Why do the elements of period 4 start a new cycle of properties after the element argon? select all that apply. - the electrons in the outermost energy level are primarily responsible for the properties of an element. -the n = 3 energy level of argon is complete. - additional electrons after argon begin to fill a sublevel of the n = 4 energy level. - all the energy levels of period 4 elements are less than period 3 because the amount of energy between energy levels decrease with distance from the nucleus.

The correct statements are the electrons in the outermost energy level are primarily responsible for the properties of an element and additional electrons after argon begin to fill a sub level of the n = 4 energy level.

Explanation:

Valence electrons are defined as the electrons which are present in the outermost shell of an element. It determines the chemical properties for an element.

The elements having same number of valence electrons show similar chemical properties and thus are groups in same Group.

Reactivity is defined as the tendency for an element to gain and loose electrons. This is determined by the number of valence electrons in an element.

Thus, the correct statements are the electrons in the outermost energy level are primarily responsible for the properties of an element and additional electrons after argon begin to fill a sub level of the n = 4 energy level.