Question

What is the composition of the following alloys?
a. Brass
b. German Silver

Answer 1

Hint : There are 118 different elements known to us on this day. These elements are widely distributed in the earth’s crust in the free state as well as in the combined state. Based on their properties they are classified as metals, metalloids, non-metals, or inert gases. Of these known elements only 17 are non-metals.

Complete step by step solution :
Step 1
In every atom of an element, there is a positively charged nucleus and the negatively charged electrons revolving around it. So, the nucleus exerts an appreciable force of attraction on the planetary electrons. Thus, when we are removing an electron from the valence shell we will have to provide energy to overcome the attractive force of attraction which is exerted by the nucleus on the electrons.
Step 2
The amount of energy required to remove the most loosely bound electron from an isolated gaseous atom to form a gaseous ion is called the ionization enthalpy of ionization energy. The voltage at which the ionization of gas occurs is known as the ionization potential and is numerically equal to the ionization energy of the gas expressed in eV.
Step 3
The factors on which the ionization energy depends:
Size of the atom – Ionization energy decreases with an increase in atomic size. So, the smallest atom has the highest ionization energy.
Nuclear charge – Ionization energy increases with an increase in nuclear charge provided the valence shell remains the same.
Screening effect – if other factors remain the same ionization energy decreases with the increase in the number of inner electrons.
Step 4
The respective position of the given elements in the periodic table:
K – 4th period, group 1
Na – 3rd period, group 1
Be – 2nd period, group 2
Mg – 3rd period, group 2
Hence, the Be has the least atomic size and thereby the maximum ionization potential, and the correct answer for the given question is option c).

Note : The unit of Ionization enthalpy is $kJ/mol$and ionization potential is $eV/mol$.
$1eV = 1.6021 \times {10^{ - 19}}J = 1.6021 \times {10^{ - 22}}kJ$