Question

Question #728e3

Answer 1

Alkali earth metals have a valance configuration of `s^2`
Halogens have a valance configuration of `s^2p^5`
Both families of elements are chemically active.

Explanation:

Alkali Earth metals with a valance configuration of `s^2` can most easily become stable by sharing these valance electrons with an element that is electrophilic. This leaves the Alkali Earth metals with the outside valance electron structure of a noble gas of the next lower electron shell.

Halogens with a valance configuration of `s^2p^5` can most easily become stable by acquiring an electron from another element. This leaves the Halogens with the outside valance electron structure of a noble gas in the same period.

Both of these families of elements are very active chemically.

Answer 2

Here's what I get.

Explanation:

`bb("Alkaline Earth"color(white)(ml)"Halogen")`
`"Be"color(white)(m)["He"] "2s"^2color(white)(mmmm)"F"color(white)(m)["He"] "2s"^2 "2p"^5`
`"Mg"color(white)(ll)["Ne"] "3s"^2color(white)(m)color(white)(mmm)"Cl"color(white)(ll)["Ne"] "3s"^2 "3p"^5`

`"Ca"color(white)(m)["Ar"] "4s"^2color(white)(m)color(white)(mmm)"Br"color(white)(ll)["Ar"]"4s"^2 "3d"^10 "4p"^5`
`"Sr"color(white)(ml)["Kr"] "5s"^2color(white)(m)color(white)(mmm)"I"color(white)(ml)["Kr"] "5s"^2 "4d"^10 "5p"^5`

`"Ba"color(white)(m)["Xe"] "6s"^2color(white)(m)color(white)(mmm)"At"color(white)(ll)["Xe"]"6s"^2 "4f"^14 "5d"^10 "6p"^5`
`"Ra"color(white)(m)["Rn"] "7s"^2color(white)(m)color(white)(mmll)"Ts"color(white)(m)["Rn"] "7s"^2 "5f"^14 "6d"^10 "7p"^5`

The alkaline earth metals have a electron configuration ending in `n"s"^2`.

They can get a noble gas configuration by losing their two `"s"` electrons.

The halogens have an electron configuration ending in `n"s"^2 n"p"^5`.

They can get a noble gas configuration by gaining one electron to complete their octet.

Thus, an alkali metal `"M"` will react by donating an electron to each of two halogen `"X"` atoms.

The metal will become a metal cation `"M"^"2+"` and the halogen will become an anion `"X"^"-"`.

`"M + 2X" → "M"^"2+", "2X"^"-"`