Electron arrangement and ionisation energy L2,3 Flashcards
What are the key differences between Thompson’s model and Bohr’s model?
Bohr model (current model compared to plum pudding) has a small positive nucleus
The electrons are in energy shells surrounding the nucleus
(We now know that the nucleus also has neutrons)
What did Rutherford conclude when He2+ ions went straight through the gold sheet.
When the He2+ ions went through the middle he concluded that most of the atom was empty space
Why did a small number of He+ ions deflect in Rutherford’s experiment? And what did he conclude?
He2+ has no electrons is only a positive ion. Same charges repel eachother therefore Rutherford concluded that the atom must have a small positive nucleus.
Define ionisation energy.
Is the amount of energy needed to remove a mole of electrons from a mole of atoms, in a gaseous state
What are the units for ionisation energy
KJ/mol
Write an equation for the 1st ionisation energy of Magnesium
Mg(g) – Mg+(g) + e-
Note: always forms a positive ion and loses an electron
What are the three key factors that will influence ionisation energy?
1.Nuclear charge- the number of protons in the nucleus
2. Distance from the nucleus
3. Shielding
How does the nuclear charge influence ionisation energy?
Nuclear charge is the number of protons in the nucleus:
therefore more protons
means there will be a stronger electrostatic attraction
therefore more energy is required to remove outer-most electrons
Will the IE across a period increase or decrease when thinking about how nuclear charge?
Will increase as the atomic number- proton number- increases
How does the distance from the nucleus influence IE?
If an electron is closer to the nucleus
there is a stronger electrostatic attraction
therefore more energy is required to remove the electron
How does shielding influence IE?
If electrons are on a shell furthest from the nucleus
there is more shielding
therefore weaker attraction
less energy required to remove outermost electron
Does the IE down a group decrease or increase when thinking about shielding?
IE down a group decreases because there are more energy shells less energy required to remove the electrons
Blocks attractions if there is more shielding
As you go down a group will the IE increase or decrease when thinking about the distance from the nucleus?
IE will decrease down the group bc the distance increases from the outermost shell, more shells
What is meant by successive ionisation energies?
One after the other
Does the removal of electron -1st IE occur at the outermost electron or the electron closest to the nucleus?
The outer most electron
