Question

1. which element would have the largest atomic radius? mark only one oval. li na k rb 18. which best explains why metals tend to form positive ions (cations)? mark only one oval. they have high electronegativity they lose valence electrons easily due to low ionization energy their nuclei are unstable they have more protons than neutrons 19. which element would most likely lose electrons and form a positive ion in a reaction? mark only one oval. oxygen magnesium neon chlorine 20. helium is chemically stable because... mark only one oval. it has one valence electron its outer shell is full it easily gains electrons it bonds strongly with other noble gases

Explanation:

17.

Step1: Recall atomic - radius trend

Atomic radius increases down a group in the periodic table. Li, Na, K, and Rb are in Group 1.

Step2: Identify the element with largest radius

Rb is the lowest in Group 1 among these elements, so it has the largest atomic radius.

Step1: Understand metal - ionization

Metals tend to form positive ions (cations) because they have low ionization energy and lose valence electrons easily.

Step1: Analyze electron - losing tendency

Metals lose electrons to form positive ions. Magnesium is a metal among the given options (Oxygen is a non - metal, Neon is a noble gas, Chlorine is a non - metal).

Step2: Confirm the answer

Magnesium has 2 valence electrons and will lose them to form a positive ion in a reaction.

Answer:

Rb

18.