Answer: The chemical symbols for three different atoms or atomic cations with 27 electrons are [tex]Co,Cu^{2+} \& Ni^{1+}[/tex]
Explanation:
An atom is neutral specie with equal number of electrons and protons in it.
Atomic number = Number of protons = Number of electrons
Atomic number =- Number electrons = 27
The atom with 27 atomic number Cobalt that Co.
[tex][Co]=[Ar]3d^74s^2[/tex]
A cation is an ionic species which carry positive charge.When an atom looses an electron it forms cation.
Copper has atomic number of 29. When the copper atom looses 2 electrons it get converted into copper cation that is [tex]Cu^{2+}[/tex] with 27 electrons in its ion.
[tex][Cu]=[Ar]3d^{10}4s^1[/tex]
[tex][Cu^{2+}]=[Ar]3d^{9}4s^0[/tex]
Nickel has atomic number of 28.When the nickel atom looses 1 electron it get converted into nickel cation that is [tex]Ni^{1+}[/tex] with 27 electrons in its ion.
[tex][Ni]=[Ar]3d^{8}4s^2[/tex]
[tex][Ni^{1+}]=[Ar]3d^{8}4s^1[/tex]
So,the chemical symbols for three different atoms or atomic cations with 27 electrons are [tex]Co,Cu^{2+} \& Ni^{1+}[/tex]
