Question

1. metals lose electrons to form positive ions. the charge on the group 1 metal ions is +1 because they have lost one electron. the group 2 metal ions have a charge of +2, and the group 3 metal ions have a charge of +3. 2. non - metals gain electrons to form negative ions. the charge on the group 17 non - metal ions is -1 because they have gained one electron. the group 16 non - metal ions have a charge of -2, and the group 15 non - metal ions have a charge of -3. learning check 1. helium, like other noble gases, has a full, and therefore stable, outermost electron shell structure. how many electrons are in heliums outermost shell? what about the other noble gas elements? why is there a difference? 2. how can metal elements achieve a stable electron - shell structure like those of the noble gases?

Explanation:

Step1: Identify electron - shell structure of helium

Helium has only one electron shell (the K - shell), and the maximum number of electrons in the K - shell is 2. So, helium has 2 electrons in its outermost (and only) shell.

Step2: Identify electron - shell structure of other noble gases

Other noble gases (Ne, Ar, Kr, Xe, Rn) have more than one electron shell. The outermost shell of these noble gases has 8 electrons, which is a stable octet configuration.

Step3: Explain the difference

Helium has only one electron shell, and the first shell can hold a maximum of 2 electrons. For other noble gases, they have multiple electron shells, and the outermost shell is most stable with 8 electrons according to the octet rule.

Step4: Answer how metal elements achieve stable structure

Metal elements have a small number of valence electrons. They achieve a stable electron - shell structure like noble gases by losing their valence electrons. For example, Group 1 metals lose 1 electron, Group 2 metals lose 2 electrons, and Group 3 metals lose 3 electrons to attain a stable electron configuration similar to that of the previous noble gas.

Answer:

1. Helium has 2 electrons in its outermost shell. Other noble gas elements have 8 electrons in their outermost shell. The difference is due to helium having only one electron shell (which is full with 2 electrons), while other noble gases have multiple electron shells and follow the octet rule (8 electrons in the outermost shell for stability).
2. Metal elements achieve a stable electron - shell structure like those of the noble gases by losing their valence electrons.