The number of periods in the long form of the periodic table is
Nine
Eighteen
Seven
As many as groups
EKa- aluminium and EKa- Silicon are known as
Gallium and Germanium
Iron and Sulphur
Aluminium and Silicon
Fluorine and chlorine
Classification of elements in spiral form known as telluric helix was proposed by
Newlands
De- chancourtois
Mendeleev
Lother Meyer
Al3+ has lower ionic radius than Mg2+ because
Al3+ has higher nuclear charge than Mg2+
Mg has less number of neutrons than Al
Al has lower ionization potential the Mg atom.
Their electro negativities are different.
Diagonal relationship is shown by
f- block elements
elements of second period
d- block elements
elements of first period
The Van der Waal's radii of O, N, Cl, F and Ne increase in the order
N,O, F, Ne, Cl
Ne, F, O, N, Cl
F, O,N, Ne, Cl
Elements whose atoms have the general electronic configuration 4f 1-14 5s2 5p65d16s2 are referred to as
transition elements
lanthanoids
actinoids
representative elements
Screening power of electrons is in the order
f>d>p>s
s>p>d>f
s>p>f>d
The element Rutherfordium is a member of
Transition element
Inert gases
Alkali metals
Actinides