electronic structure Flashcards
what is meant by Pauli’s exclusion principle?
no two electrons in an atom have the same four quantum numbers
what is meant by Hund’s rule?
electrons fill orbitals singly first until all orbitals of the same energy are filled
orbitals are filled such that the lowest energy state is maintained
what are the general rules of electron notation?
- fill the lowest energy orbitals first
- no two electrons can have the same quantum number - electrons have opposite spin
- opposing spin is filled before moving to the next orbital
what is the consequence of unpaired electrons in an orbital?
generation of magnetic field
how can the outer shell electrons be identified from the periodic table?
row or period number gives the ‘n’ of the element
what are the ‘s’ block elements and what does this mean?
first two columns of the periodic table and helium
the outer shell at ground state is a s sub shell - maximum of two electrons
what are the ‘p’ block elements and what does this mean?
13th to 18th columns of the periodic table
outer shell at ground state has a p sub shell - max 6 electrons
how many electrons can a d subshell have?
10
how many electrons can an f subshell have?
14
what are transition metals?
elements in columns 3 to 12 which have a partially filled d subshell
why do some transition metals form coloured solutions?
transition energies of the d subshell electrons
what is meant by ionisation energy?
the energy required to remove an electron from a gaseous atom or ion
what is meant by first ionisation energy?
energy required to remove one of the first outermost electrons from an atom in its gaseous state
what happens to first ionisation energy within a period/group?
increases from left to right (period)
decreases from top to bottom (group)
what is the second ionisation energy?
energy required to remove a second valence electron from an ion
what is electron affinity?
the ability of an atom to accept an electron. the stronger the attraction of a nucleus, the greater the electron affinity.
what is the general trend regarding electron affinity within the periodic table?
more negative left _> right across a period
what happens to the atomic radius across a period?
decreases from left to right - nuclear charge increases as the number of protons in an atom increases
increases moving down a group due to electron shielding
what is meant by electronegativity?
the ability of an atom to pull or repel an electron when engaged in a bond
the greater the electronegativity of an atom, the greater its attraction for bonding electrons
what determines bond strength?
bond strength is inversely proportional to bond length
what are the general characteristics of metals?
hard and shiny
3 or less valence electrons
form cations by losing electrons
good conductors of heat and electricity
what are the general characteristics of non metals?
gases, dull/brittle solids
5 or more valence electrons
form anions by gaining electrons
poor conductors of heat and electrons
what are the general characteristics of metalloids?
3-7 valence electrons
form pos or neg ions
conduct okay - not as good as metals
