Magnesium is an alkali earth metal, found in group two (S - Block) of the periodic table, it forms 2+ ions, and is quite reactive, upon heating it will burn with a brilliant white glow.
Hydrogen Chloride is an acid gas, or when dissolved in water, it forms an aqueous solution known as hydrochloric acid, any hydrogen halide is acidic, with acidity increasing going down the group, the halides are the non-metals in group 7 (P- Block).
Magnesium, or Mg, has two electrons in its outer shell, and obeying the octet rule, that states during bonding an atom will try to gain 8 outer shell electrons, it’s clear to see, for Mg it would much easier to lose 2 electrons, than gain 6. So upon losing 2 electrons, the Mg atom, becomes a 2+ ion, (a Charged Atom with a 2 positive charge)
HCL in aqueous solution is a solution of H+ ions and CL- ions. We can ignore the H+ ions at this stage; the Cl- ions are what react with the Mg, to form magnesium chloride.
This happens due to electrostatic forces of attraction, e.g. +ve attracts –ve,
So we know now that the negative chlorine ion, is attracted to the positive Mg ion, and these two Ionic bond, but the magnesium has a 2 positive charge, and compounds generally don’t like being charged, so, the magnesium attracts two chloride ions,
Mg2+ + 2Cl- = MgCl2
This has taken care of two of the ions, but now, where did the electrons go?
Well the H+ ion attracts them, to form H2 gas
H+ + 2e- = H2
So no substance is left charged, and no electrons escaped the system.
The Ionic bond is when ions are formed, and attract each other, these substances usually only occur when a metal bonds with a non-metal, forming metal salts, which have very high melting and boiling points.
The general rule;
Metal + Acid ---> Metal Salt + Hydrogen
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