The placement of metal and non-metal elements in the periodic table makes it possible to predict the formation of compounds. Which of the following chemical formulas indicates the formation of an ionic compound?

a. KI
b. ICI
c. SO3 (the three is small)
d. CHCL3 (the three is small)
I understand what the question is asking, but I'm not sure on how to get the answer. Would I need to know all the elements in the periodic table to answer this?

To determine which of the given chemical formulas indicates the formation of an ionic compound, you do not need to know all the elements in the periodic table. Instead, you need to understand the general characteristics of ionic compounds.

Ionic compounds are formed between metals and non-metals through the transfer of electrons. Metals tend to lose electrons and become positively charged ions (cations), while non-metals tend to gain electrons and become negatively charged ions (anions). The resulting electrostatic attraction between the oppositely charged ions holds the compound together in a crystal lattice structure.

Let's analyze the given options:

a. KI: Potassium (K) is a metal, and iodine (I) is a non-metal. The combination of a metal and non-metal indicates the formation of an ionic compound. Therefore, KI is likely an ionic compound.

b. ICI: Both iodine atoms (I) are non-metals. The combination of two non-metals typically results in a covalent compound, rather than an ionic compound.

c. SO3: Sulfur (S) is a non-metal, and oxygen (O) is also a non-metal. Like the previous option, this combination suggests a covalent compound rather than an ionic compound.

d. CHCl3: Carbon (C) and chlorine (Cl) are both non-metals. This formula represents a covalent compound.

Based on the analysis, option a. KI is the only one that indicates the formation of an ionic compound.