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7th Grade Matter and Its Properties

20150916

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Table of Contents: Matter and Its Properties

Click on the topic to go to that section• What is Matter?

• The Simplest Form of Matter: • Elements of the Periodic Table

• States of Matter: A Physical Property

• Properties of Matter: Physical Properties

• Changes of State

• How Do We Measure Matter?

• Density: A Physical Property

• Properties of Matter: Chemical Properties

What is Matter?

Return to Tableof Contents

Chemistry is the study of matter, its properties and the changes it can undergo.

We have defined matter many times in your science classes.

Discuss with your classmates and define matter in your own words.

Matter and Chemistry?

Look around the classroom. Can you identify any examples of matter?

Where did it all come from?

Does all the "stuff" work with the definition you came up with?

Matter

What Are Atoms?All the matter in the universe is composed of basic building blocks

called atoms.

An atom is the smallest indivisible and indestructable unit of matter.

If you made a tiny dot with the tip of a sharp graphite pencil, that little dot would have about

four billion billion carbon atoms in it.

Atoms are really small!

What Are Atoms?Atoms are the basic unit of matter.

How are atoms like legos? Discuss with your classmates?

What Are Atoms?Atoms are the basic units of matter and indivisible.

You can break the lego house into individual lego pieces, but individual legos cannot be broken down further and still be

functional legos.

Similiarly, matter can be broken down into atoms, but atoms cannot be further divided and maintain their properties and function.

Atoms and ElementsLike the lego house below is made up of different types of legos, matter is made up of different types of atoms called elements.

Amazingly, all of the matter in the Universe is made up of only around 100 different elements in various combinations.

Almost 99% of the human body is made up of just 6 different elements!

Atoms and Elements

Gold Silver

Graphite(Carbon)

Neon Gas

Remember, one tiny dot of this contains about 4 billion billion atoms of the element carbon.

Elements are pure substances made from only one type of atom.

Atoms and ElementsSome pure substances, called compounds, are made up of

combinations of different types of elements.

Water Salt Chalk Bronze

Elements: hydrogen & oxygen

Elements: sodium & chlorine

Elements: calcium, carbon & oxygen

Elements: copper & tin

1 Which of the following would NOT be classified as matter?

B water

C water vapor

D wood

E all are examples of matter

Answer

2 All matter is made up of individual units called _______.

A compounds

B atoms

C pure substances Answer

3 _______ are pure substances made up of one specific type of ______.

A atoms, element

B atoms, compound

C elements, compound

D elements, atom

Answer

Proton Positive Charge

Neutron Neutral Charge

Electron Negative Charge

The Makeup of Atoms

Atoms are made up of 3 parts, known as subatomic particles. Each particle has a different charge.

Memory tricks have been underlined for you!

How Did We Get the First Atoms?We have talked about the Big Bang in years past as well.Take a few minutes to review what you know about the Big Bang.Write down some ideas here.

How Did We Get the First Atoms?

When the Big Bang first happened, the universe was very hot.

(20,000,000,000,000,000,000,000,000,000* times hotter than our Sun!)

*That number is 20 octillion !

After a few minutes, it cooled down to the point that protons and neutrons were able to join together.

Click here to learn more!

How Did We Get the First Atoms?Soon after the Big Bang, these particles captured objects called electrons.

This is because opposite charges are attracted to each other.

When this happened, the first two elements (and consequently the first atoms) were formed.

Hydrogenand Helium

Does anyone have an idea what the first two elements formed were?

Hint: think about the periodic table. Move this box for the answer once you

have your idea.

Because you will need this information later, keep in mind this old phrase:

"Opposites Attract"

What this means is that, just like a magnet, the positive proton and the negative electron attract each other!

Proton Electron

Opposites Attract

The center of the atom is called the nucleus . Protons and neutrons are found there.

Electrons move around the nucleus in the electron shell.

The space between the nucleus and the electron shell is empty.

How are Atoms Arranged?

We now know that an atom is made up of protons, neutrons, and electrons... but how are these 3 particles arranged in the atom?

