A generic element, Z, has two isotopes, 45Z and 47Z, and an average atomic mass of 45.36 amu. The natural abundances of the two isotopes are 80% 45Z and 20% 47Z. The isotopic mass of 45Z is 44.96 amu. What is the isotopic mass of 47Z?

46.96 amu

Explanation:

Isotopes are different kinds of same elements. The difference between two isotopes of the same element is the number of neutrons.

To get the relative atomic mass, we take into consideration the masses of the different isotopes. This is done by multiplying their abundances by their masses. They are then added together to get the relative atomic mass of the element.

Let the isotopic mass of 47Z be x

45.36 = [80/100 * 44.96] + [20/100 * x]

45.36 = 35.968 + 0.2x

0.2x = 45.36 - 35.968

0.2x = 9.392

x =9.392/0.2 = 46.96 amu

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.