Using principles of atomic structure, explain why the atomic radius of Te is less than the ionic radius of Te2− . Photoelectron spectroscopy data for the 1s sublevel of Te and the 1s sublevel of O are represented below. In terms of Coulomb's law and atomic structure, explain why the peak for O is positioned so far to the right of the peak for Te .

Using principles of atomic structure, the reason why the atomic radius of Te is less than the ionic radius of Te²− is because of the Electrostatic force of repulsion between the negatively charged electrons of Te²- thereby causing the ion to be bigger than the neutral atom.

By considering the second scenario, the element oxygen is positioned so far on the right because it has a very much smaller nuclear charge compared to Te.

As a result, in the PES spectrum, the 1s sublevel of oxygen lies far to the right of the 1s sublevel of Te.

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Explanation:

Let us recall that a negative ion is formed by addition of electrons to an atom. When electrons are added to the atom, greater interelectronic repulsion increases the size of the Te^2− hence it is greater in size than Te atom. Therefore, the ionic radius of Te^2− is greater than the atomic radius of Te.

In the second question, oxygen is positioned so far to the right because it has a far smaller nuclear charge compared to Te. Hence in the PES spectrum, the 1s sublevel of oxygen lies far to the right of that of Te.

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.