The prefix eka- comes from the Sanskrit word for 'one.' Mendeleev used this prefix to indicate that the unknown element was one place away from the known element that followed the prefix. For example, eka-silicon, which we now call germanium, is one element below silicon. Mendeleev also predicted the existence of eka-manganese, which was not experimentally confirmed until 1937 because this element is radioactive and does not occur in nature. Based on the periodic table shown in Figure 7.1, what do we now call the element Mendeleev called eka-manganese?

Video transcript

Hey everyone in this example we're told that Mendeleev used the prefix E. K. A. To predict the existence of unknown elements. So E. K. A. Means one in Sanskrit and for example, he predicted the existence of germanium which is one element below silicon, which he named Eka Silicon. And based on this observation, we need to explain what the identity of the element that Mendeleev named kiki a aluminum when he formed the periodic table. So because we know that Eca silicon is an element that Mendeleev described as an element below silicon we would say, or according to the question that that element is germanium. So if we're given the term eca aluminum, we want to find the element below Aluminum on our periodic tables. And so when we look for aluminum on the periodic table, we see that it's located in group three a. And it has atomic number which we represent by the values e. Equal to 13. And so as we go down Group four A. Or group three A. Sorry beneath atomic number 13 we land on the atom G. A. Four gallium which falls at atomic number 31 also in Group three A. And so we can say that therefore eca aluminum describes the atom gallium. And so this would be our final answer to complete this example. So I hope that everything I explained was clear. If you have any questions please leave them down below and I will see everyone in the next practice video