ATOMIC STRUCTURE Flashcards
Describe the process of Electron-Impact Ionisation
Sample is vapourised
High-energy electrons are fired at sample
from an electron gun
One electron is knocked off each particle
Give two reasons why it is necessary to ionise the isotopes of chromium before they can be analysed in a TOF mass spectrometer.
accelerated/Allow (ions) accelerated to a negative plate
ions create a current in the detector by picking up an electron
Allow (ions) can be detected
Explain why the ionisation energy of every element is endothermic
Heat or energy needed to overcome the attraction between the (negative) electron and the (positive) nucleus or protons
Explain why the second ionisation energy of boron is higher than the first ionisation energy of boron 1
Second electron is removed from a positive ion
what did Rutherford discover and through what experiment evidence is there
discovered nucleus and that’s its very small and most atom is empty space
Rutherford fired He2+ ions at a sheet of gold foil. most went through bcz atom is mostly empty space and small number of them deflected back because of the small positive nucleus
what did bohr discover
electrons in enegy shells
why is the second IE of boron is higher than the first IE of boron 2
forms a positive ion
more protons compared to electrons due to electron loss
attraction over remaining electrons is stronger therefore requires more energy
why is the second IE of rubidium larger than the second IE of strontium 2
WRITE ELECTON CONFIGURATION OUT
Rb - 2nd e- removed from a shell closer to the nucleus (lower energy level)
stronger nuclear attraction for Rb e-
Explain why the second ionisation energy of calcium is lower than the second ionisation energy of potassium 2.
DO ELECTRON CONFIGURATION so know which electron is being removed
In Ca(+) (outer) electron(s) is further from nucleus
More shielding (in Ca+
Deduce which of Na+ and Mg2+ is the smaller ion.
Explain your answer.
Mg(2+) or Magnesium
Because Mg2+ has more protons
AND
With the same shielding/ screening/electron arrangement/ number of electrons (or isoelectronic)
Allow larger/stronger nuclear charge
Ignore atomic radiu
State the meaning of the term first ionisation energy of an atom.
energy change/required when a mole of electrons is removed/ knocked out / displaced/ to form a positive ion
from a mole of gaseous atoms
Explain why the value of the first ionisation energy of neon is higher than that of sodium. 2
Electron removed from a shell of lower energy or smaller atom or e– nearer to nucleus
Less shielding
In terms of the electron sub-levels involved, explain the position of aluminium and the position of sulphur 4
AL outer electron in (3)p sub-shell
Sub-shell further away from nucleus OR of higher energy level so easier to remove e-
Explanation for sulphur: Pair of electrons in (3)p orbital
Repulsion between electrons
(4
A student studying GCSE science is puzzled by data which indicate that a sodium atom is larger than a chlorine atom and that a sodium ion is smaller than a chloride ion. How should an A–level Chemistry student explain this apparently conflicting information. 6
A chlorine atom has more protons in its nucleus than a sodium atom has
Both have three shells of electrons
Electrons more strongly attracted by chlorine nucleus so size smaller than Na
An electron shell is lost when a sodium ion is formed from a sodium atom
Inner electrons more strongly attracted so ion smaller than atom
An electron is added to the outer shell when a chloride ion is formed
Greater repulsion between shells so size of chloride ion greater than Cl atom
Explain why the value of the first ionisation energy of sulfur is less than the value of the first ionisation energy of phosphorus. 2
Paired electrons in (3)p orbital
repel
