Final answer:
To determine the electron configuration of ions, we look at the electron configuration of the neutral atom and add or remove electrons corresponding to the ion's charge. For instance, O²- has the electron configuration 1s²2s²2p¶, while Ca²+ has 1s²2s²2p¶3s²3p¶.
Step-by-step explanation:
To write the electron configuration for ions, we first need to know the electron configuration of the neutral atom and then adjust it by adding or removing electrons based on the charge of the ion. Neutral atoms fill their electron shells in order of increasing energy level and subshell.
O²-: The oxygen atom normally has 8 electrons. As an O²- ion, it gains 2 more electrons. Hence, the electron configuration for O²- is 1s²2s²2p¶.
Ca²+: Calcium normally has 20 electrons. As a Ca²+ ion, it loses 2 electrons. The electron configuration for Ca²+ is 1s²2s²2p¶3s²3p¶.
N³-: The nitrogen atom normally has 7 electrons. As an N³- ion, it gains 3 electrons. The electron configuration for N³- is 1s²2s²2p¶. K+: Potassium normally has 19 electrons. As a K+ ion, it loses 1 electron. The electron configuration for K+ is 1s²2s²2p¶3s²3p¶.