Question

How do the atoms combine in magnesium oxide, ${\text{MgO}}$?
A. coordinate covalent way
B. Covalent way
C. Ionic way
D. None of these

Answer 1

Hint: A chemical bond is a lasting attraction between atoms that enables the formation of chemical compounds. Atoms of these elements lose, gain or share outer electrons to attain the noble gas configuration and form compounds.

Complete step by step answer:
Atoms of most elements are reactive because they do not have the noble gas structure, i.e. their outer shells are not completely filled.
There are different types of bonds-ionic, covalent, coordinate, coordinate covalent, hydrogen, metallic bonding etc.
Atoms share electrons to attain noble gas configuration. This type of bonding is called covalent bonding. A covalent bond in which both the electrons are donated by one of the atoms is called coordinate covalent bond. It is represented by an arrow. Atoms gain or lose electrons to attain noble gas configuration. This type of bonding is called ionic bonding.
Here, magnesium has a total of twelve electrons. It can be written as $2,8,2$.Oxygen has a total of eight electrons. It can be written as $2,6$. Magnesium has two electrons in its valence shell, i.e. outermost shell. While oxygen has six electrons in its valence shell. To attain noble gas configuration, magnesium has to lose two electrons so that it can attain configuration of neon gas. Oxygen has to gain two electrons so that it can attain configuration of neon.
So when magnesium transfers its two electrons to oxygen, thereby oxygen gets two electrons. So both attain noble gas configuration of neon. Thus it forms an ionic bond between them.

So, the correct answer is Option C .

Note:
In the formation of an ionic bond between magnesium and oxygen, magnesium forms positive ions ($ + 2$ ) and oxygen forms $ - 2$ negative ions. Positive ions are called cations and negative ions are called anions. Cations are formed by losing electrons while anions are formed by gaining electrons.