## Wednesday, July 29, 2020

### States of Matter

Where are we going with this?
The point of this deck is to provide concepts,background information and examples related to the kinetic theory of matter. Using this model will help predict behaviors of substances within a variety of environments.

States (Phases) of Matter
Why does it have two names?

There are five phases of matter.

Matter can be observed in different forms which change as the temperature changes. Most people are very familiar with three of the phases. The other two are a little less commonly recognized.

The differences in the phases (states) can be determined based on how a couple of physical characteristics are observed. Also, for the two less common, the state is determined based on (to keep it conversations) how the parts of the atom are arranged.

Before we define and look at characteristics of the different phases, a quick note. Matter will exist in different states depending on the temperature. As temperature changes, matter will undergo phase changes (state changes).

Let's start with the three common ones: solids, liquids, and gasses

The physical characteristics that determine the difference between solids, liquids, and gases deal with shape and volume.

Regarding shape, the question that separates solids, liquids and gasses is whether or not the shape is fixed and definite or not. Without banging on it, will the shape change to fit the shape of its container? If you place it on the desk, will the shape stay the same?

If you put a cube of metal, a glass beaker, or even a grain of sand on the desk, it will retain its shape. If you have a square jug of water, and pour the contents (the water) on the desk, the water will not remain a square.
But ice would.

Regarding volume, the question that separates solids, liquids, and gasses is whether or not the volume can be changed as the volume of the container changes. If you have water in a glass and pour it into a bowl, the amount of the water stays the same. If you have 4 yards of gravel in a truck, then you spread all that out to make a driveway, the volume is still 4 yards of gravel. The shape changed (from the shape of the truck to the shape of the driveway).

How the above two questions are answered determines if something is a solid, liquid or gas.

Solids

Matter in the solid state has BOTH a definite volume AND a definite, fixed shape.

Liquids

Matter in the liquid state has a definite volume BUT NOT a definite, fixed shape.

Liquids will keep the same volume as you pour from container to container, but they will take the shape of whatever container they are in.

Gasses

Matter in the gas state has NEITHER a definite volume NOR a definite, fixed shape.

Gases will expand or contract to fill the space available.

Two more phases of matter:

Plasma

Matter in the gas plasma has NEITHER a definite volume NOR a definite, fixed shape AND…

Plasmas are super high energy. So much so that the electrons have separated from the nuclei. This will be discussed more within the scope of kinetic theory.

Condensate / Bose-Einstein Condensate / BEC

Matter in this phase (state) is really more of a concept related to kinetic energy and motion of particles. Understanding it is better achieved within the context of kinetic theory. For purposes of this point of view, you can think of it this way.

Matter in this phase has collapsed into a big clump of electrons, protons, and neutrons, and has different properties as a result.

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Who doesn't like a chart?

 State Shape Volume Other Temperature Bose-Einstein Condensate N/A N/A Clump of sub-atomic particles EXTREMELY Low Solid Definite Definite Lower Liquid Indefinite Definite Low Gas Indefinite Indefinite High Plasma Indefinite Indefinite Electrons “shaken off” Higher

### Temperature, Kinetic Energy, and Molecular Motion

Where are we going with this?
The point of this deck is to provide concepts,background information and examples related to the kinetic theory of matter. Using this model will help predict behaviors of substances within a variety of environments and help quantify

Temperature, Kinetic Energy, and Molecular Motion

Let me just apologize on the front end… This concept spirals in on itself. And drag some other concepts into the vortex with it.

Let's jump into the shallow end first… Matter is made of particles. Hold that thought…

Okay, what else is easy? Everyone recognizes the concept of temperature. We ask things like, "How hot is it outside?" We say, "Wow! It's cold in here!"
Maybe no one actually says "wow" but…

So, the concept of temperature is intuitive, to some degree. Hold that thought…

Let's drag in the concept of energy into this spiral… Energy is a quantity that is the potential to do work, which is yet another concept—but we're going to skip over that… Back to energy…

Three are different ways to store energy. Energy can change forms, too, so (example) chemical energy stored in a car battery can be converted to electrical energy.

