Why did you need two or more clues to place other elements? Explain using examples.

The study of chemicals is called chemistry.

The answer is mentioned below.

A new element is placed in a periodic table according to the number of electrons present in the atoms or we can say that the new element is placed according to the atomic number.

Hence, these are the following by which a new element is placed in the table,

Hence, the correct answer is atomic number and its mass.

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Two or more clues are required to place elements in the periodic table because different elements have some similar properties.

For example: If it is required to place Chlorine in the periodic table. Its property such as it is a nonmetals is not enough to place it in the periodic table as there are many other nonmetals. So, some more information such as its atomic number is 17 and belongs to 17 group would help more.

first, consult an activity series chart to determine if al is more reactive than fe. it is, so it will replace the fe. now, one can continue with the problem.

next, make sure you have a correctly balanced equation.

3feo + 2al ==> 3fe + al2o3

now, determine which reactant (feo or al) is in limiting supply.

moles feo present = 125 g x 1 mole/71.8 g = 1.74 moles

moles al present = 25.0 g x 1 mole/26.98 g = 0.927 moles

since from the balanced equation, it take 3 mol feo for every 2 mol al, al will be limiting.

you can determine this simply by dividing moles of each by their coefficient in the balanced equation. for example: 1.74/3 = 0.58 and 0.927/2 = 0.464. al is less, so it is limiting.

finally, using the stoichiometry in the balanced eq. determine mass of fe that can be produced from 0.927 moles of al.

0.927 moles al x 3 moles fe/2 moles al x 55.8 g/mole = 77.6 g

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