Put the following series of oxides in order of increasing...

Put the following series of oxides in order of increasing melting points and decide which are gases at room temperature: $4.1 \mathrm{Na}_2 \mathrm{O}, \mathrm{Cr}_2 \mathrm{O}_3, \mathrm{CO}_2, \mathrm{SiO}_2, \mathrm{P}_4 \mathrm{O}_{10}$ $4.2 \mathrm{ZrO}_2, \mathrm{CO}_2, \mathrm{SrO}, \mathrm{Rb}_2 \mathrm{O}, \mathrm{Y}_2 \mathrm{O}_3$

Put the following series of oxides in order of increasing melting points and decide which are gases at room temperature:
$4.1 \mathrm{Na}_2 \mathrm{O}, \mathrm{Cr}_2 \mathrm{O}_3, \mathrm{CO}_2, \mathrm{SiO}_2, \mathrm{P}_4 \mathrm{O}_{10}$
$4.2 \mathrm{ZrO}_2, \mathrm{CO}_2, \mathrm{SrO}, \mathrm{Rb}_2 \mathrm{O}, \mathrm{Y}_2 \mathrm{O}_3$

Key Concepts

Physical State Determination

This concept pertains to identifying whether a substance is a gas, liquid, or solid at room temperature based on its molecular size, bonding, and melting point. Molecular oxides with low melting points often exist as gases under ambient conditions, whereas ionic and network covalent oxides are typically solids.

Network Covalent Structures

Network covalent structures, such as those seen in some oxides, are characterized by a continuous network of strong covalent bonds that extend throughout the material. This extensive bonding results in extremely high melting points, as a significant amount of energy is required to break the network apart.

Melting Point Trends

This concept involves understanding how different types of bonding and molecular structures influence the energy required to overcome intermolecular or interatomic forces. It explains why certain oxides, such as network covalent structures, have high melting points, while molecular compounds generally have much lower melting points due to weaker Van der Waals forces.

Ionic versus Covalent Bonding

Understanding the distinction between ionic and covalent bonding is essential in predicting melting points and physical states. Ionic compounds, formed by the electrostatic attractions between oppositely charged ions, typically exhibit high melting points. In contrast, covalently bonded molecular oxides usually have much lower melting points and can exist as gases at room temperature.

Transcript

00:01 Let's start this question by remembering the four different types of crystals that we have.

00:06 The four types are ionic crystals, covalent crystals, molecular crystals, and metallic crystals.

00:24 Now, let's remember what each of these different types are categorized.

00:29 Ionic crystals have ions, evidently, as the name would suggest, and they have very high, melting points.

00:42 Now covalent, these exist by covalent bonds, so we know that their bonds are indeed covalent bonds, and they form a network, and they're also going to have high melting points, not as high as the ionic, but they are still going to have high melting points.

01:06 Molecular are categorized by the fact that they don't form these networks like our covalence, but they do still form attractions to each other through things like vanderwals attractions and they're going to have lower melting points and then last but not least we have our metallic and that is just our pure metal forming crystals.

01:35 So let's take a look at what they've given us and go down the line as we categorize them.

01:42 So first things first, we have an a2o.

01:46 Well, right away we realize that we're working with an ionic crystal because we're given sodium and oxygen.

01:54 So let's go ahead and put na2o in our ionic category.

02:00 Next, we have mgo.

02:03 That's also going to be a good example of an ionic crystal because magnesium and oxygen are ions together in that state.

02:13 Then we have al203...