Anew element -- quickly named swiforskium by the scientific community -- is discovered. this element is found to have two isotopes. 86.4% of all swidorskium atoms are swidorskium-428 and 13.6% are swidorskium-433. what is the atomic mass of this element? show your work.

The average  atomic mass of this element is 428.68 .

Explanation:

Average atomic mass =

Atomic mass of Swidorskium-428 = 428

Abundance of Swidorskium-428 = 86.4%=0.864

Atomic mass of Swidorskium-433. = 433

Abundance of Swidorskium-433 = 13.6= 0.136

The atomic mass of the element is

= (atomic mass of Swidorskium-428 )(abundance) + (atomic mass of Swidorskium-433)(abundance)

The atomic mass of Swidorskium = (428)(0.864)+(433)(0.136) = 428.68

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.