Formulae Of Ionic Compounds & Their Names - Part 1 | Properties of Matter | Chemistry | FuseSchool

Summary

This educational script introduces the formation and nomenclature of ionic compounds. It demonstrates the process of writing and naming formulas for ionic compounds through examples, such as NaCl (sodium chloride) and MgO (magnesium oxide). The script emphasizes the importance of balancing charges in ionic compounds, as seen in CaF2 (calcium fluoride) and Al2S3 (aluminum sulfide), and provides a step-by-step guide to deducing the formula and name of ionic compounds from their constituent ions.

Takeaways

• 🧪 Ionic bonds are the electrostatic attraction between oppositely charged ions.
• 🔋 Na+ ion is formed when sodium loses one electron, which is then transferred to a Cl atom to form Cl-.
• ✍️ To write the formula for an ionic compound, write the ions side by side with their charges in superscript, then criss-cross the charges to form subscripts.
• 🔄 The resulting formula for sodium chloride is NaCl, where the positive metal ion (Na) comes first, followed by the negative non-metal ion (Cl).
• 📚 The naming rule for ionic compounds: for non-metal ions, the first syllable stays the same, but the ending changes to '-ide'.
• 🧊 Chlorine becomes chloride in NaCl, so the compound is called sodium chloride.
• 🧲 Another example: Mg2+ and O2- ions criss-cross to form MgO, called magnesium oxide.
• 🔍 When deducing the formula of ionic compounds, reduce the subscripts if possible, like Mg2O2 to MgO.
• 🧮 For Ca2+ and F- ions, the correct formula is CaF2, called calcium fluoride, balancing the charges by ensuring neutrality.
• 🔬 The formula for aluminum sulfide from Al3+ and S2- ions is Al2S3, maintaining the neutral charge of the compound.

Q & A

What is an ionic bond?

An ionic bond is the electrostatic attraction between oppositely charged ions, typically formed when one atom loses an electron to become a positive ion, and another atom gains that electron to become a negative ion.

How is the formula for an ionic compound determined?

The formula for an ionic compound is determined by criss-crossing the charges of the ions involved, bringing them down to subscripts, and reducing them if necessary to reflect the simplest ratio of ions that results in a neutral charge overall.

What is the correct formula for the ionic compound formed between sodium (Na) and chlorine (Cl)?

The correct formula is NaCl. Sodium (Na+) and chlorine (Cl-) combine in a 1:1 ratio to form sodium chloride.

How is the name of an ionic compound typically structured?

The name of an ionic compound starts with the positive metal ion, followed by the negative non-metal ion, whose name is modified by dropping the ending and replacing it with '-ide'.

What is the name of the compound with the formula MgO?

The name of the compound with the formula MgO is magnesium oxide. The 'ox' syllable from oxygen is kept, and the ending is replaced with '-ide'.

Why is the formula for MgO written as MgO instead of Mg2O2?

The formula Mg2O2 is reduced to MgO because the ratio of magnesium ions (Mg2+) to oxygen ions (O2-) is 1:1, which simplifies to the formula MgO.

What is the formula and name for the ionic compound formed between calcium (Ca) and fluorine (F)?

The formula is CaF2, and the name of the compound is calcium fluoride. Calcium (Ca2+) bonds with two fluorine ions (F-) to balance the charges.

Why is it important for ionic compounds to have a neutral overall charge?

Ionic compounds must have a neutral overall charge to maintain stability. This means that the total positive charge must balance the total negative charge in the compound.

What is the formula and name for the ionic compound formed between aluminum (Al) and sulfur (S)?

The formula is Al2S3, and the name of the compound is aluminum sulfide. Aluminum (Al3+) bonds with sulfur (S2-) in a 2:3 ratio to balance the charges.

What happens to the charge numbers when writing the formula of an ionic compound?

The charge numbers of the ions are criss-crossed and brought down as subscripts in the formula. If possible, the subscripts are simplified to the lowest whole number ratio, which ensures the formula reflects the simplest ratio of ions that maintains a neutral overall charge.

Outlines

00:00

🧲 Understanding Ionic Bonding and Naming Compounds

This paragraph introduces the concept of ionic bonding, which is the electrostatic attraction between oppositely charged ions. It explains the process of forming ions and provides a step-by-step guide on how to write and name ionic compounds. The example of sodium chloride (NaCl) is used to illustrate the method of criss-crossing charges to determine the formula and name of the compound. The importance of the metal ion coming first in both formula and name is emphasized, and the process is further explained with magnesium oxide (MgO), showing how to simplify ratios to achieve the correct formula.

Keywords

💡Ionic Bond

An ionic bond is a type of chemical bond formed by the electrostatic attraction between oppositely charged ions. In the video, it is explained that this bond occurs when a metal atom loses electrons and a non-metal atom gains those electrons, resulting in ions with opposite charges that attract each other. The formation of NaCl from Na+ and Cl- ions is used as an example to illustrate this concept.

💡Ion

An ion is an atom or molecule that has a net electric charge due to the loss or gain of one or more electrons. The video script describes how sodium (Na) becomes a Na+ ion by losing an electron and how chlorine (Cl) becomes a Cl- ion by gaining an electron. Ions are fundamental to the formation of ionic compounds.

💡Charge

In the context of chemistry, charge refers to the electrical property of an ion resulting from the loss or gain of electrons. The video emphasizes the importance of noting the charges of ions, such as Na+ and Cl-, and how these charges are written in superscript and criss-crossed to determine the formula of an ionic compound.

