I was wondering if somebody could help me with this...
Classify the following substances as covalent molecules or ionic compounds:
a. MgO e. LiCl
b. NI3 f. SF4
c. CuS g. XeF4
d. NO2 h. CsF
How do you know if they are covalent or ionic bonds?
Metal + nonmetal is usually ionic
Two nonmetals joined are usually covalent.
so CuS g. XeF4 would be ioninc right?
No. XeF4 is covalent, and CuS is ionic (to an extent).
To add to the excellent answer given to you by Bob Pursley, you may want to look in your text and read about electronegativity. That is a man-made scale that allows us to compare the ability of atoms to attract electrons. By taking the difference between the EN (electronegativity) of two elements, we can assign the degree of ionic or covalent character to the bond formed. Here is a site that will give you some more information. http://en.wikipedia.org/wiki/Electronegativity
To determine whether a substance is an ionic compound or a covalent molecule, you can consider the types of elements involved and their electronegativity.
Ionic compounds typically form between a metal and a nonmetal. In these compounds, the metal atom loses electron(s) to form a positive ion (cation), while the nonmetal atom gains these electron(s) to form a negative ion (anion). The resulting attraction between oppositely charged ions forms an ionic bond. Examples of ionic compounds in the given list are MgO (magnesium oxide), LiCl (lithium chloride), and CsF (cesium fluoride).
On the other hand, covalent molecules are formed between two nonmetals. In covalent bonds, atoms share electrons to achieve a stable electron configuration. Examples of covalent molecules in the given list are NI3 (nitrogen triiodide), SF4 (sulfur tetrafluoride), and XeF4 (xenon tetrafluoride).
However, determining the exact nature of a bond can be more complicated and may require considering the electronegativity difference between the elements involved. Electronegativity is the ability of an atom to attract electrons towards itself in a covalent bond.
If the electronegativity difference between two elements is large (usually greater than 1.7), the bond formed is more likely to be ionic. If the electronegativity difference is small (usually less than 1.7), the bond is likely to be covalent.
In the given examples, CuS (copper sulfide) is primarily ionic, as copper (Cu) is a metal and sulfur (S) is a nonmetal. XeF4 (xenon tetrafluoride) is primarily covalent, as both xenon (Xe) and fluorine (F) are nonmetals.
To summarize:
- MgO, LiCl, and CsF are ionic compounds as they are formed between metals and nonmetals.
- NI3, SF4, and XeF4 are covalent molecules as they are formed between nonmetals.
Remember, these classifications are general guidelines, and there can be exceptions and variations in specific cases.