Question

question 38 (1 point)
which of the following elements has the smallest ionic radius?
o a s
o b li
o c o
o d k

question 39 (1 point)
what is the energy required to remove an electron from an atom in the gaseous state called?
o a shielding energy
o b ionization energy
o c nuclear energy
o d electronegative energy

question 40 (1 point)
by the early 1800s, chemists started organizing elements into groups because
o a the printing press made it possible to disseminate knowledge faster.
o b more books were being published on the topic.
o c there were so many new elements that had been discovered.
o d universities had a sudden influx of students interested in chemistry.

Explanation:

Question 38

Ionic radius trends: In general, as you move up a group in the periodic table, ionic radius decreases. Also, for ions with the same charge, smaller atoms (higher in the group) have smaller ionic radii. Among the given elements, oxygen (O) is higher up in its group compared to sulfur (S). Lithium (Li) forms \(Li^+\) (lithium ion), oxygen forms \(O^{2 -}\), sulfur forms \(S^{2 -}\), and potassium forms \(K^+\). Comparing \(Li^+\) (\(76\) pm), \(O^{2 -}\) (\(140\) pm), \(S^{2 -}\) (\(184\) pm), \(K^+\) (\(138\) pm) (approximate values). \(Li^+\) has a smaller ionic radius than \(K^+\) (as Li is in period 2 and K in period 4). But when considering the charge - size ratio and electron - electron repulsions in anions (\(O^{2 -}\) and \(S^{2 -}\)) and cations (\(Li^+\) and \(K^+\)), \(Li^+\) has a relatively small ionic radius.

Ionization energy is defined as the energy required to remove an electron from an atom in the gaseous state. Shielding energy is related to the reduction of the effective nuclear charge due to inner - shell electrons. Nuclear energy is related to energy changes in the nucleus (e.g., fission, fusion). Electronegative energy is not a standard term in this context. The key definition here is for ionization energy.

By the early 1800s, many new elements were discovered. Chemists needed a way to organize these elements to understand their properties, reactivity, etc. The printing press (option a) and more books (option b) are more about knowledge dissemination, not the driving force for organizing elements. The influx of students (option d) is not the main reason for organizing elements. The large number of new elements (option c) made organization necessary.

Answer:

b. Li

Question 39