Evaporation is simply molecules breaking into the air from a liquid. Molecules must achieve two things--'lifting' their weight, and interactions leaping with other molecules. In terms of size, smaller molecules should evaporate more quickly than bigger ones. With this in mind, ethanol molecules are larger than waters (see webpage above for observable oddities of water). Going on that ALONE, we would predict that of the two, ethanol should evaporate more slowly . However, this is not what is observed . Ethanol feels cooler on the skin and evaporates more quickly. We must look elsewhere for another factor! The secret lies in hydrogen interactions. water makes a ton of them; each of its atoms makes at least one. This creates a web of interactions holding each water molecule to several others-- and preventing evaporation. This is why water has an abnormally high boiling point for a small molecule. And it's related to the reason that unlike most solids, ice floats on its liquid (water). While we think of water as 'normal', it's actually a pretty outlandish liquid.

alkaline metals are lithium, sodium, rubidium, potassium, cesium and francium.

alkali metals have electronegativity from 0.7 to 1, lowest in periodic table of elements, which means that alkali metals (i group in periodic table) has positive oxidation number in compounds.

electronegativity is a chemical property that describes the tendency of an atom to attract a shared pair of electrons towards itself.

alkaline metals (far left in main group) have lowest ionizations energy and easy remove valence electrons,

for example, potassium is the alkali metal and has a single valence electron in the outer electron shell.

electron configuration of potassium is: ₁₉k 1s²2s²2p⁶3s²3p⁶4s¹.

they can not exist alone in nature, because they are very reactive.

the answer for sodium is 0.186

the answer for rubidium is 0.251

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

            and  

since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.