We're getting back to kinetic theory, now. One way to store energy (a type of energy) is thermal energy

Thermal… that sounds familiar?

Thermal energy is the energy that is stored within the motion of the particles that make up matter.

We're close now!

This brings us to the concept of temperature.

Temperature is a basic measurement that is related to the amount of thermal energy stored in a material. This energy is stored in the motion of the particles. As thermal energy is added, the molecules (let's say we're talking about a solid, and let's use a word we can visualize) vibrate within their relative position to other particles of the substance.

The amount of energy stored is a function of how fast the particles are moving (let's just keep thinking of them vibrating in place, for now) and how much mass each particle has. Of course there is a formula for energy associated with a moving object:

Ek = 1/2mv2
where Ek is kinetic energy, m is mass and v is velocity.

Thermal energy is the sum of all the kinetic energy of all particles of a substance.

This, at last, brings us to a definition of temperature:

Temperature is the average kinetic energy of the molecules in a sample.

So, temperature can be understood as the average kinetic energy of the molecules as they move in constant motion.

Now for the spiral!

Temperature is average kinetic energy, which is based on the changeable velocity of the particles.

If the velocity of the particles goes up, the the kinetic energy goes up (see the equation above). That means that the temperature goes up (since temperature is the average kinetic energy.

But, since we can't see the particles speeding up or slowing down, we generally rely on the temperature to tell is what they are doing.

We can measure the temperature of the water and say, "Well look! The temperature went up."

If that happens, then we can conclude that the particles are moving faster. If the temperature goes down, they are moving slower.

 Temperature Up Temperature Down Kinetic Energy Increases (by definition) Kinetic Energy Decreases (by definition) Particle velocity Increases (according to formula) Particle velocity Decreases (according to formula) Volume Usually Increases Volume Usually Decreases

 Not produced by art major.

### All Matter Is Made Of Particles

Where are we going with this?
The point of this deck is to provide concepts,background information and examples related to the kinetic theory of matter. Using this model will help predict behaviors of substances within a variety of environments and help quantify

Kinetic Theory of Matter: All matter is made up of particles.

Back to the properties of matter, particularly, the types of matter…

Matter can be classified into pure substances (elements and compounds) or mixtures (impure substances). Recall that a mixture is made of of two or more pure substances, so we can reduce our discussion of kinetic theory to pure substances (compounds and elements).
Because, within the mixture, you could isolate any of the pure substances and focus on that.

When you think about matter, it takes a little abstract thinking to zoom in all the way to the particle level. Suppose you are looking at a chunk of silicon. Naturally, you see the… chunk.

To think about what the chunk is made of takes a little abstract thinking. You have remember that silicon is an element, a pure substance. Then you have to imagine the atoms of the element somehow grouping up to form the silicon.

Likewise, thinking about a compound, you have to let your imagination take you down to the molecular level; all you can see with your eyes is the "chunk."

Many materials form crystals in which each atom is uniformly positioned in a set, fixed arrangement.

Other situations find particles of a substance in a mixture with water (e.g. a salt and water solution). You have to imagine some number salt molecules scattered among the water molecules (two compounds, by the way).

The point is, to get your head around kinetic theory, you need to let your thoughts grow to include the idea of particles of matter–atoms and molecules.

### Kinetic Theory of Matter: Basic Assumptions

Where are we going with this?
The point of this deck is to provide concepts,background information and examples related to the kinetic theory of matter. Using this model will help predict behaviors of substances within a variety of environments and help quantify

Kinetic Theory of Matter: Basic Assumptions

There are four basic assumptions of the kinetic theory of Matter:

1. All matter is made of particles.
Quick reminders… atoms… molecules… Matter is made up of these.

2. The particles of matter are in constant motion.
So… this is the first concept on a spiral of concepts regarding the motion of the particles of matter, the concept of temperature, and a type of energy related to mass and velocity of of the thing moving.