💡Formula

A chemical formula represents the composition of a substance, indicating the elements present and the number of atoms of each element in a molecule or compound. The video demonstrates how to write the formula of an ionic compound by balancing the charges of the ions, as shown with the examples of NaCl and MgO.

💡Naming Ionic Compounds

The process of naming ionic compounds involves stating the name of the metal first, followed by the name of the non-metal with the suffix '-ide'. The video script explains this process using the example of sodium chloride (NaCl) and magnesium oxide (MgO), highlighting the naming conventions for ionic compounds.

💡Metal

A metal is a type of element that tends to lose electrons to form positive ions, or cations. In the video, metals like sodium (Na) and magnesium (Mg) are mentioned as elements that lose electrons to bond with non-metals through ionic bonds, forming compounds like NaCl and MgO.

💡Non-metal

A non-metal is an element that tends to gain electrons to form negative ions, or anions. The video script uses chlorine (Cl) and oxygen (O) as examples of non-metals that gain electrons to form Cl- and O2- ions, respectively, which then bond with metal ions to form ionic compounds.

💡Criss-cross Method

The criss-cross method is a technique used to determine the formula of an ionic compound by balancing the charges of the ions involved. The video demonstrates this method by writing the charges of the ions side by side, circling them, and then criss-crossing to simplify the formula, as seen with the examples of NaCl and MgO.

💡Subscript

In chemistry, a subscript number indicates the number of atoms of an element in a molecule or compound. The video mentions that when writing chemical formulas, the charges of the ions are brought down as subscripts, and if the number is '1', it is not written, as in the case of NaCl.

💡Balancing Charges

Balancing charges is the process of ensuring that the total positive charge from the metal ions equals the total negative charge from the non-metal ions in an ionic compound, resulting in a neutral compound. The video script explains this with the example of calcium fluoride (CaF2), where one Ca2+ ion bonds with two F- ions to balance the charges.

💡Neutral Charge

A neutral charge means that the total charge of an object or compound is zero, with no net positive or negative charge. The video emphasizes that ionic compounds must have an overall neutral charge, which is achieved by balancing the charges of the ions, as illustrated with the formation of CaF2 from Ca2+ and two F- ions.

Highlights

Ions are formed through the loss or gain of electrons.

An ionic bond is the electrostatic attraction between oppositely charged ions.

The process of naming ionic compounds involves understanding their charges.

Example given: Na loses one electron to form a Na+ ion.

Cl atom gains an electron to form a Cl- ion.

Method to write down ions and their charges in superscript.

The criss-cross method to determine the formula of ionic compounds.

The rule that the number 'one' is not written in chemical formulas.

NaCl is the resulting formula for sodium and chlorine ions.

Metal ions are placed first in both formula and name.

Non-metal ions have their endings replaced with '-ide'.

Chlorine is named as chloride in ionic compounds.

Sodium chloride is the name of the NaCl compound.

Mg and O form the compound MgO with a 1:1 ratio.

Oxygen is named as oxide in ionic compounds.

Ionic compounds must have an overall neutral charge.

Ca2+ forms an ionic bond with two F- to balance charges, resulting in CaF2.

CaF2 is named calcium fluoride.

Al and S form the compound Al2S3, named aluminum sulfide.

Transcripts

We have learned about how ions are formed and that an ionic bond is the electrostatic

attraction between oppositely charged ions.

We will now learn about how to name these ionic compounds and deduce their formula from

the ionic charges.

Let's warm up with a simple example.

We know that Na loses one electron to form a Na+ ion.

We also know that the electron is not "lost", but transferred to a Cl atom to form a Cl-

ion.

Do you have a piece of paper and a pencil on hand?

Let's grab those and work on this example together!

1) Write down the ions side by side along with their charges -- remember that the charges

are written in superscript. 2) Now, circle the charges, and criss-cross

them, just like how it is done here, bringing down the charges so that they are in subscript.

One is never written in a formula -- it is assumed no number written means that there

is one atom.

So, the resulting formula is NaCl -- did you get that, too?

The positive metal ion always comes first in both the formula and the name.

For the negative non-metal ions, the first syllable stays the same, but the ending is

dropped and replaced with "-ide".

Chlorine becomes chloride.

So this ionic compound is called sodium chloride.

Keep that piece of paper because we will do another example, this time with Mg and O.

Let's write the ions, along with their charges, side by side.

Then, we will criss-cross the charges.

We should get the following formula Mg2O2, but 2:2 can be reduced to 1:1.

Therefore the formula is MgO.

The name of this compound is magnesium oxide.

Remember that we keep the first syllable in oxygen, "ox", and the ending is changed to

"-ide" On your own, find the formula and the name

of the ionic compound formed from Ca and F. Please pause the lesson and resume once you

are done to check the answer.

The formula is CaF2, with the "2" written in subscript, and the name is calcium fluoride.

If we think about it, everything we've described makes perfect sense.

We know that ionic compounds have an overall neutral charge, so all charges present must

be balanced.

Using your calcium fluoride example, we can see that to balance the charges, the Ca2+

ion must form an ionic bond with two F-ions.

This concept is stitched together when writing its formula -- CaF2

We will do one more example together -- this time with Al and S

The formula is Al2S3 and the name is aluminum sulfide.