For each of the following ions, indicate the total number of...

Key Concepts

Ions and Their Charges

This concept refers to atoms or groups of atoms that have lost or gained electrons, resulting in a net positive or negative charge. Understanding the number of protons (which remains constant for an element) versus the variable number of electrons is key. Positive ions (cations) have fewer electrons than protons, while negative ions (anions) have more electrons than protons. This principle is fundamental when determining the electron/proton count in any charged species.

Charge Neutrality in Ionic Compounds

Ionic compounds are formed by combining ions such that the overall charge of the compound is zero. This involves balancing the total positive charges from cations with the total negative charges from anions using the smallest whole number ratio. The process of determining the correct formula for the simplest compound relies on understanding and applying this principle of charge neutrality.

Ionic Compound Nomenclature

This concept involves the systematic method of naming ionic compounds by identifying the cation and anion components. Typically, the name of the cation is given first, followed by the anion, with specific naming conventions for polyatomic ions. Mastery of ionic nomenclature is essential to accurately name compounds formed in various reactions, including those involving common species like the oxide ion or ions from metallic elements.

Transcript

00:01 So in this video we're going to talk about question 100 from chapter 2, which says for each of the following ions indicate the total number of protons and electrons in the ion.

00:11 For the positive ions in the list, predict the formula of the simplest compound form between each positive ion and the oxide ion.

00:20 Name the compounds.

00:21 For the negative ions in the list, predict the formula of the simplest compound form between each negative ion and the aluminum ion.

00:28 Name the compounds.

00:29 So in a, we have fe2 plus.

00:32 So we're going to need to consult the periodic table for the atomic number of iron, fe.

00:42 And we're going to use that to determine the number of electrons, the number of protons that we have.

00:48 So let's look at the periodic table for fe.

00:50 So iron is here in the middle of the d block, in the middle of our transition metals, and it has an atomic number of 26.

00:58 So iron has 26 protons.

01:04 And the fact that it has a positive 2 charge means that it has two fewer electrons than protons.

01:10 We have two more of our positively charged particles than our negatively charged particles.

01:14 So we only have 24 electrons.

01:17 And then we want to predict the formula of the simplest compound form between iron and the oxide ion.

01:24 So we have iron with a plus 2 charge and oxygen, which takes a, net minus 2 charge, so this is already balanced.

01:33 So we have feo would be the simplest possible compound.

01:38 In b, we have fe3 plus.

01:40 So again, we have 26 protons because we have iron.

01:44 The atomic number is the same.

01:47 But this time, our positive charge is 3 plus instead of 2 plus, so we have three fewer electrons than protons.

01:54 So we have 23 electrons.

01:57 And then when we're writing the formula for the compound it forms with oxide, we have a positive three charge and a minus two charge, so we're going to need two of our positively charged ions and three of our negatively charged ions that gives us plus six and minus six that should balance each other out.

02:18 So the simplest possible compound that fe3 plus can form with oxide is fe2 .03.

02:27 And c, we have barium 2 plus.

02:30 So let's take a peek at the periodic table to find barium.

02:34 Um, so barium is over here, um, in our alkaline earth metals.

02:39 Its atomic number is 56 over here.

02:43 Um, so atomic number is 56.

02:45 That tells us we have 56 protons.

02:48 How many electrons do we have? well, because of our plus two charge, we have two fewer electrons than protons.

02:54 So we have 54 electrons.

02:56 And then we want to know what compound barium 2 plus will form with oxygen to minus.

03:04 And since those triages balance each other out, plus 2 and minus 2, we just have b .a .o would be the simple as possible compound that barium can form with oxide.

03:16 In d, we have cs plus.

03:22 So we have cesium plus 1.

03:24 So let's look on the periodic table for cesium.

03:27 So cesium is here right next to barium.

03:30 It has an atomic number of 55, so we know that we have 55 protons.

03:36 And then since we have a plus 1 charge, we know that we have one fewer electron than protons.

03:41 So we only have 54 electrons.

03:44 And then we want to know what compound it will form with oxide.

03:49 Well, if our cesium has a plus 1 charge and our oxygen has a minus 2 charge, then we need 2 of our cesium.

03:55 So we have cs2o.

03:58 In e, we have sulfur with a minus 2 charge.

04:03 So how many protons does sulfur have? what's the atomic number of sulfur? so sulfur is over here in our non -metals with an atomic number of 16.

04:13 So we have 16 protons...

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