Complete question is;
Chemical reactivity of alkali metals increases down the group while reactivity of halogens decreases down the group. Give reasons
Answer:
Explained below
Explanation:
Alkali metals exhibit reactivity due to their electropositivity. Now, for alkalis, their electro-positivity increases down their group. Since their reactivity increases with increase in electropositivity, it means their reactivity also increases down the group.
Whereas, the reactivity of halogens occurs as a result of their electronegativity. Now, electronegativity for halogens decreases down the group. Since their reactivity decreases with decrease in electronegativity, it means that their reactivity will also decrease down the group.
<u>Answer:</u> The electronic configuration of gallium is written below and number of valence electrons is 3.
<u>Explanation:</u>
Electronic configuration is defined as the representation of electrons around the nucleus of an atom.
Number of electrons in an atom is determined by the atomic number of that atom.
Valence electrons are defined as the electrons present in the outermost shell of an atom.
We are given:
An element Gallium having atomic number as 31.
Number of electrons = 31
Electronic configuration of Gallium is: 
This element has 3 electrons in its outermost shell. So, the number of valence electrons is 3
Hence, the electronic configuration of gallium is written below and number of valence electrons is 3.
Answer:
Molecular solid
Explanation:
A molecular solid has a low melting point, they are soft and do not conduct electricity.
We have been told in the question that the solid does not really dissolve in water and it's solution does not improve the electrical conductivity of water. Hence, it must be a molecular solid.
Answer:
Americium is: [Rn]5f^7s^2
Bismuth is: [Xe]6s^24f^145d^106p^3
Tin is: [Kr]4d^105s^25p^2
Vanadium is: [Ar]3d^34s^2
Aluminum is [Ne]3s^23p^1
