What is the relationship between melting points and boiling points of alkali metals?

Answer 1

From BCIT.ca: The alkali metals show a decrease in melting points and boiling points due to the weaker metallic bonds between atoms as their size increase down the group.
From AUS-e-TUTE: melting point decreases down the Group as the elements become less metallic in nature
From okstate.edu: As one goes down the Periodic Table, the metallic radius of alkali metals increases. The increase in radius results in much decreased attractive forces between atoms within the liquid metals, resulting in a decrease in heat of vaporization and boiling points [and melting points] because less heat is needed to separate atoms from the liquid [or solid] state within the larger alkali metals. See Web Links to the left for the original sources.

Answer 2

The Bohr model, introduced in 1913 by Niels Bohr was simply the model of the atomic structure; this included the small positively charged nucleus which included the neutrons and protons at the centre and the negatively charged electrons rotating around the nucleus in certain specific orbits by its electromagnetic energy in a circular orbit, similar to the solar system, but with electrostatic forces providing attraction, rather then gravity. In a neutral atom the number of electrons = the number of protons. The arrangement of an atom's energy orbits depends on the number of protons and neutrons in the nucleus and the number of electrons orbiting the nucleus.

Answer 3

The relationship of the alkali metals is simple, as the atomic radius increases the inter molecular forces become weaker as there is less gravitational force acting on the electrons as they are further away from the nucleus (source of gravity), making it easier for them to react/come loose. This is why the melting and boiling points decrease.