3. As temperature increases, the speed of the particles increases.
And also… as temperature goes down, the speed of the particles decreases. This goes back to that spiral of concepts, by the way.

4. As the speed of the particles increases, they take up more volume.
Except when they don't, but thats really rare.
Again, the opposite is true… Decreased temperature results in decreased volume.

## Wednesday, July 22, 2020

### Activity: Using Physical Properties to Identify a Substance

Where are we going with this?
The activity on this page is one means by which it is possible to differentiate between substances (pure and mixtures) based on physical and chemical properties.

Activity: Using Physical Properties to Identify a Substance

Overview: Some the physical properties of an unknown sample, can be used to identify the type of material of which the sample is composed.

If you do not have access to a centrifuge, you can complete this activity with this virtual lab video.

## Monday, July 20, 2020

### Evidence of Chemical Changes

Where are we going with this?
The point of this deck is to give the background information and examples so that we can differentiate between substances (pure and mixtures) based on physical and chemical properties.

Evidence of Chemical Changes

A chemical change occurs when a reaction takes place and you end up with substances that are different from those with which you started.

When chemical changes occur, there are usually physical changes and often other signs of the change. Some of those signs are…

A Change in Color
Many chemical changes result in the new substance showing a different color than the original.

https://youtu.be/Q91TWOcfP9w

Production of Gas
Some reactions release gas, and can be observed as bubbles or an odor.

Formation of a Precipitate
In liquid mixtures, chemical reactions will often cause the newly formed substances to take on a solid form and suspend more obviously in the liquid. This process is called formation of a precipitate.

The solid that forms in a liquid mixture is called a precipitate. The precipitate may remain suspended in the liquid, may settle to the bottom, or may float to the top.

Temperature Change

It is not uncommon for chemical changes to involve a noticeable temperature change. When a chemical change gives off heat (the system gets warmer), it is said to be exothermic. When a chemical change takes in heat (the system cools off), it is said to be endothermic.

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It is not always easy to tell if an observed change is physical or chemical. A heated piece of iron will change color, but still be iron. Gas bubbles will form when water's temperature approaches its boiling point, but it is still water.

For a chemical change to take place, two or more substances must change at the molecular level to become one or more NEW substances.

### Examples of Chemical Properties

Where are we going with this?
The point of this deck is to give the background information and examples so that we can differentiate between substances (pure and mixtures) based on physical and chemical properties.

Examples of Chemical Properties

A chemical property is any of a material's properties that becomes evident during or after a chemical reaction; that is, any quality that can be established only by changing a substance's chemical identity.

Two easily understandable chemical properties are flammability and reactivity.

Flammability
Flammability is a material's ability to burn in the presence of oxygen.

Burning is a chemical reaction in which molecules of the flammable substance combine with oxygen and give off energy that causes the air nearby to glow and give off light (flame).

Reactivity
Reactivity is the property that describes how readily a substance combines chemically with other substances.

Substances react with other substances in different ways. Some things are highly reactive and others are not. Oxygen is an example of something that reacts easily. Nitrogen is an example of something that does not.

Reactivity is often cited with relationship to a specific other substance. For instance different materials have different degrees of reactivity to water or reactivity to air.

Many chemical properties require a more advanced understanding of chemistry, but here are a some of them:

• Toxicity

• Types of chemical bonds that can be formed

• Heat of combustion: how much energy is given of when it burns

• Enthalpy of formation

• Acidity or basicity

________________________

Reactivity Virtual Lab

Properties of Matter Overview

### What are Chemical Properties of Matter?

Where are we going with this?
The point of this deck is to give the background information and examples so that we can differentiate between substances (pure and mixtures) based on physical and chemical properties.

What are Chemical Properties of Matter?

