Unit 1 - Periodicity Flashcards
what is the covalent radius?
half the distance between the nuclei of of two covalently bonded atoms.
why does the covalent radius decrease from left to right across a period?
there is more electrons in the outer shell and more protons in the nucleus and the greater attraction between the protons and electrons pulls the atom closer together
why does the covalent radius increase as you go down a group?
there is an extra outer energy level, the outer electrons are further away so are not as attracted to the positive charge.
what is ionisation energy?
the energy involved in removing one mole of electrons from one molel of atoms in the gaseous state.
why does ionisation energy increase from left to right across a period?
there is an increase in atomic charge which has a greater pull on the electrons and so more energy is required to remove electrons.
why does ionisation energy decrease as you go down a group?
the outer electrons are further away from the nucleus so the attraction is weaker and they are more easily removed.
what is electronegativity?
a measure of an atom’s attraction for the electrons in a bond
why does electronegativity increase from left to right across a period?
the atoms have a greater charge in their nucleus and a smaller covalent radius and this allows the nucleus to attract the bonding electrons more strongly.
why does electronegativity decrease as you go down a group?
atoms increase in size with a greater number of energy levels, this keeps the bonding electrons further away from the nucleus. This means that atoms further down groups have less attraction for the bonding electrons.
