Topic 3.1.1.1 - Atomic Structure Flashcards
What is the relative atomic mass of a proton?
1
What is the relative atomic mass of a neutron?
1
What is the relative atomic mass of an electron?
Approximately 0
What is the relative atomic charge of a proton?
+1
What is the relative atomic charge of a neutron?
0
What is the relative atomic charge of an electron?
-1
What is the difference between two isotopes?
The number of neutrons, (or the mass number).
What are the similarities between two isotopes?
The number of protons and electrons, (or the atomic number).
What are the three fundamental particles that make up an atom?
Proton, neutron and electron.
Why is are the chemical properties of two different isotopes of the same element identical?
They have the same electron configuration.
What are the four stages of a mass spectrometer?
Electrospray Ionisation
Acceleration
Ion Drift
Detection
Which two stages of the mass spectrometer require the sample to be ionised?
Acceleration
Detection
Describe the process of electrospray ionisation in a TOF Mass Spectrometer
The sample is dissolved in a polar solvent and a high voltage is applied, causing the particles to lose an electron.
Describe the process of acceleration in a TOF Mass Spectrometer.
The positive ions are accelerated by an electric field.
Describe the relationship between the mass/charge ratio of an ion and it’s time spent during the electron drift phase of a TOF Mass Spectrometer.
The heavier the particle, the lower the speed and the greater the time taken to reach the detector.
Describe the process of detection in a TOF Mass Spectrometer.
The ions create a current when they reach the detector. The detector records the time taken to reach it and the current. The greater the abundance of the isotope, the larger the current.
What is the definition of relative atomic mass?
The relative atomic mass of an atom is the ratio of the average mass of one atom of that element to 1/12th of the mass of one atom of carbon-12.
What is the definition of relative molecular mass?
The relative molecular mass of a molecule is the ratio of the average mass of that molecule to 1/12th of the mass of an atom of carbon-12.
What is the charge on any molecule which passes through a mass spectrometer?
Positive
The relative atomic mass of a sample of magnesium is 24.46
The isotopes which make up the sample are Mg-24 (75.86%), Mg-25 (13.12%) and one other isotope. Calculate the mass of the missing isotope.
Missing Percentage = 100 - (75.86 + 13.12) = 11.02
24.46 = [ (24 x 75.86) + (25 x 13.12) + ( ? x 11.02) ] / 100
2446 = 1820.64 + 328 + (11.02 x ? )
297.54 = 11.02 x ?
27 = ?
Calculate the relative atomic mass of a sample of sodium consisting of the following isotopes: Na-22 (23.14%), Na-23 (59.16%) and Na-25 (17.70%).
RAM = [ (22 x 23.14) + (23 x 59.16) + (25 x 17.70) ]
RAM = [ 509.08 + 1360.68 + 442.5 ] / 100
RAM = 2312.26 / 100
RAM = 23.12
Calculate the relative atomic mass of a sample of hydrogen consisting of the following isotopes: H-1 (96.13%), H-2 (2.11%) and H-3 (1.76%).
RAM = [ (1 x 96.13) + (2 x 2.11) + (3 x 1.76) ] / 100
RAM = [ 96.13 + 4.22 + 5.28 ] / 100
RAM = 105.63 / 100
RAM = 1.06
What is the electron configuration of carbon?
1s2 2s2 2p2
What is the electron configuration of magnesium?
1s2 2s2 2p6 3s2
What is the electron configuration of vanadium?
1s2 2s2 2p6 3s2 3p6 4s2 3d3
What is the electron configuration of copper?
1s2 2s2 2p6 3s2 3p6 4s1 3d10
What is the electron configuration of Na+ ion
1s2 2s2 2p6
What is the electron configuration of the Br- ion?
1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6
What is the electron configuration of the Cr3+ ion?
1s2 2s2 2p6 3s2 3p6 4s0 3d3
What is the general trend in first ionisation energies across period 2?
Increase
What is the reason for the general increase in first ionisation energy across period 3?
The shielding remains constant along the period, but the amount of protons in the nucleus increases.
This means the effective nuclear charge increases across the period and so the electrons are held more tightly. Therefore the amount of energy required to remove the electrons increases.
Why does lithium have a higher first ionisation energy than sodium?
Sodium has its outer electron in 3s, whereas lithium has its outer electron in 2s. Sodium therefore has more shielding so the electrons are less tightly held and so require less energy to remove.
Why does aluminium have a lower first ionisation energy than magnesium?
Aluminium has its outer electron in the 3p orbital, which is slightly more shielded from the nucleus. Therefore the outer electron is less tightly held and so it requires less energy to remove the electron.
Why does oxygen have a lower first ionisation energy than nitrogen?
Oxygen has 4 electrons in the 2p orbital, so this is the first time in 2p where spin-pair repulsion occurs.
Because the electrons are already being repelled away from the atom, they require less energy to remove.
Why is the second ionisation energy of lithium higher than the first ionisation energy of lithium?
After the first ionisation energy, there are more protons in the nucleus than there are electrons in the atom. This means the electrons are more tightly held by the nucleus, and therefore to remove another electron requires even more energy.
