To understand how magnesium and chlorine combine to form magnesium chloride (MgCl2), we can use Lewis dot diagrams to visualize the electron transfer between these elements.
Magnesium (Mg) is in Group 2 of the periodic table and has two valence electrons. Its Lewis dot diagram can be represented as:
Mg: ••
Chlorine (Cl), on the other hand, is in Group 17 and has seven valence electrons. Its Lewis dot diagram is shown as:
Cl: •••••• •
When magnesium and chlorine react, magnesium tends to lose its two valence electrons to achieve a stable electron configuration similar to the noble gas neon. This loss turns magnesium into a cation:
Mg → Mg2+ + 2e-
On the other hand, each chlorine atom needs one more electron to complete its octet. In the reaction, one magnesium atom donates its two electrons, one to each of two chlorine atoms:
Cl: •••••• • + e- → Cl: •••••• • • Cl: •••••• • + e- → Cl: •••••• • •
As a result, after gaining one electron each, the two chlorine atoms become anions:
Cl → Cl- Cl → Cl-
Now, magnesium, which is positively charged, and the two negatively charged chlorine atoms combine to form the ionic compound magnesium chloride:
Mg2+ + 2Cl- → MgCl2
In summary, the reaction involves the transfer of electrons from magnesium to chlorine, resulting in the formation of ions and the creation of magnesium chloride.