Unit 1 topic 2 Periodicity Flashcards
State what is meant by the term Covalent Radius.
The covalent Radius is half of the distance between the nuclei of two bonded atoms of the element.
State what is meant by the term the first Ionisation Energy.
The first ionisation energy is the energy required to remove one mole of electrons from one mole of atoms in the gaseous state.
State what is meant by the term Electronegativity.
Electronegativity is the measure of the affinity the nucleus has for the bonding electrons.
As you go down a group the size of the atom increases, explain why.
This is because the number of occupied electron shells increases, this shields the electrons from the nuclear pull so they are not pulled in more tightly, therefore has a larger size.
As you go across a period the size of the atom increases, explain why.
The size of atom increases because as you go across a period the nuclear charge from the nucleus increases, this increases the nuclear pull from the nucleus on the electrons pulling them in closer resulting in a smaller size.
As you go down a group the First Ionisation Energy value decreases, explain why.
As you go down a group the First Ionisation Energy decreases because there are more occupied shells around the nucleus, this means the electrons are more shielded and the nuclear pull from the nucleus on the electrons is less and therefore it takes less energy to remove the electrons.
As you go across a period the First Ionisation Energy value increases, explain why.
As you go across a period the First Ionisation Energy increases because the nuclear charge across the period increases, this means that the electrons are being held more tightly and therefore it requires more energy top remove the electrons.
As you go down a group the electronegativity value decreases, explain why.
As you go down a group the Electronegativity value decreases because there are more occupied shells around the nucleus, this means the electrons are more shielded and the nuclear pull from the nucleus on the electrons is less and therefore it has a lower electronegativity.
As you go across a period the Electronegativity value increases, explain why.
As you go across a period the Electronegativity increases because the nuclear charge across the period increases, this means that the electrons are being held more tightly and therefore it has a higher electronegativity as it has a stronger pull on the electrons.
State what is meant by the term the second Ionisation Energy?
The second ionisation energy is the energy required to remove a further mole of electrons from a mole of ions in the gaseous state.
Write the equation for the second ionisation energy of Nitrogen.
N+(g) –> N2+(g) + e
Can you calculate the ionisation energy for
Mg(g) –> Mg3+(g) + 3e
Can you calculate the ionisation energy for
Al3+(g) + 3e –> Al(g)
For group 1 elements there is a significant increase from the first to the second ionisation energy.
Group 1 elements will have one electron in the outermost shell. It doesnt take so much energy to remove this as it is being removed from an occupied shell further away from the nucleus which is more shielded and requires less energy to remove the electron. When you go into the next shell to remove the second electron, you are removing an electron from a full stable shell that has less shielding, closer to the nucleus meaning there is more of a pull on theses electrons and it takes more energy to remove the electron.
Why is the covalent radius of sodium larger than the ionic radius of sodium?
This is because the covalent radius has three occupied shells, the electron arrangement is 2,8,1.
The Ionic radius has lost an electron and therefore only has two occupied energy shells therefore the ionic radius is smaller.
