Derive the correct formulas for the following ionic compounds by writing Lewis structures. (a) l

Derive the correct formulas for the following ionic...

Key Concepts

Ionic Compounds

Ionic compounds are formed by the electrostatic attraction between positively charged ions (cations) and negatively charged ions (anions). The formation of these compounds involves the transfer of electrons from one atom to another, resulting in ions that combine in proportions that yield an electrically neutral compound.

Ionic Bonding

Ionic bonding is the chemical bonding process through which ions with opposite charges attract each other. This type of bond is typically established between metals, which tend to lose electrons, and nonmetals, which tend to gain electrons, leading to the formation of a stable electron configuration resembling that of the noble gases.

Lewis Structures

Lewis structures are diagrams that show the bonding between atoms and the lone pairs of electrons that may exist in a molecule or ion. In the context of ionic compounds, Lewis structures help visualize the electron transfer process and the resulting charged ions, even though the bonds in ionic compounds are primarily electrostatic rather than shared electron pairs.

Charge Neutrality

Charge neutrality is a key principle in the formation of ionic compounds, where the total positive charge from the cations must balance the total negative charge from the anions. This ensures that the compound as a whole is electrically neutral, and it guides the determination of the correct stoichiometric ratios in the chemical formula.

Valence Electrons

Valence electrons are the electrons in the outermost shell of an atom that participate in chemical bonding. Understanding the number of valence electrons is essential when drawing Lewis structures because it helps determine how atoms transfer or share electrons to achieve a stable configuration, typically following the octet rule.

Transcript

00:01 Here i have an overview of the steps that we will be following to find the correct formulas for each of these ionic compounds that we're given, and then draw the lewd structures for each one of them.

00:10 And so let's just go ahead and look at our first one, lithium sulfide.

00:14 And so we can, drawing the element samples here, we have l -i -n -s.

00:17 And so the first thing that we're going to do is write the formula out for this ionic compound.

00:21 And so we can write the ionic charges for each one of these ions based on the numbers given here above the periodic.

00:30 Table.

00:31 And so after we do this, we can use something called the crisscross method to find out what the formula is.

00:40 And so if we take each number and essentially crisscross it, this gives us the formula.

00:49 And so now that we know that we have two lithium ions and only one sulfide ion, we can draw these ions out and separate them.

00:56 And then we can add the valence electrons as dots.

00:59 And right now we aren't considering any charges.

01:02 And so let's just draw them out based on what we know from the periodic table.

01:06 So lithium has one.

01:08 And then sulfur will have six.

01:12 And then again, lithium has one.

01:14 And so what we can do now is look at the charges.

01:18 And then this will change the lewis structure.

01:21 And so because we know that lithium has a plus one ionic charge, this means that we will need to remove an electron.

01:31 And this is because whenever you have a plus one charge, this means that there will be an additional proton.

01:37 And so, such as with sulfide with a minus two charge, this means that there will be an additional two electrons because electrons are negative, protons are positive, and so that's the way that you can remember it.

01:51 And so because we know that we are going to subtract one electron here.

01:56 We know that we are going to subtract one electron over here on this lithium ion as well.

02:03 And so because of this minus two charge, we will be adding two electrons to this sulfide ion, giving us this final formula here.

02:15 And so we can go ahead and look at our next one.

02:18 We have sodium fluoride.

02:22 And so, again, we will go through the same steps of finding out the formula and then separating out the ion.

02:37 And so here we can see that the formula shows that there is only one sodium ion and one fluoride ion.

02:45 And so we can draw these out just as before and then surround these with their valence electrons as dots.

02:53 So sodium has one valence electron and fluoride, fluorine will have only seven.

03:06 And so now we can add their charges.

03:08 So we know that because that there is a plus one charge, you're going to have to take away an electron because of this plus one charge...

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