periodic classification Flashcards
no of elements in 1800
31
no of elements in 1865
63
current no of elements
118
dobereiner’s triad examples
Li, Na, K
Cl, Br, I
Ca, Sr, Ba
newland octave was applicable only till
calcium - 40
Lothar Meyers curve is based on
atomic volume vs atomic weight
in Lothar Meyers curve the group 1A metals occupied
top point of each curve
in Lothar Meyers curve
group 2A
mid points on descending curve
in Lothar Meyers curve most electronegative halogens occupied
the ascending portions of the curve
mendels periodic law is based on
atomic weight or atomic mass
how many groups and periods
9 and 7
who observed characteristic X ray spectra of the elements
Hendry Moseley he proved that the elements must be placed based on their atomic number
no of groups and periods in modern periodic table
18 and 7
group 17 are called as
halogens
group 16 are called as
chalcogens
