Periodic Trends Quiz: Reactivity, Radius & Ionization Energy

Krypton is the correct answer for the element in Group 18, Period 4. Krypton is a noble gas and belongs to the Group 18 elements, also known as the noble gases. It is symbolized by Kr on the periodic table. Noble gases are known for their low reactivity and full outer electron shells, making them stable and nonreactive. Krypton is used in various applications, such as in fluorescent lights, lasers, and as a filling gas in certain types of insulation.

Boron and Silicon are both metalloids that are in the first 20 elements. Boron has the symbol B and Silicon has the symbol Si.

The elements located in Group 2 of the periodic table are called alkali earth metals. These elements include beryllium, magnesium, calcium, strontium, barium, and radium. They are called alkali earth metals because they are found in the earth's crust and have similar properties to the alkali metals found in Group 1. They are shiny, silvery-white metals that are relatively soft and reactive. The "the" before alkali earth metals in the answer is incorrect, as it is not necessary to use "the" when referring to this group of elements.

The given electron configuration, 2,8,8,1,2,8,8,1, represents the electron arrangement of two elements in Group 1, Period 4. The first element has an electron configuration of 2,8,8,1, which corresponds to potassium (K), while the second element has an electron configuration of 2,8,8,1, which corresponds to rubidium (Rb). Both potassium and rubidium have one valence electron in their outermost energy level, making them highly reactive alkali metals.

Chlorine and iodine are both elements that belong to the Halogens group (Group 17/Group 7). They exhibit similar chemical properties as other elements in this group, such as high reactivity and the ability to form salts with metals. Sulphur, oxygen, nitrogen, boron, and carbon do not belong to the Halogens group and have different chemical properties. Therefore, the correct answer is chlorine and iodine.

Cesium is the most reactive metal because it is located at the bottom left corner of the periodic table, which means it has the lowest ionization energy and is more likely to lose electrons and form positive ions. On the other hand, Mercury is the least reactive metal because it is a transition metal and is located towards the middle of the periodic table. Transition metals tend to have higher ionization energies and are less likely to form positive ions.

Chlorine is the most reactive nonmetal because it is highly electronegative and readily accepts an electron to achieve a stable electron configuration. On the other hand, iodine is the least reactive nonmetal because it has a larger atomic radius and is less likely to gain or lose electrons.

Bromine is the correct answer because it is the only liquid element on the Periodic table at room temperature. Mercury is a liquid at room temperature, but it is not considered an element on the Periodic table. Chlorine and Argon are both gases at room temperature.

Fluorine is the most reactive nonmetal. It has 2 electron shells. The electron shell configuration of fluorine is 2,7. It is in group 7 and period 2.