Question

Use the periodic table in the tools bar to complete the electron configurations for the following elements:

Beryllium (Be): 1sC2sD

Answer 1

Johan Dobreiner

German Chemist that figured out that calcium, barium, and strontium have similar atomic masses and that strontium has an atomic mass half way between calcium and barium. Through this information he created various triads of elements based on one element having an atomic mass between two other elements and the three of those elements altogether having similar properties

John Newlands

English chemist that arranged all elements in terms of increasing atomic masses and that in every eighth element, there appeared to be a repetition of similar properties to the last eighth element (the law of octaves)

Dimitri Mendeleev

Russian chemist that, like Newlands, suggested that elements should be arranged in order of increasing atomic masses. However, unlike Newlands, he proposed that the law of octaves was not true and that periods of elements (horizontal rows on the periodic table) can vary in length (placed seven elements in first two, seventeen in the next two). He eventually made a periodic table that had eight columns (families) with blank spots in some places to eventually place elements that had not been discovered yet to validate the pattern he found(which he guessed their atomic masses and other properties very well). He concluded that an element's properties is a periodic function based on its atomic mass (the periodic law).