Final answer:
Elements with similar chemical properties are those in the same group on the periodic table, such as alkali metals. The correct answer to which elements have similar chemical properties is 'D: He, Ar, Kr', as they are all noble gases with full valence electron shells.
Step-by-step explanation:
The elements that have similar chemical properties are those that belong to the same group or family on the periodic table. The reason behind their similarity lies in the number of valence electrons they possess. For instance, alkali metals like lithium (Li), sodium (Na), and potassium (K) all have one valence electron, making them highly reactive and conferring similar chemical behaviors.
In the choices provided, Na (sodium) and K (potassium) are both alkali metals and hence have similar chemical properties, which includes being shiny, good conductors of heat and electricity, and forming compounds such as oxides in a 2:1 ratio with oxygen. Therefore, choice A: Na, K, Mg does not fit since Mg (magnesium) is an alkaline earth metal with two valence electrons. In the case of B: B, Al, Sc, these elements are not all in the same group: boron (B) is a metalloid, aluminum (Al) is a post-transition metal, and scandium (Sc) is a transition metal, and they do not all share the same number of valence electrons, thus their chemical properties differ. Similarly, choice C: N, O, F includes elements from different groups; nitrogen (N) is a nonmetal with five valence electrons, oxygen (O) is a chalcogen with six valence electrons, and fluorine (F) is a halogen with seven valence electrons. Lastly, D: He, Ar, Kr represents noble gases, which do share similar chemical properties due to having a full valence shell, making them very unreactive. Therefore, the correct answer for the question 'Which elements have similar chemical properties?' would be 'D: He, Ar, Kr'.