time but due to their smaller mass, the lighter ions reach the detector first.

Question 31

3.1.1.2 What happens during Detection?

Answer 31

The+ ions hit a -ely charged electric plate, gain electrons. This generates a movement
of electrons and hence an electric current that is measured. The size of the current gives a
measure of the number of ions hitting the plate.

Question 32

3.1.1.2 What happens during Data Analysis?

Answer 32

Signal from the detector passed to a comp

which generates a mass spectrum. M/Z on the x axis, abundance on the y-axis

Question 33

.2 What is the equation for Mr of an isotope?

Answer 33

Isotopic mass/6.022x10^23

Answer in kg so multiple RIM by 10^-3

Question 34

What is the equation for KE and v?

Answer 34

KE=1/2mv^2

V= all root2KE/m

Question 35

.6 What is ionisation energy?

Answer 35

A measure of the energy required to completely remove an electron from an atom of an element- to form an ion

Question 36

.6 What is first ie?

Answer 36

The energy needed to remove 1 electron from each atom in 1 MOLE of GASEOUS atoms to form 1 mole of gaseous 1+ ions

Question 37

.6 The lower the ie

Answer 37

.6 The easier it is to form an ion

Question 38

.6 What is the equation for first ionisation energy?

Answer 38

X(g) arrow X+(g) + e-

Question 39

.6 What is the equation for the first ie of oxygen?

Answer 39

O(g) arrow O+(g) + e-

Question 40

.6 What are the factors affecting IE?

Answer 40

Nuclear charge – the larger the nuclear charge, more protons so more +vely charged nucleus, more attraction between it and outer electrons, the more difficult it is to remove an electron

Distance between nucleus and the electron – the further the electron is from the nucleus, less attraction between +ve nucleus and outer electrons, the easier it is to remove

Shielding – the more shells between the nucleus and outer electron, less attraction between +ve nucleus and outer electrons, the more easily the electron can be removed

Question 41

.6 Order Helium Fluorine and Neon from highest to lowest first ie and why

Answer 41

Helium-Neon-Fluorine
Helium highest first IE bc outer electron is closest to the nucleus and it has no inner shells of electrons for shielding.

Neon and fluorine have lower ionisation energies than helium due to the outer electron being further away from the nucleus and there being less shielding.

Fluorine has the lowest first ionisation energy. It has the same amount of shielding as neon but neon has a greater nuclear charge, meaning that the outer electron in fluorine is easier to remove.

Question 42

.6 What does SIE involve?

Answer 42

Successive ionisation energies involve removing additional electrons. Each electron that is removed has its own ionisation energy.

Question 43

.6 Describe SIE

Answer 43

The first electron needs the least energy to remove it because it is
being removed from a neutral atom. This is the first IE.
• The second electron needs more energy than the first because it is
being removed from a + 1 ion. This is the second IE.
• The third electron needs even more energy to remove it because it
is being removed from a +2 ion. This is the third IE.
• The fourth needs yet more, and so on.

Question 44

.6 Work out the electron configuration for the atom with following ies and its group
1st e- removed 496 2-4563 3-6913 4-9544 5-13352 6-16611 7-20115 8-25491 9-28934 10-141367 11-159079

Answer 44

• one electron furthest away from the positive nucleus (easy to remove)
  • eight electrons nearer in to the nucleus (harder to remove)
  • two electrons very dose to the nucleus (very difficult to remove because they are nearest to the positive charge of the nucleus).
  This tells you about the number of electrons in each main level ororbit: 2,8, 1

Group 1 as it has the biggest jump between 1 and 2

Question 45

Periodicity- Trend in first ie across period-

Answer 45

General increase along the period

Nuclear charge increases so electrons feel a stronger
electrostatic attraction towards the nucleus and are
harder to remove

Al lower than Mg due to e- being removed from sub-shell (3p) further from nucleus (increased shielding)

S lower than P due to pairing of electrons in 3p causing a repulsive force making an electron easier to remove.

Question 46

6. Trend in first ie down a group

Answer 46

IE decreases because
-Number of shells increases-
Shielding increases-
distance between positively charged nucleus and negatively charged outer electron increases so the electron is less attracted to the nucleus and requires less energy to be removed

Question 47

Why use P3 to identify trends?

Answer 47

• The first two periods are not typical. Period 1 contains only H and He. H is sometimes placed in a group on its own as it does not behave like any other element in Group 1. Helium is placed in group 0 due to its noble gas properties; however it has a s-block configuration!
• The second period (Li-Ne) contains the top elements of each group; they have very small sizes and relatively high ionisation energies, so again are atypical.
• Period 3 is better for studying periodic trends.

Question 48

Trends in AR across P3?

Answer 48

Decreases along the period

Nuclear charge increases as the number of protons increases

Similar shielding of electrons along the group due to all being in the same energy level

Atomic size decreases as electrons feel a stronger electrostatic attraction towards the nucleus

Question 49

Trends in EN across P3?

Answer 49

Nuclear charge increases so electrons feel a stronger
electrostatic attraction

Shielding is similar across p3 and not significant enough to overcome increasing nuclear
charge

Argon does not have an electronegativity value as it
does not form bonds

Question 50

Trends in EC across P3?

Answer 50

Na, Mg and Al are the only substances able to conduct electricity as they can form structures with free electrons

Al has the greatest number of delocalised electrons
So more are free to carry charge

Question 51

Trends in M/BP across P3

Answer 51

Na, Mg, Al strong metallic bonding with increasing electrostatic attraction between +ve ions and delocalised

Si- giant covalent structure with many strong covalent bonds

P, S, Cl-simple covalent structures with weak van der Waals forces

Ar-monatomic with weak van der Waals forces

P-In red phosphorus, each molecule exists in a tetrahedral structure. The atoms are joined by covalent bonds within the molecule. Melting point drops dramatically as intermolecular attractions are now due to weak van der Waals forces.

S-Molecule can exist in a eight membered ring structure. The atoms are joined by covalent bonds within the molecule. Melting point rises slightly as the molecule is bigger/heavier so has slightly stronger van der Waals’ forces.

Cl- exists a linear diatomic molecule. Melting point falls slightly as the molecule is smaller so has slightly lower van der Waals’ forces.

Ar-exists as a monatomic species and is lighter than Cl2 so VdW forces are weaker.