1. The Young's moduli of alkali metals are given below in units of GN m-1: Li (11.5), Na (9.0), K (3.5), Rb (2.7), Cs (1.8) and Fr (1.7). Compare this with the corresponding values of the melting points. Give a reason for this sequence.

1. 1. The Young's moduli of alkali metals are given below in units of GN m-1: Li
(11.5), Na (9.0), K (3.5), Rb (2.7), Cs (1.8) and Fr (1.7). Compare this with the
corresponding values of the melting points. Give a reason for this sequence.
Answer
Comparison of Young's moduli and melting temperature of the elements of
the given alkali metals are given below.
Element Atomic number Young's moduli
(Gpa)
melting
temperature (0
C)
Li 3 11.5 180.5
Na 11 9.0 97.8
K 19 3.5 63.38
Rb 37 2.7 39.31
Cs 55 1.8 28.44
Fr 87 1.7 27.14

2. The reason for this sequence it is evident that The Young's moduli scale with
melting temperature of the alkali metals .this is due to both The Young's
moduli and melting g temperature of any element (or even any material)
depends on the atomic compounds. That means strength of the bonds.
Strength of the bonds is related to that of bond order. Bond strength increases
with increasing bond order. The higher the bond order the stronger the bond.
In order to give the the sequence of alkali metals of the given data above let us
understand the basic things about alkali metal.
The alkali metals in the periodic it’s found in group 1A elements (Alkali Metals).
Alkali metals are lithium (Li), sodium (Na), potassium (K), Rubidium (Rb),
Caesium (Cs), Francium (Fr) and sometimes Hydrogen (H) is also included in the
group.
Except hydrogen all of the group elements are referred as alkali metals
because their oxides from strong alkies when dissolved in water.
All these elements are highly reactive.
Sodium and potassium do not occur in the Free State .they always occur in the
combined state. For example NaoH, Na2co3, K2Cr2O7.
Sodium and potassium are the most abundant of the alkali metals. They mostly
as their halides.

4. From the above graph the melting point of the alkali metals from lithium (Li) to
Francium (Fr) is decreasing when ones goes from top to bottom across the
group of elements.
That means Alkali metals are lithium (Li), sodium (Na), potassium (K), Rubidium
(Rb), Caesium (Cs), Francium (Fr).
As the atomic number is increasing the melting point and boiling point of alkali
metal is decreasing. In other words, the higher atomic number the lower the
boiling point and melting points. This is the main property of alkali metals ones
goes from the top to bottom across the group of alkali metals.
Increase in reactivity.
Increase in atomic radius.
Increase in electron shells shielding the outer electron.
Increase in ease of losing outer electrons to form a positive ion.
A tendency for the melting points and boiling points to decrease
Trend down group 1of the alkali metals.

5. Young's modulus is a mechanical property that is deals with the stiffness
of a solid material.
SI unit: pascal
In SI base units is denoted by Pa = kg m−1
s−2
For that of alkali metals the units are given by of GN m-1. Young's
modulus of alkali metals as the atomic number is increasing the melting
point, boiling point and Young's modulus of alkali metal is decreasing. In
other words, the higher atomic number the lower the boiling points, melting
points and Young's modulus based on the given data and characteristics
of alkali metal down the group in a periodic table.
The covalent nature of the bonding decrease as we go down any given
column of the periodic table .the elastic modulus show the
corresponding decrease.
Thank you!!!