Periodicity Flashcards
(20 cards)
What does the period tell us how about the elements in that period
The highest energy electron shell is in the same number shell as the period
What is the electron configuration of boron
As you go one element across a period what changes
The amount of protons increase by one
Why can’t atomic radiuses be known completely
Because electron clouds don’t have a clear cut-off point
What happens to the atomic radius as you move across a period
Explain this trend
It decreases from left to right
This because the amount of protons increase by one each time you move to the right and the positive charge increases across the period
Because of this there is an increased electrostatic attraction between the nucleus and the outer electrons and this draws the electrons closer to the nucleus
What happens to the amount of shielding as you move across period 2
It stays the same
All elements in period 2 have only one inner electron shell so shielding due to the inner electron shell is the same across the period
What is the trend in atomic radius when moving down a group
It increases
Each element has one more full electron shell so the distance between the outer electron shell and the nucleus increases and there’s less attraction between the two
What is the definition of first ionisation energy
The energy needed to remove one mole of electrons from one mole of atoms in their gaseous state to form one mole of gaseous 1+ ions
What is the equation for the first ionisation energy of magnesium
What is the general trend of first ionisation energy across period 2 and what are the exceptions
General increase
Decrease from Be to B and from N to O
Explain the general trend of the first ionisation energy across a period
The atomic radius decreases because of an increased attraction between the outer electrons and the nucleus
This means more energy is required to remove these electrons from those atoms
Is shielding a factor when it comes to the trend in first ionisation energy across period 2 and why
No
Because each time an electron is being removed from the 2nd electron shell
Explain the exceptions for the trend in ionisation energy in period 2
From Be to B:
- In Be the outer electron is being removed from a 2s subshell
but in B it is being removed from a 2p subshell
- Which is higher in energy
From N to O:
- In N the electrons in 2p are in separate orbitals but in O there
is a orbital where there are two electrons together
- These electrons repel each other so it takes less energy to
remove one of these electrons than if the electrons were in
separate orbitals
What are the exceptions to the trend in first ionisation energy in period 3
Decrease from Mg to Al and from P to S
Explain the trend in first ionisation energy going down a group
Decreases, this is due to two reasons
Atomic radius increases and the attraction between the nucleus and the outer electron decreases
The number of internal electron shells increase so the amount of shielding increases and this causes the attraction to decrease
Describe and explain the shape of the graph of oxygen’s successive ionisation energies against ionisation energy
Gradual increase in ionisation energy from 1st to 6th ionisations because the electrons remaining are slightly pulled closer to the nucleus which causes a gradual increase in attraction between the nucleus and the outer electrons
There’s a spike in ionisation energy at the 7th ionisation - there are 6 electrons in the outer shell and once they are removed then in order to ionize the element you have to remove electrons from the inner electron which is much more attracted to the nucleus than the outer electron so the energy needed to ionize is much greater
Assuming that this element is in period 3 what is the element
There are four ionisations before the massive spike in ionisation energy so there are four electrons in the outer shell meaning that it’s in group 4
The element that is in period 3 and in group 3 is silicon
Explain metallic bonding
Metals are positive ions that have delocalised electrons
The electrostatic attraction between these two is metallic bonding
What is the structure of a metal called
Giant metallic structure
Explain the key features of a giant metallic lattice
The cations are fixed in place and cannot move
The delocalised electrons are free to move - this means that metals can conduct electricity when it is solid or liquid
Relatively high melting and boiling points - because of the strength of the metallic bond (lot of energy to overcome the electrostatic attraction)
Don’t dissolve
