Question

Mendeleev predicted the existence of certain elements not known at that time and named two of them as eka-aluminium, and eka-silicon.
(a) Name the element which has taken the place of (i)eka-aluminium, and (ii)eka-silicon
(b) Mention the period/periods of these elements in the modern periodic table.
(c) Write the group/groups of these elements in the modern periodic table.
(d) Classify these elements as metals, non-metals or metalloids.
(e) How many valence electrons are present in the atoms of each of these elements ?

Lakhmir Singh Chemistry Class 10

Answer 1

Answer:

in modern periodic table have 4 blocks fist s nd p nd p last grop element hv ful electron in these elements

Answer 2

Answer:

a) eka aluminium is Gallium and eka-sillicon is Germanium.

b) Both are in 4th period.

c) Gallium is in 13th group and germanium is in 14th group.

d) Gallium is metal and Germanium is a metalloid.

e) Gallium has 3 and Germanium has 4 valence electrons .