This video is of CBSE Class 10th X Science Chapter - Periodic Classification of Elements, on the topic "Dobereiner's Triads". Döbereiner’s Triads : In the year 1817, Johann Wolfgang Döbereiner, a German chemist, tried to arrange the elements with similar properties into groups. He identified some groups having three elements each. So he called these groups ‘triads’. Döbereiner showed that when the three elements in a triad were written in the order of increasing atomic masses; the atomic mass of the middle element was roughly the average of the atomic masses of the other two elements. For example, take the triad consisting of lithium (Li), sodium (Na) and potassium (K) with the respective atomic masses 6.9, 23.0 and 39.0. For more information please refer to below mentioned links : DronStudy official website : https://www.dronstudy.com Class 10 Science Video Lectures : https://www.youtube.com/playlist?list=PLKb9HOyS0VGTPNDNy9_R-akiSZGcerGlc Class 10 Science Full Course : https://www.dronstudy.com/shop/videos/class-x-science-2/ DronStudy Youtube Channel : https://www.youtube.com/channel/UCPiuJvuyMVFSwcIdBCTpTyQ For more information please contact us at : 8287971571