Atomic Structure Yr1

Question 1

What is the significance of a big jump between the 2nd and 3rd ionisation energies?

Answer 1

A big jump indicates that the element is in group 2 of the periodic table, as the 3rd electron is removed from an electron shell closer to the nucleus.

Question 2

What do the arrows in a spin diagram represent?

Answer 2

The arrows in a spin diagram represent the different spins of the electrons in an orbital.

Question 3

How do you fill up sub levels with several orbitals in the model of atomic structure?

Answer 3

When filling up sub levels with several orbitals, each orbital is filled singly before starting to pair up the electrons.

Question 4

Describe the structure of the periodic table.

Answer 4

The periodic table is split into blocks based on the type of subshell that the outer electron of an element is filling.

Question 5

What is an S block element?

Answer 5

An S block element is one whose outer electron is filling an s-subshell.

Question 6

Define a p block element.

Answer 6

A p block element is one whose outer electron is filling a p-subshell.

Question 7

How is a d block element defined?

Answer 7

A d block element is one whose outer electron is filling a d-subshell.

Question 8

Describe the electronic structure of O2-.

Answer 8

Oxygen (O) with the electronic structure 1s2 2s2 2p4 becomes O2- with the electronic structure 1s2 2s2 2p6.

Question 9

What is the electronic structure of Cu2+?

Answer 9

Copper (Cu) with the electronic structure 1s2 2s2 2p6 3s2 3p6 4s1 3d10 becomes Cu2+ with the electronic structure [Ar] 3d9.

Question 10

Do d-block elements lose their 4s electrons first when forming ions?

Answer 10

Yes, d-block elements lose their 4s electrons first when forming ions.

Question 11

Describe the electronic structure of Zn2+.

Answer 11

Zinc (Zn) with the electronic structure 1s2 2s2 2p6 3s2 3p6 4s2 3d10 becomes Zn2+ with the electronic structure [Ar] 3d10.

Question 12

Describe the first ionisation energy.

Answer 12

The enthalpy change when one mole of gaseous atoms forms one mole of gaseous ions with a single positive charge.

Question 13

Define the second ionisation energy.

Answer 13

The enthalpy change when one mole of gaseous ions with a single positive charge forms one mole of gaseous ions with a double positive charge.

Question 14

What are the three main factors that affect ionisation energy?

Answer 14

1. The attraction of the nucleus 2. The distance of the electrons from the nucleus 3. Shielding of the attraction of the nucleus

Question 15

Why are successive ionisation energies always larger?

Answer 15

The first electron removal forms a positive ion, increasing the attraction on the remaining electrons, requiring more energy to remove the next electron.

Question 16

How are ionisation energies linked to electronic structure?

Answer 16

Ionisation energies provide information about the electronic structure of an element. The closer an electron is to the nucleus and the less shielding it has, the higher the ionisation energy.

Question 17

Write the electronic structure of oxygen using letters and numbers.

Answer 17

The electronic structure of oxygen is 1s2 2s2 2p4.

Question 18

What is the equation for the first ionisation energy?

Answer 18

H(g) -> H+(g) + e-

Question 19

What is the equation for the second ionisation energy?

Answer 19

Ti+(g) -> Ti2+(g) + e-

Question 20

Describe the shape of the graph for periods two and three in the first ionisation energy of the elements.

Answer 20

The shape of the graph for periods two and three in the first ionisation energy of the elements is similar.

Question 21

Define periodicity.

Answer 21

Periodicity refers to a repeating pattern across a period.

Question 22

How does the first ionisation energy of helium compare to hydrogen?

Answer 22

Helium has a larger first ionisation energy than hydrogen because its first electron is in the first shell closest to the nucleus and has no shielding effects from inner shells. Additionally, helium has one more proton.

Question 23

Why do first ionisation energies decrease down a group?

Answer 23

First ionisation energies decrease down a group because the outer electrons are found in shells further from the nucleus and are more shielded, resulting in a smaller attraction of the nucleus.

Question 24

Why is there a general increase in first ionisation energy across a period?

Answer 24

There is a general increase in first ionisation energy across a period because the electrons are being added to the same shell, which has the same distance from the nucleus and same shielding effect. However, the number of protons increases, making the effective attraction of the nucleus greater.

Question 25

Why does sodium have a much lower first ionisation energy than neon?

Answer 25

Sodium has a much lower first ionisation energy than neon because its outer electron is in a 3s shell further from the nucleus and is more shielded.

Question 26

Why is there a small drop in first ionisation energy from magnesium to aluminum?

Answer 26

There is a small drop in first ionisation energy from magnesium to aluminum because aluminum is starting to fill a 3p subshell, whereas magnesium has its outer electrons in the 3s subshell. The electrons in the 3p subshell are slightly easier to remove due to their higher energy and slight shielding by the 3s electrons.

Question 27

Why is there a small drop in first ionisation energy from phosphorus to sulfur?

Answer 27

There is a small drop in first ionisation energy from phosphorus to sulfur because with sulfur, there are 4 electrons in the 3p subshell and the 4th electron is starting to doubly fill the first 3p orbital. When the second electron is added to a 3p orbital, there is a slight repulsion between the two negatively charged electrons, making the second electron easier to remove.

Question 28

Define second ionisation energy.

Answer 28

Second ionisation energy refers to the energy required to remove the second electron from an atom or ion.

Question 29

How does the second ionisation energy of lithium compare to helium?

Answer 29

The second ionisation energy of lithium is higher than that of helium because lithium has more protons and its second electron is removed from the 1s shell closest to the nucleus, experiencing less shielding from inner shells.

