1.1 Atomic Structure Flashcards
Draw a table showing the relative mass and charge of a: Neutron, Proton and Electron.
(see page 2 in the revision guide)
What are ions?
Ions have different numbers of Protons and electrons.
see page 2 in the revision guide for some examples
What are isotopes?
Isotopes are atoms of the same element, the same number of protons with different numbers of Neutrons.
(see page 3 in the revision guide for an example)
What decides the chemical properties of an element?
The number and arrangement of electrons decides the chemical properties of an element.
(see page 9 in the revision guide for my information)
What decides the physical properties of an atom?
The physical properties of an atom tends to depend on the mass of the atom.
Describe how the model of the atomic structure has changed throughout history.
(see page 4 in the revision guide)
What is the relative atomic mass?
The relative atomic mass (Ar) is the average mass of an atom of an element on a scale where an atom of carbon-12 is 12.
(see page 5 in the revision guide to see how to calculate this)
What is the relative isotopic mass?
The relative isotopic mass is the mass of an atom of an isotope of an element on a scale where an atom of carbon-12 is 12.
(see page 5 in the revision guide to see how to calculate this)
What is the relative molecular mass?
The relative molecular mass (Mr) is the average mass of a molecule on a scale where an atom of carbon-12 is 12.
(see page 5 in the revision guide to see how to calculate this)
Describe the 4 steps a Mass Spectrometer used to measure mass:charge ratio of an element.
- Ionisation
- Acceleration
- Ion Drift
- Detection
(see page 5 in the revision guide for a description of each)
What is a Mass Spectrum?
A Mass Spectrum is Mass/Charge plotted against abundance.
see page 6 in the revision guide for a diagram and more descriptions
How do you calculate the relative atomic mass of an element from the mass spectrum?
(see page 6 in the revision guide)
How can Mass Spectrometer be used to identify elements?
(see page 6 in the revision guide)
How can Mass Spectrometer be used to identify molecules?
(see page 7 in the revision guide)
What is he number of orbitals and maximum number of electrons in each sub-shell?
(see page 8 in the revision guide)
Read the bottom of page 8.
Do you know and understand this section?
How do Chromium (Cr) and Copper’s (Cu) electronic structure behave differently to other elements?
(see page 9 in the revision guide)
Define the first ionisation energy.
The first ionisation energy is the energy needed to remove 1 electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions.
Write the equation for the first ionisation energy of oxygen.
(see page 10 in the revision guide and read it all)
What factors affect ionisation energy?
1) Nuclear charge
2) Distance from the nucleus
3) Shielding
- (see page 10 in the revision guide for details about each)
Define the second ionisation energy.
The second ionisation energy is the engird needed to remove 1 electron from each ion in 1 mole of gaseous 1+ ions to form 1 mole of gaseous 2+ ions.
Write an equation for the second ionisation energy of oxygen.
(see page 10 in the revision guide and read it all)
How do successive ionisation energies show cell structure?
(see page 11 in the revision guide)
What happens to the first ionisation energies of elements going down a group?
They decrease.
read page 12 in the revision guide
What happens to the first ionisation energies of elements going across a period?
The generally increase.
read page 12 in the revision guide
Why do isotopes have similar chemical properties?
Because they have the same electronic structure.
Why do isotopes have slightly varying physical properties/
Because they have different masses.
What is a chemical property?
A chemical property is a characteristic or behavior of a substance that may be observed when it undergoes a chemical change or reaction.
What is a physical property?
A characteristic that may be observed and measured without changing the chemical identity of a specimen.
List the four parts to a Time of Flight (TOF) Mass Spectrometer.
- Ionisation
- Acceleration
- Ion drift
- Detection
When is a TOF mass spectrometer used?
The mass spectrometer can be used to determine all the isotopes present in a sample of an element and to therefore identify elements.
Why does TOF mass spectrometry need to be under a vacuum?
Otherwise air particles would ionise and register on the detector.
What two ways can a sample be ionised?
- Electron impact
- Electro spray ionisation
Describe Electron impact.
