Question

Why do gallium and cesium melt in our palm?

Answer 1

Hint: To answer this question the periodic properties of the elements from different groups should be known. The periodic properties have opposite trends between left to right and top to bottom. Gallium is from group 13 and cesium is from the group 1 of the periodic table.

Complete step by step answer:
The elements in periodic tables are arranged in a way that every element of each group shows similar physical characteristics and chemical characteristics. But due to some opposite trends of periodic properties from left right and top bottom, there are some similarities observed between two different group elements.
At the temperature when a solid substance melts and is converted into liquid is called the melting point of that substance.
Now, in case of gallium and cesium due to high effective nuclear charge their nature is electropositive, which makes the bond between gallium atoms weaker. Due to the weaker bond of gallium atoms their melting point is also low.
Due to the low melting point of gallium and cesium they let in our palm with the temperature of the body.

Note: In the periodic table all the elements are arranged by the atomic numbers. Generally, at the left side of the periodic table, elements are metallic in nature. Moving from left to right the metallic character decreases and non-metallic character increases. At the extreme left elements are non-metallic in nature. There are a total 118 number of the elements in the modern periodic table.