2.2 Evidence For Electronic Structur Flashcards
Define first Ionisation energy
The energy needed to remove 1 mole of electrons from 1 mole of atoms of an element in the gaseous state to form 1 mole of gaseous ions
How is the ionization energy of an element calculated
By firing high speed electrons at atoms that will knock out one electron from each atom
Ionization energy are measured under
Standard conditions
The general symbol for ionization energy is
IE
The units for ionization energy are
kJ mol^-1
Write the chemical equation for first ionization energy using Calcium
Ca(g) —> Ca+(g) + e-
Write the chemical equation for second ionization energy using Calcium
Ca+(g) —> Ca2+(g) + e-
Define succesive ionization energy
The energy required in each step to remove the first electron, then the second and so on from a gaseous atom (until only the nucleus is left).
— the sequence of ionization energies
Describe the pattern of successive ionization energies for each element and explain why
The successive ionization energies increase because the net positive charge on the ions get greater as each electron is removed. As each electrons is removed there is a greater positively charged protons in the nucleus and the remaining negatively charged electrons. Therefore more energy is needed to overcome these attractive forces.
Explain why there is a big difference between some succesive ionization energies
These large changes indicate that for the second of these two ionization energies, the electron is being removed from a principal quantum shell closer to the nucleus
How does the size of nuclear charge influence the ionization energy
As the atomic number increases, the positive nuclear charge in the nucleus increases. The greater the attractive force between the nucleus and the electrons. So, more energy is needed to overcome the attractive forces if an electron is to be removed.
How does the size of nuclear charge influence the ionization energy
As the atomic number increases, the positive nuclear charge in the nucleus increases. The greater the attractive force between the nucleus and the electrons. So, more energy is needed to overcome the attractive forces if an electron is to be removed.
How does the distance of outer electrons from the nucleus affect the ionization energy
The force of attraction between positive and negative charge decreases/weakens as the distance between them increases. Hence the further away the electrons are from the nucleus, the lower their ionization energy.
How does shielding effect of ionization energy affect
As all electrons are negatively charged, they repel each other. Electrons in full inner shells repel electrons in outer shells. Full inner shells of the electrons prevent the outer electrons feeling the full nuclear charge. (This called shielding.) The greater the shielding of outer electrons by inner electrons shells, the lower the attractive forces between the nucleus and outer electrons, the less energy required you knock out the electrons.
The ionization energy is lower as the number of full electron shells between the outer electrons and the nucleus increases.
How does the spin pair repulsion affect the ionization energy
Electrons in the same atomic orbital in a sub shell repel each other more than electrons in different atomic orbitals. This increased repulsion makes it easier to remove an electron.
