Atomic Structure Peq's Flashcards
What is the trend in the first ionisation energy of group 2 elements
Decreases as the ions get bigger therefore there is a weaker attraction of ions to lost electrons
Why is it necessary to ionise molecules when measuring their mass in a Tof mass spec
So the ions will interact with and be acceelerated by a electric field only ions will create current and be detected
Which of the elements magnesium or aluminium has the lower ionisation energy
Aluminium as the outer electron is in a p orbital and can be removed easily
What requires more energy for the outer electron to be removed an ion or an atom
An ion as it is already stable more preferably with less energy so a smaller ion. A electron can be removed more easily if it is in a higher orbital
State the element in period 3 with the highest melting point
Silicon as it contains many covalent bonds which may require lots of energy to be removed
State the element in period 3 with the highest electronegativity or highest first ionisation energy
Argon as it has the highest nuclear charge- most numbers of protons compared to others and the same number of electron shells and shielding etc
What is electronegativity
The ability of an atom to attract a pair of electrons towards itself within a covalent bond
Suggest the element in period 3 with the highest electronegativity value
Chlorine
What is not deflected by a electric field protons or neutrons or electrons
Neutrons
Explain why the second ionisation energy for boron is higher then the first energy
Because the electron is removed from a positive ion so it needs more energy to be removed, and it is closer to the nucleus.
Explain it terms of its structure and bonding why nickel has a strong mp
It contains positive metal ions and delocalised electrons, there is a strong attraction between them (metallic bond) hence more energy is required to overcome them.
Explain why nickel is ductile
As it has layers of atoms which can slide over each other.
Why is the second ionisation energy of silicon lower than the second ionisation energy of aluminium
As the electron in silicon is removed from a 3p orbital and there is more shielding so it is lost easier
Predict the element in period 3 that has the highest 2nd ionisation energy and why
Sodium as the electrons removed are nearer to the nucleus so it is harder to remove
Why is the ionisation energy of every element endothermic?
As heat energy is required to overcome the attraction between the negative electrons and the positive nucleus
State what can be adjusted in the mass spec to enable ions formed by the different isotopes to be directed onto the detector
The electric field or electromagnet
Name one instrument which is used to measure the relative abundance of isotopes
Mass spectometer
If it wants the 95 percent yield of something in an equation but gives you hypothetically 100 percent how do you work out the mass of it
You basically get the element we’re provided information for and use it and work out its moles. That moles is for 100 percent of it so we work out 95 percent so do that /95 times 100 to get 95 percent. And whatever moles you get is what you need to work with for the rest of the equation doing what you need to it for example using the molar ratio working out its mass whatever.
Write an ionic equation with state symbols to show the reaction of calcium with excess water
Ca(s)+2h20(l)—>ca2+(aq)+20H-(aq)+h2(g)
Give the electronic config of cr3+
Chromium= 4s1 3d5
Cr+=4d0 3d5
Cr2+=3d4
So cr3+ is (Ar)3d3
State the two measurements that are recorded for each isotope
- relative abundance
- m/z
Explain how the relative abundance of an ion is measured in a mass spec
The ions hit the detector picking up an electron allowing a current to be generated as a movement of charge occurs. The bigger the current the higher the abundance of ions.
A sample of rubidium contains the isotopes 85rb and 87rb only. The isotope 85 rib has an abundance 2.5 times greater than that of 87rb.
Calculate the ram of rubidium in this sample
You do
(85 times 2.5) + (87 times 1)
———————————————-
3.5
3.5 as you add 2.5 and 1
State and explain how al and s deviate from the general trend
Al as an electron is removed from 3p which is a higher sub shell so can be lost easier
S- as the electron is removed from a 3p electron pair so repulsion between e- means lost easier
Name 3 processes that occur in a mass spectrometer before detection and explain how
Ionisation- high energy electrons fired at the sample knocking off an outer electron
Acceleration- electric field
Deflection- due to the magnetic field
25mg atoms make up 10 percent by mass in a sample of magnesium magnesium has an ar of 24.3 use this to deduce the percentages of the other two magnesium isotopes present in this sample (mg26 and mg24)
So, 24.3=(25 times 10)+(24 times x) +(26times 90-x) bc the other two obviously are 90 so x and 90-x. Then re arrange it so 2430=250 times 24x times 2340-26x/100 then times by 100 - number divide by 2 and you should get x as 80 which means 90-80 is 10 so the other one is 10
If it gives you two mass numbers of isotopes and 2 relative abundance’s use this info to work out the relative abundance and the mass of the third isotope if total ram is 32.16
You do the first mass and abundance times the second one and for the third one (write the mass as x and the relative abundance do the previous two-100) so you get x and whatever number over 100. Then re arrange and solve for x. There you go thats your mass number
Define ionisation energy
Energy required to remove 1 outer electron from each atom in 1 mole of gaseous atoms to form one mole of gaseous ions
What do you have to add with ionisation energy equations
The gas state symbol bc remember their gases. Eg Mg+(g)—>Mg2+ +e-
Why does it take more energy for the second ionisation energy of mg
As the electron is being removed from a positive ion so the electron is being removed closer to the nucleus
Explain how the ions are held together in solid sodium metal
Strong electrostatic forces of attraction between the positive ions and the negative delocalised electrons.
Explain how ions are held together in solid sodium chloride
Electrostatic forces of attraction between oppositely charged ions
Why does sulfur deviate from the general trend of first ionisation energies
As there are two electrons in a 3P orbital which repel each other.
Which element deviates from a general trend from the period 2 elements
Boron/oxygen
Suggest why the iron (III) oxide obtained is pure, assume a complete reaction
As all other products are gases(will escape and not contaminate iron iii oxide)
Why is the na+ ion smaller than the f- ion
As it contains more protons so has a stronger attraction for its outer electrons and so is smaller in size
And both na+and f- have the same electron arrangement so similar shielding
Why would smth have a large atomic radius
If it has less protons as then there is less attraction between protons and electrons.
When would something have a smaller atomic radius
When it has a higher nuclear charge, bc more attraction between protons and electrons
Deduce the element in period 2 that has the highest second ionisation energy
Lithium - small when ion hard to remove the electron greater attraction between ion and lost electrons
describe how ions are formed in a tof mass spectrometer
Apply high voltage, atoms lose electrons
explain electrospray
sample dissolved in a volatile solution, injected through needle at high pressure EACH MOLECULE gains a proton
the first ionisation energies of the elements in period 2 change as the atomic number increases. explain the pattern in the first ionisation energies of the elements from lithium to neon (6 marks)
first ionisation energies increase along the row, nuclear charge increases and greater attraction between nucleus and outer electrons making it harder to remove the electrons and shielding is similar
deviation between be and b. b’s first ie is lower than be as it is in the 2p subshell which is higher in energy meaning that electron can be removed
deviation between n and o easier to remove electrons in o because 2p subshell contains electron pair which causes repulsion meaning the electron is easier to remove
state two measurements recorded for each isotope
m/z and abundance
explain why the ionisation energy for every element is endothermic
as heat energy is required to overcome the attraction between the positive nucleus and the negative electrons
explain why chromium is placed in the d block in the periodic table
as its outer electron or highest energy electron is in the 3d subshell, or has an incomplete d subshell
