Flashcards in Atomic Structure Deck (30)
Isotopes are atoms with the same number of protons, but different numbers of neutrons
What are the chemical and physical properties like with isotopes?
Similar chemical but different physical properties
What does m/z stand for?
Describe the four steps for how positive ions are formed during electron impact
1. A Vaporised sample is injected at low pressure
2. An electron gun fires high energy electrons at the sample
3. This Knocks out an outer electron
4. Forming positive ions with different charges, e.g. Ti(g) => Ti*(g) + e-
Describe the five steps of electro-spray ionisation
1. The sample is dissolved in a volatile, polar solvent
2. It is then injected through a fine hypodermic needle giving a fine mist or aerosol.
3. The tip of needle has high voltage
4. At the tip of the needle the sample molecule, M, gains a proton, H+, from the solvent forming MH+
5.M(g) + H* => MH*(g)
6.The solvent evaporates away, while the MH* ions move towards the negative plate
What is the kinetic energy like with particles in the TOF spectrometer?
What is the equation for measuring the kinetic energy in TOF spectrometry?
KE= ½ m v2
Rearrange the kinetic energy equation to make velocity ‘v’ the subject of the formula
v = (square root of) 2KE / m
Which type of particles move faster through the flight tube?
Write the combined equation for the kinetic energy of a particle travelling through a flight tube
t = distance x (square root of) m / 2KE
Write the equation for working out the relative atomic mass
Sum(isotopic mass x relative abundance)/ total relative abundance
Br has two isotopes 79 and 81. It forms 3 peaks: 158, 160 and 162. How was each of these 3 peaks formed?
158= 79 + 79
160= 79 + 81 or 81+ 79
162= 81 + 81
Br has two isotopes- 79 and 81. Why is the abundance at 160 double that of 158 and 162?
13. Can either be 79 + 81 or 81+ 79
The mass of a molecule is 521.1 for MH+. Electro spray ionisation was used. What is the Mr of the molecule?
How many electrons does s,p,d and f sub energies hold?
How many electrons does an orbital hold?
Write the sub levels for an atom ending with 5p (i.e. 1s,2s etc). You don’t need to include the number of electrons
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p
What is the rough outline of the periodic table. Label: S-block, d-block, p-block and f-block?
S on left, d in middle, p on right, f at the bottom
Define first ionisation energy
The first ionisation energy is the enthalpy change when one mole of gaseous atoms forms one mole of gaseous ions with a single positive charge
Write the first ionisation energy of Hydrogen including state symbols
H(g) => H*(g) + e-
Write the second ionisation energy of Titanium including state symbols
Ti*(g) => T*2(g) + e-
What are the 3 factors affects ionisation energy?
Attraction of the nucleus
Distance of the electrons from the nucleus
There is a large jump in ionisation energies between 4 electrons removed and 5. What does this mean for the group number?
It must be Group 4
In a spin box, how many arrows are there?
2 (one up and one down)
Why has Helium the largest first ionisation energy?
It's first electron is in the first shell closest to the nucleus and there are no shielding effects from inner shells.
He has a bigger first ionisation energy than H as it has one more proton.
Why do first ionisation energies decrease down a group?
As one goes down a group, the outer electrons are found in shells further from the nucleus and are more shielded so the attraction of the nucleus becomes smaller
Why is there a general increase in first ionisation energy across a period
As one goes across a period the electrons are being added to the same shell which has the same distance from the nucleus and same shielding effect. The number of protons increases, however, making the effective attraction of the nucleus greater.
Why has Na a much lower first ionisation energy than Neon?
This is because Na will have its outer electron in a 3s shell further from the nucleus and is more shielded. This means there will be a weaker nuclear attraction and So Na’s outer electron is easier to remove and has a lower ionisation energy.
Why is there a small drop from Mg to Al?
Al is starting to fill a 3p sub shell, whereas Mg has its outer electrons in the 3s sub shell. The electrons in the 3p sub-shell are slightly easier to remove because the 3p electrons are higher in energy and are also slightly shielded by the 3s electrons.