periodic table Flashcards
(23 cards)
what is dobreiner triads
dobreiner arranged elements in increasing order of atomic weights in group of three called triads where the middle one is the average mean of the other wo elements
what were the limitation of dobreiner
it was not true for all elememts
nd the properties were no similiar
what were the newlamd law of octaves
he set the elements in increasing order of atomic weights in series of eight where the first and the eighth element showed similarity in properties
limitations of newland
odd grouping
didnot leave space for undiscovered elements
what were mendeleeff
he arranged elements in increasing order of atomic weights in 7 periods and 18 groups
name three periodic properties
atomic radius ionization potential electron affinity
name any three contributions mendeelleff gave
he left spaces for undiscovered elements
elements is same group had same valency
they were arranged in increasing order of atomic weights in 7 periods and 18 groups
state the limitations of mendeellef
isotopes
actinide and lactinide
anomoulus behaivour more atomic weoght before the less atomic weight
moseley classification
he arranged elememts in increasing order of atomic numbers in 7 periods and 18 groups and this was callled modern periodic table
what is periodicity in properties
the physical and chemical properties of an element is the periodic function of their atomic number hence when elements are placed in increasing order of atomic number they showed similarity in properties after regular intervals this is called periodicity in properties
why is there periodicity in properties
after regular interval there is recurrence of electronic confihguration
def atomic radius
the distance between the centre of the nucleus to the outermost shell is called atomic radius
def ioniztion potential
the amount of energy required to remove an atom from outermost shell of isolated aom
def electron affinity
the amount of energy released when an atom in the gaseous state accepts an electron to fprm anion
property trends in period
elecronic shells is same
valence electrons increases by one and tranisition of mettalic to nonmetallic character
property trends in a group
valence electrons is same
electron shell increases by one
state some properties of alkali metals group 1
they are electropositive giid conductor of heat are soft can be cut woth knife strong reducing agents
state some properties of halogens
electronegative non conductors of heat strong oxidising agents
what are bridge elements
the element is second group show similarity in properties woth third group leading to diagonal relationship which is called bridge elements eg- li and magnesium
most reactive halogen and most abundant halogen is?
most reactive fluorine most abundant chlorine
what is allotropy
abilty of an element to exist in more than one form they have same graded chemical properties but diffent physical properties
what is electronegativity
tendency of an atom to attract electrons to itself