- A vaporised sample is injected at low pressure
- An electron gun fires high energy electrons at the sample
- This knocks out an outer electron
- Forming positive ions with different charges
E.g. Ti(g) ->Ti+(g) + e-
Describe Electro spray ionisation.
- The sample is dissolved in a volatile, polar solvent
- Injected through a fine hypodermic needle giving a fine mist or aerosol
- The tip of the needle has a high voltage
- At the tip of the needle the sample molecule, M, gains a proton, H+, from the solvent forming MH+
- M(g) + H+ -> MH+(g)
- The solvent evaporates away while the MH+ ions move towards a negative plate.
When is Electron impact used?
For elements and substances with low formula mass. Electron impact can cause larger organic molecules too fragment.
When is Electro spray ionisation used?
Preferably for larger organic molecules. The ‘softer’ conditions of this technique mean fragmentation does not occur.
Describe acceleration.
- Positive ions are accelerated by an electric field
- To a constant kinetic energy
Rearrange this equation to calculate the velocity of the particles in a TOF max spectrometer.
KE = 1/2 m v^2
v = √2KE/m
KE = Kinetic energy of the particle (J) m = Mass of the particle (kg) v = velocity of the particle(ms-1)
Do lighter particles have a slower or faster velocity than heavier particles in a TOF mass spectrometer?
Given that all the particles have the same kinetic energy, the velocity of each particle depends on its mass.
Lighter particles have a faster velocity, and heavier particles have a slower velocity.
How are ions distinguished in a TOF mass spectrometer?
The ions are distinguished by different flight times.
- Heavier particles take longer to move through the ion drift area in the flight tube.
- Smaller m/z ratios will move faster
Give the equation of how you calculate TOF in a TOF mass spectrometer.
t = d√m/2KE
t = time of flight (s) d = length of flight tube (m) v = velocity of the particle (ms-1)
Describe detection in TOF mass spectrometry.
The ions reach the detector and generate a small current, which is fed to a computer for analysis. The current is produced by electrons in transferring from the detector to the positive ions. The size of the current is proportional to the abundance of the species.
What does a TOF mass spectrometer measure?
For each isotope, the mass spectrometer can measure a m/z (mass/charge ratio) and an abundance.
What would the m/z ratio be of a Mg2+ ion?
24/2
m/z = 12
Answer the question on page 2 of chemrevise revision guide.
correct?
What is the relative atomic mass an average of?
The relative atomic mass is a weighed average of all the isotopes of that element.
Give the equation for calculating relative atomic mass, when given % abundance.
R.A.M = ∑ (isotopic mass x %abundance) / 100
Give the equation for calculating relative atomic mass, when given relative abundance.
R.A.M = ∑ (isotopic mass x relative abundance) / total relative abundance
Answer the 2 questions on page 3 in the chemrevise revision guide.
correct?
How many electrons can sub-level s hold?
up to 2 electrons
How many electrons can sub-level p hold?
up to 6 electrons
How many electrons can sub-level d hold?
up to 10 electrons
How many electrons can sub-level f hold?
up to 14 electrons
What sub-levels are in the principle energy level 1?
1s
What sub-levels are in the principle energy level 2?
2s, 2p
What sub-levels are in the principle energy level 3?
3s, 3p, 3d
What sub-levels are in the principle energy level 4?
4s, 4p, 4d, 4f
What actually are orbitals?
Orbitals represent the mathematical probabilities of finding an electron at any point within certain spatial distributions around the nucleus.
What is the shape of s sub-level orbitals?
spherical
What is the shape of p sub-level orbitals?
figure of 8
Give the order of increasing energy of the electronic sub shells.
1s, 2s, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p
- 3d is higher in energy than 4s so gets filled after the 4s
Write the electronic structure of oxygen.
1s2 2s2 2p4
Write the electronic structure of calcium.
1s2 2s2 2p6 3s2 3p6 4s2
Use a spin diagram to write the electronic structure of fluorine.
(see page 5 in the chemrevise revision guide)
What do the arrows going in opposite directions represent in a spin diagram?
