Identify each of the following elements: a. a member of the same family as oxygen whose most stable ion contains 54 electrons b. a member of the alkali metal family whose most stable ion contains 36 electrons c. a noble gas with 18 protons in the nucleus d. a halogen with 85 protons and 85 electrons

To identify the element, we need to look at the same family as oxygen, which is the chalcogen family (Group 16). The most stable ion of this element contains 54 electrons. Oxygen has 8 electrons, so let's find the number of protons in this element. This element has 2 more electrons for its most stable ion, which means it has 56 protons. Using the periodic table, we can identify the element with 56 protons, which is Barium (Ba). However, Barium belongs to Group 2, not Group 16. This discrepancy shows that the element must have lost 2 electrons instead of gaining 2 electrons. So, the element we are looking for has 2 fewer protons than Barium, which means it has 54 protons. Using the periodic table again, the element with 54 protons is Xenon (Xe) which is in Group 18, not Group 16. This means that the element has gained 2 electrons rather than lost 2 electrons. So our final answer is Tellurium (Te) with 52 protons, as it belongs to Group 16.

We are looking for a member of the alkali metal family (Group 1) whose most stable ion contains 36 electrons. Alkali metals have 1 electron in their outermost shell, and they lose that electron to form a positive ion. Since the most stable ion has 36 electrons, the original atom must have had 37 electrons (since it loses one to form the ion). Using the periodic table, the element with 37 electrons and protons is Rubidium (Rb).

Using the periodic table, we look for a noble gas with 18 protons in its nucleus. Noble gases belong to Group 18. The element with 18 protons is Argon (Ar), which is in Group 18 (noble gases family).

We are looking for a halogen with 85 protons and 85 electrons. Halogens belong to Group 17. Using the periodic table, we find the element with 85 protons is Astatine (At), which is in Group 17 (halogens family).