Which of the following molecules is held together primarily by ionic bonds? How do you determine this?

What makes an ionic bond is a large difference between the electo negativities of the that are bonding. Many periodic tables will list the electro negativities. Alternatively the electro negativities can be found in a table or index in the back of a chemistry textbook.

A. H-H As both atoms are hydrogen with an electro negativity of 2.1 -2.1 = 0 This is a pure covalent bond. called a non polar covalent bond.

B. H- O is a polar covalent bond Oxygen has an electro negativity of 3.5 - 2.1 = 1.4

C. Na- Cl is an ionic bond Na has an electro negativity of 0.9 Chlorine has an electro negativity of 3.0 3.0- 0.9 = 2.1 a large difference.

( Generally an ionic bond forms when a metallic atom joins with a non metal or metalloid atom. or negative ion ( cation)

D. Carbon has an electro negativity of 2.5 When Carbon bonds with the Hydrogen ( as it does) the difference is 2.5 - 2.1 = 0.4 This bond is only slightly polar, and definitely covalent. ( co ; community, cooperate, working together.) When Carbon bonds with the Oxygen ( as it does) the difference is 3.5 - 2.1 = 1.0 polar covalent but not as strongly as the H- O bond. Sugar then is covalent molecule, not ionic.

E. Nitrogen has an electro negativity of 3.0 so 3.0 -2.1 = 0.9 again only slightly polar and definitely covalent.

Ionic bonds form between these oppositely charged ions due to electrostatic attraction; to identify which molecule is primarily held together by ionic bonds, you would look for the presence of ions in the chemical formula and assess the electronegativity difference between the atoms involved; if the difference is large (usually greater than 1.7), it suggests ionic bonding. The molecule made up of ions is the one that is primarily held together by ionic bonds; one or more atoms have gained electrons (anions) and one or more atoms have lost electrons (cations).