It represents the different spins of the electrons in the orbital.
What do all the elements in s block have in common on the periodic table?
An s block element is one whose outer electron is filling a s-sub shell.
e.g. sodium 1s2 2s2 2p6 3s1
What do all the elements in d block have in common on the periodic table?
A d block element is one whose outer electron is filling a d-sub shell.
e.g. vanadium 1s2 2s2 2p6 3s2 3p6 4s2 3d3
What do all the elements in p block have in common on the periodic table?
A p block element is one whose outer electron is filling a p-sub shell.
e.g. chlorine 1s2 2s2 2p6 3s2 3p5
Draw where s, p, d and f blocks are on the periodic table.
(see page 6 in the chemrevise revision guide)
Draw the electron structure for Mg and Mg2+
Mg = 1s2 2s2 2p6 3s2 Mg2+ = 1s2 2s2 2p6
When a positive ion is formed, electrons are lost from the outermost shell.
Draw the electron structure for O and O2-
O = 1s2 2s2 2p4 O2- = 1s2 2s2 2p6
When a negative ion is formed, electrons are gained.
Draw the electronic structure of Sc and Sc3+
(see page 6 in the chemreivse revision guide)
Draw the electronic structure of Ti and Ti3+
(see page 6 in the chemreivse revision guide)
Draw the electronic structure of V and V3+
(see page 6 in the chemreivse revision guide)
Draw the electronic structure of Cr and Cr3+
(see page 6 in the chemreivse revision guide)
Draw the electronic structure of Mn and Mn2+
(see page 6 in the chemreivse revision guide)
Draw the electronic structure of Fe and Fe3+
(see page 6 in the chemreivse revision guide)
Draw the electronic structure of Co and Co2+
(see page 6 in the chemreivse revision guide)
Draw the electronic structure of Ni and Ni2+
(see page 6 in the chemreivse revision guide)
Draw the electronic structure of Cu and Cu2+
(see page 6 in the chemreivse revision guide)
Draw the electronic structure of Zn and Zn2+
(see page 6 in the chemreivse revision guide)
Give the definition of the first ionisation energy.
The first ionisation is the enthalpy change when one mole of gaseous atoms forms one mole of gaseous ions with a single positive charge.
Write the equation for the first ionisation energy of hydrogen.
H(g) -> H+(g) + e-
Give the definition of the second ionisation energy.
The second ionisation energy is 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.
Write the equation for the second ionisation energy of titanium.
Ti+(g) -> Ti2+(g) + e-
What three factors affect ionisation energy?
- The attraction of the nucleus.
- The more protons in the nucleus, the greater the attraction. - The distance of the electrons from the nucleus.
- The bigger the atom, the further the outer electrons are from the nucleus and the weaker attraction to the nucleus. - Shielding of the attraction of the nucleus.
- An electron in an outer shell is repelled by electrons in complete inner shells, weakening the attraction to the nucleus.
What information does the patterns in successive ionisation energies for an element give us?
The patterns in successive ionisation energies for an element give us important information about the electronic structure for that element.
Why are successive ionisation energies always larger than the first ionisation energy?
When the first electron is removed, a positive ion is formed. The ion increases the attraction on the remaining electrons and so the energy required to remove the next electron is larger.
Describe the reason for the jump in the graph on page 7 in the chemrevise revision guide.
Explanation on page 7 in the chemrevise revision guide.
Answer the example question on page 7 in the chemrevise revision guide.
Answer is on page 7 in the chemrevise revision guide.
Draw an ionisation energy graph for:
H, He, Li, Be, B, C, N, O, F , Ne, Na, Mg, Al, Si, P, S, Cl, Ar, K, Ca
(see page 8 in the chemrevise revision guide)
Answer the questions on page 8 in the chemrevise revision guide.
correct?
How does the patterns in the second ionisation energy graph of elements differ to the patterns in the first ionisation energy?
The graph of the second ionisation energy will have a similar pattern to the first ionisation energy, but all the elements will have shifted one to the left.
(see page 9 in the chemrevise revision guide for a diagram)
