Periodicity- The First 20 Elements Flashcards
What of the first 20 elements have metallic bonding?
Li, Be, Na, Mg, Al, K, Ca
What ate the covalent molecular elements?
H², N², O², F², Cl², P⁴, S⁸ and fullerenes e.g. C⁶⁰
What are the covalent networks?
Boron, Carbon (graphite and diamond) and silicon.
What are the monatomic elements?
The noble gases (group 0)
What is the covalent radius?
Half the distance between the nuclei of two atoms joined by a single covalent bond.
What happens to the covalent radius going along a period?
It decreases. The number of screening shells of electrons is the same and the attraction of the nucleus for the outermost electrons gets stronger so the shells are held more close together.
What happens to the covalent radius going down a group?
It increases. As you go down a group, the number of electron shells occupied increases. This means that the inner shells screen the outermost electrons from the full pull of the positive nucleus which means the outer electrons can move further away.
What is ionisation energy?
The first ionisation energy is the energy required to remove an electron from every atom in a mole of atoms in a gaseous state.
What happens to the first ionisation energy going across a period?
It increases. As you go across a period, electrons are being added to the same energy level and at the same time protons being added to the nucleus. The electrons are then held more tightly so it is harder to remove outer electrons.
What happens to the first ionisation energy going down a group?
It decreases. This is because the covalent radius increases and the outer electrons are further away than the pull of the nucleus. The outer shell is also screened by the inner shells, reducing the pull of the nucleus. This results in it being easier to remove electrons.
What is electronegativity?
Electronegativity is the attraction an atom involved in a bond has for the electrons of the bond.
What happens to the electronegativity going across a period?
It increases. The nuclear charge on an atom increases. Therefore, the attraction for the bonding electrons increases. There is no screening effect of the inner electrons.
What happens to the electronegativity going down a group?
It decreases. The atoms get bigger going down a group, and the outer electrons are further from the attraction of the nucleus. The no. of shells increases going down a group so the screening effect increases.
