2A.4 ionisation energies Flashcards
what is ment by ionisation
Ionisation is where an atom becomes an ion by gaining or losing an electron
what is Ionisation energy
Ionisation energy is the measure of energy needed to remove an electron from an atom of an element.
are Ionisation energies endothermic or exothermic
Ionisation energies are always endothermic – as energy is needed to remove electrons.
what is the first ionisation energy
The first ionisation energy of an element is the energy required to remove one electron from each atom in 1 mole of gaseous atoms to form 1 mole of gaseous 1+ ions (measured in kJ mol-1).
successive ionisation energies
it is when we can continue removing electrons and measuring the ionisation energies, You can then have asmany successive ionisation energiesas there are electrons in the original atom, then it can tell us how the electrons are arranged in the atom
what is the second ionisation energy
The second ionisation energy of an element is the energy required to remove an electron from each singly charged positive ion in 1 mole of positive gaseous ions to form 1 mole of gaseous 2+ ions. (measured in kJ mol-1)
what is the third ionisation energy?
The third ionisation energy of an element is the energy required to remove an electron from each doubly charged positive ion in 1 mole of positive gaseous ions to form 1 mole of gaseous 3+ ions. (measured in kJ mol-1)
how can successive ionisation energies prove quantum shells?
as we see the trend we notice that there are big irregular jump from of energy from some electrons to other breaking the trend this shows that the electrons are in different shells with different energies because of there position
Why do successive ionisation energies increase in magnitude?
- Electron lost during the first ionisation energy is far away from the influence of the nucleus and no longer experiences an attractive force from the nucleus.
- Energy of an electron has to be increased to a particular value to be removed.
- For any given atom the energy value the electron needs to reach before it is removed will always be the same, regardless of where in the atom the electron has come from.
- If an electron has high energy = it will not need to gain much energy to be removed.
If an electron is in an orbital of a low-energy quantum shell = then it will need to gain a lot more energy to be removed.
5.
Ionisation energy (IE) for a particular electron in a given atom depend on
the energy has when it is in its orbital in the atom.
what does (IE) equal to
Ionisation energy (IE) = energy of electron when removed – the energy of electron when in orbital.
what are 4 things to remember about electron-electron replustion
- it exists between two electrons in the same orbital
- exists between electrons in different orbitals within the quantum shell
- it is sometimes most significant between elections in adjacent quantum shells
- they are sometimes called screening or shelding
what are the 3 factors that affected the energy of an electron
- Nuclear Charge:
The more protons in the nucleus.
More positively charged the nucleus is and the stronger the attraction for the electron.
More energy needed to remove an electron.
Greater IE - Amount of repulsion (shielding) felt by electron from all other electrons:
More quantum shells/electrons
More repulsion (shielding) between electrons.
Weaker attraction between electron and nucleus.
Less energy is needed to remove an electron.
Smaller IE - Amount of repulsion (shielding) felt by electron from all other electrons:
More quantum shells/electrons
More repulsion (shielding) between electrons.
Weaker attraction between electron and nucleus.
Less energy is needed to remove an electron.
Smaller IE
what are the trends in IE
across a period: as we move across a period the number of protons would increasing making the first ionization energy more, also as we move across the period that’s one more electron, therefore, more electron-electron replustion so less IE but the nuclear charge is more effective therefore as we go across a period the IE is increased down a group: so as you go down a group there are more protons, therefore, a higher IE of the first electron, also as you go down the group we would have an electron on the next shell giving it more energy since (1s >2s>2p>3s) and there would be more electrons so more electron to electron repulsion. having these two effects combined would be more significant than the increase in nuclear charge so the IE of the first electron going down a group would decrease
what groups dont follow the IE trend (down the group)
group 4: Pb and tin dont follow the trend
group 3: B and thallium don’t follow the trend
