Question

In byju app the video on s block elements, sir in the video on physical properties of 1 group element at 1:03 min sir said Li exist in HCP shape but at 3:45 min in same video he said it is the only one who does not exist in HCP structure!!!! Why????

Answer 1

The crystal structure of lithium is Body Centred cubic (bcc). The other alkali metals like sodium and potassium is also existing as body centre cubic. However the beauty is the energy difference between bcc and hcp for this elements are quite low. So they will change the structure in low temperatures. So we can generally say that alkali metals have general crystal structure as bcc for top elements with exceptions at lower temperature.