A chemical property is any of a material's properties that becomes evident during or after a chemical reaction; that is, any quality that can be established only by changing a substance's chemical identity.

Simply speaking, chemical properties cannot be determined just by viewing or touching the substance; the substance's internal structure must be affected greatly for its chemical properties to be investigated. When a substance goes under a chemical reaction, the properties will change drastically, resulting in chemical change.

So, what does this mean?

Chemical properties relate to how substances interact with other substances. You can't just look at something and measure a chemical property. A couple of points… Chemical properties are:
• are any ability to produce change in the composition of matter at the molecular level.
• can only be observed when the substances in a sample of matter change into different substances.

Since chemical properties relate to how substances interact, it is worthwhile to know when there has been a chemical reaction, when there has been some sort of chemical change to the substance or substances.

Chemical Changes

Chemical changes (which rely on chemical properties) occur, for instance, when:
• one or more substances react with other substances and form one or more NEW substances that are different in molecular composition compared to the original substances.

• one substance breaks down into two or more DIFFERENT substances that are different in molecular composition compared to the original substance.
So, something happens and you end up with substances that are different from what you began with. You burn some propane and end up with carbon dioxide and water, for example.

## Thursday, July 16, 2020

### What are Physical Properties of Matter?

Where are we going with this?
The point of this deck is to give the background information and examples so that we can differentiate between substances (pure and mixtures) based on physical and chemical properties.

What are Physical Properties of Matter?

physical property is any attribute, quality, or characteristic of a material that can be observed or measured without changing the composition of the substances in the material.

This "not changing the composition" thing is the key, here. It can change shape or even go from solid to liquid and be a physical property, but if it stops being something (like burning paper) then it is not a physical property.

The physical properties of a material can be used to help identify it. A sample can be compared to known quantities to determine if the sample is made from them. For example, if an unknown metal has a density of 10.5 g/cm, it might be silver. If the other properties of the unknown match other known properties of silver, then the conclusion that the sample is sliver might be well-founded.

Some physical properties are independent of the amount of the substance preset. Some physical properties change as the amount present changes.

There are many different properties that can be observed. The following are some examples.

Viscosity (intensive)
Viscosity is the tendency of a liquid to keep from flowing—its resistance to flowing.

viscosity
the degree to which something is thick, sticky, and semifluid in consistency, due to internal friction.

a quantity expressing the magnitude of internal friction, as measured by the force per unit area resisting a flow in which parallel layers unit distance apart have unit speed relative to one another.

One way to think about viscosity is to consider how "thick" a liquid is. Syrup is MORE viscous than water is.

The viscosity of a liquid usually decreases as its temperature goes up.

Conductivity (intensive)
Conductivity is the term used to express how well a material allows heat or electricity to flow.

conductivity
the degree to which a specified material conducts electricity, calculated as the ratio of the current density in the material to the electric field that causes the flow of current. It is the reciprocal of the resistivity.

(also thermal conductivity) the rate at which heat passes through a specified material, expressed as the amount of heat that flows per unit time through a unit area with a temperature gradient of one degree per unit distance.

Materials that have high conductivity, such as metals, are called conductors.

Hardness (intensive)
Hardness of a material relates to the degree to which its surface can be penetrated. For an object to scratch another object, it must be made of a material that has more hardness then the other.

hardness
a measure of how resistant solid matter is to various kinds of permanent shape change (such as bending, denting, and scratching) when a compressive force is applied.

Malleability (intensive)

Malleability is the ability of a solid to be hammered without shattering.

malleable
(of a metal or other material) able to be hammered or pressed permanently out of shape without breaking or cracking.

Most metals malleable to a greater degree than are other things, like ice or glass.

Ductility (intensive)

The degree to which a substance can elongate when pulled.

Examples: Chewing gum is very ductile. You can pull it and stretch it really far out of your mouth (although that is gross and germy). Carrots are not, compared to gum, very ductile. They snap off.

