Periodicity Flashcards
what is the covalent radius
half the distance between the nuclei of 2 of its bonded atoms
what happens to the size of atoms as you go across a period
they decrease
why does the size of an atom decrease as you go across a period
as you go across a period the positive charge on the nucleus increases. The shells or energy levels of electrons are strongly attracted to the nucleus
what happens to the size of an atom as you go down a group
there is another electron shell so the size of the atom increases
what is the first ionisation energy of an element
the first ionisation energy of an element is the energy required to remove one mole of electrons from one mole of an atom in the gaseous state
what happens to the first ionisation energy as you go along a period
it increases
what happens for the first ionisation energy as you go down a group
it decreases
why does the ionisation energy increase going along a period
due to the increases nuclear charge across a period, outer electrons are held more tightly to the nucleus so more energy if required to remove them
why does the first ionisation energy decrease going down a group
going down a group the atomic size increases due to there being more energy shells. Inner electron shells shield the outer electrons reducing the attraction of the positive nuclear charge
why is the second ionisation energy always greater then the first
in the second ionisation energy negative electrons are being removed from positive ions, rather than neutral atoms. In the positive ion has a greater traction for the electron so more energy is required to remove the second mole of electrons
why is the second ionisation energy of K (2,8,8,1) greater then the second ionisation energy of Mg (2,8,2)
The second ionisation energy of K involves removing an electron from a stable electron arrangement, this requires a lot of energy. Whereas the second ionisation energy of Mg involve removing an electron from an unstable electron arrangement this requires less energy
