A an excellent place to start as soon as trying to figure out the electron construction of an *ion* is the electron configuration of the **neutral** parental atom.

In this case, *titanium*, #"Ti"#, is located in duration 4, group 4 the the regular table and has an atomic variety of #22#.

This way that a **neutral** titanium atom will contain #22# proton in that is nucleus and #22# **electrons** bordering its nucleus.

Therefore, the electron configuration of a neutral titanium atom must account because that #22# electrons. Consequently, the electron configuration of the titanium(II) cation, #"Ti"^(2+)#, must account because that #20# **electrons**, because this cation is created when a neutral titanium atom **loses** #2# electrons.

The electron construction of a neutral titanium atom looks choose this

#"Ti: " 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^2#

Now, it"s necessary to keep in mind that this notation because that the electron construction is advantageous when **adding electrons** to construct an atom "from scratch" since in the case, the #4s# **orbital** is to fill **before** the #3d# **orbitals**.

That happens because the *empty* #3d# **orbitals** room actually *higher* in power than the *empty* #4s# **orbital**, as checked out here

However, when the #4s# orbit is **filled**, it i do not care *higher* in power than the #3d# orbitals.

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This way that as soon as titanium **loses electrons**, it does therefore from the #4s# **orbital** *first*.

#"Ti: " 1s^2 2s^2 2p^6 3s^2 3p^6 3d^2 4s^2#

Therefore, the 2 electrons the are lost when the #"Ti"^(2+)# is developed will come native the #4s# orbital, which means that the electron configuration of the cation is

#color(green)(|bar(ul(color(white)(a/a)color(black)("Ti"^(2+): 1s^2 2s^2 2p^6 3s^2 3p^6 3d^2)color(white)(a/a)|)))#

If you want, you deserve to use the **noble gas shorthand notation** come write

#color(green)(|bar(ul(color(white)(a/a)color(black)("Ti"^(2+): <"Ar"> 3d^2)color(white)(a/a)|)))#

Here #<"Ar"># to represent the electron construction of argon, the noble gas that comes instantly **before** titanium in the routine table.