Flexibility (intensive)

Flexibility refers to how bendable something is. The more bendable something is the more flexible it is. If matter is not bendable then we call it rigid. Glass is rigid, and will break if you try to bend it too hard.

Elasticity (intensive)
Elasticity is the ability of an object or material to resume its normal shape after being stretched or compressed; sketchiness.

Melting and Boiling Points (intensive)
The melting point is the temperature at which a substance changes from solid to liquid. This same temperature is also the point at which the substance changes from a liquid to solid (freezing point).

The boiling point is the temperature at which a substance changes from a liquid to a gas. At this same temperature, gases condense into a liquid (condensation point).

Density (intensive)
Density is the ratio of a substance's mass to its volume and can be expressed mathematically as…

D=M/V

where D is the density, M is the mass, and V is the volume of the sample.

Density results from the number of protons, neutrons, and electrons in the atoms that make up the substances and how closely they are arranged to each other either in the substance.

Appearance (intensive)
How does it look? What is visually identifiable about the substance?

Some aspects of a physical appearance include its color, texture, or sheen. Uniformity of these things could also be a factor, or variances might indicate that the sample has some impurities in it.

Odor (intensive)

IMPORTANT NOTE: Don't sniff chemicals! You could die!

While it is dangerous to inhale chemicals, some of them do stimulate the olfactory nerves which results in the perception of odor.

Solubility (intensive)

Solubility is the degree to which a substance (solute) dissolves in a given solvent (other substance). Not everything dissolves in everything! There is a vast degree of variance in what will dissolve in what and to what degree! You need only watch a few TV commercials to know that Brand A dish soap will dissolve grease better than all the other! Let's just skip the laundry ads!

Solubility for a given substance might be noted in relationship to various solvents. How well does it dissolve in water? How about alcohol? How about mineral spirits? How about acetone?

Nail polish is a very intuitive example. Nail polish does not dissolve very well if at all in water. (If it did, it would come off with every hand wash!) It does, however dissolve readily in acetone (nail polish removers often are acetone).

Magnetivity / Magnetism (intensive*)

The degree to which a substance is attracted to or repelled by magnets and magnetic fields. Basically, do magnets stick to it or does it stick to iron?

*Larger samples of a magnetic substance will create a larger (i.e. stronger) magnetic pull, but the property is uniform regardless of sample size)

Specific Heat (intensive)

The capacity of a substance to hold energy in the form of heat.

If you have a dishwasher and have ever tried to unload it right after it was done, you know that the glass bowls will burn your fingers more than the plastic ones, but when the door opens, they are all the same temperature. Glass can hold heat better than plastic. Thus, the specific heat of glass is higher than the specific heat of plastic.

Specific heat is measured in a unit of energy per a unit of mass such as cal/gr or J/gr.

Opacity (intensive)

The capacity of a substance to block (usually limited to visible light) electromagnetic waves. Opacity ranges from transparent (light passes without diffusion), to translucent (some light passes but is diffused) to opaque (no light passes through).

While opacity is frequently used to discuss visible light, the same term applies to other types of radiation as well.

Mass (extensive)

The total amount of matter present, the sum of all the electrons, protons, and neutrons within the sample.

Volume (extensive)

The total amount of space occupied by the sample.

Density (intensive)

(D) is an intensive property of matter that is the ratio of mass (m) to volume (V) found by:

D = m/V

### What are Properties of Matter?

Where are we going with this?
The point of this deck is to give the background information and examples so that we can differentiate between substances (pure and mixtures) based on physical and chemical properties.

What are Properties of Matter?

Well, let's go with this: Properties of matter are the traits that can be observed, measured, or detected that are specific to different types of matter.

There are two two ways to categorize properties of matter.

The first way to categorize properties is to determine if they are intensive or extensive.

The second way to categorize properties of matter is to determine if they are physical properties or chemical properties. What does that even mean?

EXAMPLES

Mass is an extensive physical property.

Density is an intensive physical property.

Flammability is an intensive chemical property.