Question

why?
when you began chemistry class this year, you probably already knew that the chemical formula for car - bon dioxide was co₂. today you will find out why co₂ is named that way. naming chemical compounds correctly is of paramount importance. the slight difference between the names carbon monoxide (co, a poisonous, deadly gas) and carbon dioxide (co₂, a greenhouse gas that we exhale when we breathe out) can be the difference between life and death! in this activity you will learn the naming system for molecu - lar compounds.
model 1 - molecular compounds

molecular formula	number of atoms of first element	number of atoms of second element	name of compound
cf₅	1	5	chlorine pentafluoride
co	1	1	carbon monoxide
co₂	1	2	carbon dioxide
cl₂o	2	1	dichlorine monoxide
pcl₅	1	5	phosphorus pentachloride
n₂o₅	2	5	dinitrogen pentoxide

1. fill in the table to indicate the number of atoms of each type in the molecular formula.
2. ionic compounds have a metal and a non - metal in them. molecules like those in model 1 are called molecular compounds. do the molecules in model 1 have a metal and non - metal or 2 non - metals? are the compounds in model 1 ionic or molecular?
3. what is different about the names in model 1 than the name of ionic compounds we named last week?
4. cf and cf₅ both have chlorine and fluorine in them. why is the name “chlorine fluoride” not sufficient to identify these compounds?
5. the name of the compound gives a clue to its molecular formula. how many fluoride atoms are there in carbon monofluoride? using the trends in model 1, predict how many atoms each of these prefixes indicates.

Explanation:

Step1: Analyze molecular formulas

For each compound in the table, count the number of atoms of each element based on the sub - scripts in the molecular formula. For example, in $CO_2$, there is 1 carbon atom and 2 oxygen atoms.

Step2: Determine compound type

Molecular compounds in Model 1 consist of non - metals only. Since there are no metals in these compounds, they are molecular, not ionic.

Step3: Compare naming

Names of molecular compounds in Model 1 use prefixes (mono -, di -, penta - etc.) to indicate the number of atoms of each element. Ionic compound names do not use such prefixes in the same way.

Step4: Consider atom ratios

$ClF$ has a 1:1 ratio of chlorine to fluorine, while $ClF_5$ has a 1:5 ratio. The name "chlorine fluoride" does not specify the ratio, so it is not sufficient.

Step5: Predict from naming

In carbon monofluoride, "mono -" indicates 1 fluorine atom.

Answer:

1. For $ClF$: 1 chlorine atom, 1 fluorine atom; for $ClF_5$: 1 chlorine atom, 5 fluorine atoms; for $CO$: 1 carbon atom, 1 oxygen atom; for $CO_2$: 1 carbon atom, 2 oxygen atoms; for $Cl_2O$: 2 chlorine atoms, 1 oxygen atom; for $PCl_5$: 1 phosphorus atom, 5 chlorine atoms; for $N_2O_5$: 2 nitrogen atoms, 5 oxygen atoms.
2. The molecules in Model 1 have 2 non - metals. The compounds in Model 1 are molecular.
3. Molecular compound names in Model 1 use prefixes to indicate the number of atoms of each element, while ionic compound names do not use prefixes in the same way.
4. Because $ClF$ and $ClF_5$ have different ratios of chlorine to fluorine atoms, and "chlorine fluoride" does not specify the ratio.
5. There is 1 fluorine atom in carbon monofluoride.