Question 30

Define isotopes.

Answer 30

Isotopes are atoms of the same element that have different numbers of neutrons and therefore different mass numbers.

Question 31

Define atomic number and mass number.

Answer 31

Atomic number (Z) is the number of protons in the nucleus, while mass number (A) is the total number of protons and neutrons in the atom.

Question 32

How can a mass spectrometer be used to identify elements and isotopes?

Answer 32

A mass spectrometer can determine the isotopes present in a sample of an element and identify elements by analyzing the mass-to-charge ratio of ions.

Question 33

Describe the process of electron impact ionization in a mass spectrometer.

Answer 33

Electron impact ionization involves firing high-energy electrons at a vaporized sample, causing outer electrons to be knocked out and forming positive ions with different charges.

Question 34

Explain the process of electrospray ionization in a mass spectrometer.

Answer 34

Electrospray ionization involves dissolving the sample in a volatile, polar solvent and injecting it through a fine needle. The sample gains a proton from the solvent, forming MH+ ions, which are then analyzed in the mass spectrometer.

Question 35

What is the purpose of maintaining a vacuum in a mass spectrometer?

Answer 35

A vacuum is necessary in a mass spectrometer to prevent air particles from ionizing and registering on the detector.

Question 36

List the essential steps in a mass spectrometer.

Answer 36

The essential steps in a mass spectrometer are ionization, acceleration, detection, and time measurement.

Question 37

Describe acceleration in a mass spectrometer.

Answer 37

Acceleration in a mass spectrometer refers to the process of increasing the velocity of positive ions using an electric field, while keeping their kinetic energy constant.

Question 38

What is the relationship between the velocity and mass of particles in a mass spectrometer?

Answer 38

In a mass spectrometer, lighter particles have a faster velocity, while heavier particles have a slower velocity.

Question 39

Define kinetic energy in the context of a mass spectrometer.

Answer 39

Kinetic energy in a mass spectrometer is the energy possessed by a particle due to its motion. It is calculated using the equation KE = 1/2 mv^2, where KE is the kinetic energy, m is the mass of the particle, and v is its velocity.

Question 40

How are positive ions distinguished in a mass spectrometer?

Answer 40

Positive ions in a mass spectrometer are distinguished by their flight times. The ions with smaller m/z values have the same kinetic energy as those with larger m/z values, but they move faster.

Question 41

Describe the detection process in a mass spectrometer.

Answer 41

In a mass spectrometer, the ions reach the detector and generate a small current. This current is produced by electrons transferring from the detector to the positive ions. The size of the current is proportional to the abundance of the species being analyzed.

Question 42

Describe the concept of relative atomic mass.

Answer 42

The relative atomic mass is a weighted average of all the isotopes of an element, as quoted on the periodic table.

Question 43

What is the formula to calculate the relative atomic mass (R.A.M) of an element?

Answer 43

R.A.M = (isotopic mass X % abundance) / 100

Question 44

How can you calculate the relative atomic mass using relative abundance data?

Answer 44

R.A.M = [(mass1 x abundance1) + (mass2 x abundance2) + ...]

Question 45

Describe the three sub-atomic particles and their positions in an atom.

Answer 45

Protons are located in the nucleus, neutrons are also located in the nucleus, and electrons are found in orbitals surrounding the nucleus.

Question 46

Describe how to calculate the percentage abundances of isotopes.

Answer 46

Percentage abundance can be calculated using the equation: R.A.M = (y x mass1) + [(1-y) x mass2], where y represents the percentage abundance of the first isotope and (1-y) represents the percentage abundance of the second isotope.

Question 47

Describe the composition of the mass spectra for Cl2 and Br2.

Answer 47

The mass spectra for Cl2 and Br2 show the relative abundance of different isotopes of chlorine and bromine in the diatomic molecules.

Question 48

How can mass spectrometers be used in planetary space probes?

Answer 48

Mass spectrometers in planetary space probes can identify elements on other planets by analyzing the composition of isotopes.

Question 49

Describe the process of measuring the molecular mass (M) of a molecule using a mass spectrometer.

Answer 49

When a molecule is put through a mass spectrometer with electron impact ionization, it often breaks up into fragments. The peak with the largest m/z corresponds to the complete molecule and is equal to the relative molecular mass (M) of the molecule.

Question 50

What is the relative abundance of the isotopes Cl³5 and Cl³7 in chlorine?

Answer 50

The relative abundance of Cl³5 is 75%, while the relative abundance of Cl³7 is 25% in chlorine.

Question 51

Describe the Bohr model of the atom.

Answer 51

The Bohr model of the atom proposed that electrons orbit the nucleus in spherical orbits, with 2 electrons in the first shell, 8 in the second, and so on.

Question 52

What are the sub energy levels in the model of atomic structure?

Answer 52

The sub energy levels in the model are labeled S, p, d, and f.

Question 53

Define orbitals in the model of atomic structure.

Answer 53

Orbitals are regions around the nucleus that hold up to a specific number of electrons. They are split into sub-levels, such as S, p, d, and f.

Question 54

Describe the shapes of orbitals in the model of atomic structure.

Answer 54

Orbitals represent the mathematical probabilities of finding an electron at any point within certain spatial distributions around the nucleus. Each orbital has its own approximate three-dimensional shape.

Question 55

How does an atom fill up sub shells in the model of atomic structure?

Answer 55

An atom fills up the sub shells in order of increasing energy. For example, the 3d sub shell is higher in energy than the 4s sub shell, so it gets filled after the 4s.