Calculate the wave length of an electron moving with a velocity of 2.08*10^7 ms^-1

indium, and thallium have three electrons i think

metric time was an attempt to create a standard unit of time based off of 10, but it never took off an is not included in the metric system (si)

answer///carbon;

answer: atomic mass was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version.

explanation:

originally atomic mass was used to arrange elements on the periodic table from left to right in a row. each column then shows similar properties of elements of a group.

in modern periodic table, the atoms are arranged in increasing atomic number. as atomic number represents the number of protons in an atom which is unique for every atom.