Why potassium is lighter than sodium in density?

Basically, as you go down a group the elements are heavier because they contain more protons and neutrons in their nuclei. Lithium has lesser atomic weight than sodium.So, lithium has lesser density than sodium. Thereby density of ‘K’ decreases. So Potassium has a lower density than Sodium.

Why does the density of metals increase down the group?

As we down in a group then its size increases and also volume of the atom increases as the number of electrons and protons increases. But if increase in volume is greater than that of increase in mass then density will decrease in that case. So, on moving top to down in a group, the atomic density generally increases.

Are lithium sodium and potassium are denser than water?

lithium, sodium and potassium are less dense than water so they float on the surface of the water.

Why does density increase from lithium to Caesium?

Basically, as you go down a group the elements are heavier because they contain more protons and neutrons in their nuclei. But working against this is the fact that the increased nuclear charge tends to pull all the electrons closer, resulting in a smaller atomic radius and hence a higher density.

What is the density of lithium?

0.534 g/cc
Density of Elements Chart

Density	Name	Symbol
9.73 g/L	Radon	Rn
0.534 g/cc	Lithium	Li
0.862 g/cc	Potassium	K
0.971 g/cc	Sodium	Na

Does potassium have a high density?

Density down a group generally increases, with the notable exception of potassium being less dense than sodium. Basically, in the case of sodium and potassium the increase in shell size outweighs the pull of the core on the outer shell electron and so potassium is less dense than sodium.

Is potassium more dense than lithium?

Larger the size larger is the density because there is large increase in mass with considerable increases in volume. Hence density increases down a group as size increase down the group. The metals in this series are relatively light—​lithium, sodium, and potassium are less dense than water (less than 1 g cm-3).

Does lithium has a lower melting point than potassium?

The alkali metals also have low densities . They are low enough for the first three (lithium, sodium and potassium) to float on water….Example.

Element	Melting point
Lithium, Li	180°C
Sodium, Na	98°C
Potassium, K	63°C
Rubidium, Rb	39°C

Why does reactivity decrease down Group 4?

Ions are much smaller than atoms because they have lost the outer energy level and the nuclear charge is attracting four fewer electrons. Ionisation energies decrease down the group as the outer electrons become further from the nucleus and more highly shielded from the inner shells.

Why does potassium have a lower density than sodium?

Though there is a trend in increasing density down the groups in the periodic table, there is an exception in the density trend between sodium and potassium. The exception is that although the atomic mass increases and the number of protons increase for potassium, its density is less than that for sodium.

Why does the density of K increase in alkali metals?

In alkali metals, atomic weight increases down the group. Lithium has less atomic weight than Sodium. So density of ‘Na’ is greater than that of ‘Li’. But in the case of ‘K’ and ‘Na’, d-orbitals present in Potassium, which increases the volume of ‘K’. Thereby density of ‘K’ decreases.

Why is pottasium lighter than sodium?

Pottasium is lighter than sodium because there is an unusual increase in atomic size i. e., atomic volume of pottasium. This happens because of the addition of empty 3d orbitals.

How does density change down the group of metals?

Hence density increases down a group as size increase down the group. The metals in this series are relatively light—​lithium, sodium, and potassium are less dense than water (less than 1 g cm-3). It is difficult to develop a simple explanation for this trend because density depends on two factors, both of which change down the group.