Donnez les formules des composés suivants : a) nitrite de rubidium; b) sulfure de potassium; c)

Donnez les formules des composés suivants : a) nitrite de...

Key Concepts

Ionic Compound Nomenclature

This concept involves the rules and systematic procedures for naming compounds that consist of positive and negative ions. It includes understanding how to pair cations and anions in proper stoichiometric ratios to yield a neutral compound, and it is crucial for deducing or writing the correct chemical formulas from names.

Polyatomic Ions

Polyatomic ions are charged particles composed of several atoms bound together, which act as a single unit in ionic compounds. Recognizing common polyatomic ions (such as sulfate, phosphate, nitrite, perchlorate, etc.) and their corresponding charges is essential for writing correct formulas and understanding the structure of many chemical compounds.

Oxidation States and Transition Metals

The oxidation state of an element, especially transition metals which can adopt multiple oxidation numbers, is indicated in compound names (for example, iron(III)). This notation is crucial for assigning the correct charge to the metal, ensuring the compound’s formula is electrically neutral, and guiding the proper construction of the compound's chemical formula.

Acid Nomenclature

Acid nomenclature involves the rules for naming acids, which typically contain hydrogen and a nonmetal polyatomic ion. This concept is important for identifying compounds like perbromic acid, where the naming indicates the presence of both hydrogen and a specific oxyanion with defined stoichiometry.

Hydrated Compounds

Hydrated compounds incorporate specific amounts of water molecules into their crystalline structure, usually denoted by appended water molecules in the compound’s formula (e.g., dihydraté indicates two water molecules). Understanding how to represent these water molecules is essential for accurately depicting the total composition of such compounds.

Transcript

00:01 The goal of the problem is to determine the chemical formulas of the following compounds.

00:06 Let's first start with ribidium nitrate.

00:10 Rebidium is rb plus and nitrite is no2 minus.

00:16 The next step would be to cross the charges.

00:19 What i mean by this is that the charge of the ribidium would end up being the subscript for the nitrite.

00:26 And the charge of the nitrite, which is a minus, would be the subscript for the ribidium.

00:32 So when we write it, we would write it as rb, n02, since both of them have a one charge, plus and minus.

00:41 Next is potassium sulfide.

00:43 Potassium is k plus, while sulfide is an s -2 -minus.

00:49 So when we cross the charges, the two would be the subscript for k, and s would have a subscript of 1, leading to k -2s.

00:58 Next we have sodium hydrogen sulfide.

01:01 Sodium has a plus 1 charge, hydrogen has a plus 1 charge as well, and sulfide has a 2 minus charge.

01:11 Now since there's 3 ions, we have to balance the charges.

01:15 The n -a and h have a plus plus charge, and the s has a 2 -minus charge.

01:20 Therefore the charges will be balanced, and you just need to write the ions as it's.

01:24 So we write nahs, and that would be our ionic compound.

01:30 Next we have magnesium phosphate.

01:32 Magnesium has a plus 2 charge, and phosphate is p .04, 3 minus.

01:38 So when we cross the charges, m .g would get the 3 minus charge, you would get m .g 3, and p .o4 would get the plus 2 charge.

01:47 So our full compound would be mg3, p .o .4 .2.

01:51 Next we have calcium hydrogen, hydrogen, phosphate.

01:54 Calcium has a plus 2 charge, hydrogen has a plus charge, and phosphate has a 3 minus charge.

02:00 Similar to a previous problem, you just need to add up the charges and balance them.

02:05 So since ca and h both have plus and plus, they add up to 3 plus, which would balance out with the 3 minus...

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