Let's imagine an atom filled the distance from New York to Ohio. That is about 1030km.

At this scale, the nucleus would only be about the length of a football field. A football field is only 100m.

Relative Size of Atomic Particles

A proton would be about the height of a three story apartment building! That is about 9m.

And an electron would be about the width of a blueberry. A blueberry is only 1cm.

What does that tell us about this drawing of an atom?Is it accurate?

Click here to watch a TedEd video on the size of an atom.

Proton

Neutron

Electron

Helium atom

ProtonElectron

Hydrogen atom

The First Two Elements

Pull the tab to the left for more information!We will go into more detail about the elements when we talk about

the Periodic Table.

HHydrogen1.00

HeHelium4.00

More Info.

4 Which subatomic particle has a neutral charge?

A ProtonB NeutronC Electron

Answer

5 Which of the following subatomic particles are found in the nucleus of an atom?

A ProtonB Neutron

C Electron

Answer

D Both A and B

6 Label the parts of the atom.A 1. Proton2. Electron3. Neutron

B 1. Electron2. Neutron3. Proton

C 1. Neutron2. Proton3. Electron

D 1. Electron2. Proton3. Neutron

Answer

How Do We Measure Matter?

We have previously defined the amount of matter or the amount of "stuff" as its mass.

Mass is measured in grams (g) or kilograms (kg). (1 kg = 1,000 g*)

"kilo" = 1,000

Many times we use the words weight and mass

interchangeably (or we use them to mean the same thing).

However, this is wrong!

Can you remember what the difference is between weight and mass? Talk about it with your

partner.

Weight vs Mass

Weight is the measure of the force of gravity on an object. Weight is measured in pounds

(lbs) or Newtons (N).

On Earth, all objects are attracted to the center of Earth

by the force of gravity.

The force of gravity can be more or less on the Moon or on other planets, depending on

their sizes.

Weight

On the other hand, the amount of matter (stuff) in an object does not change with the object's location.

While your weight (gravitational force) may change if you travel

to the moon, the mass (amount of "stuff") in your body does not change.

This is because the gravity on the moon is much less than it is on Earth.Why is this?

Therefore, the weight of an object changes with its location.

Weight vs Mass

7 A person's mass on Earth would be __________ when they go to the moon.

A more

B less

C the same

8 A person's weight on Earth will be ____________ compared to when they travel to the moon.

A more

B less

C the same

9 Objects weigh less on the moon than they do on Earth because the moon has less ___________.

A mass

B gravity

C both A & B are correct

D neither A nor B are correct

The amount of 'space' that matter occupies is called its volume. Volume is measured in milliliters (mL) and cubic centimeters (cm³).

1 milliliter (mL) = 1 cubic centimeter (cm3)

Volume

To find the volume of a regular, boxshaped object you can measure its sides and multiply its measurements:

Volume = (length) x (width) x (height)

Measurements have units so you also multiply the units.

Units = (cm) x (cm) x (cm) = cm³

Calculating Volume of Regular Objects

10 What is the volume of a solid which has a length of 8 cm, a width of 4 cm and a height of 2 cm?

er Volume = l x w x h

V = (8 cm)(4 cm)(2 cm)

V = 64 cm3

11 How many cubic meters of dirt would it take to fill in a swimming pool that measured 18 meters long, 6 meters wide and 2 meters deep?

A 216 m

B 26 cm

C 216 m3

To find the volume of an irregular object you will need a graduated cylinder.

Calculating Volume of Irregular Objects

Volume of the diamond

1. Pour water into a graduated cylinder. Record the amount of water.2. Place the object into graduated cylinder.3. Record measurement of water level after the object was submerged.4. Subtract original water level from ending water level.

To find the volume of this object:

Example:

The volume of the water was 30 mL. After dropping the diamond intothe graduated cylinder, the total volume increased to 46 mL.

46 mL 30 mL = 16 mL

The volume of the diamond is 16 mL.

Volume of the diamond

Calculating Volume of Irregular Objects

12 An irregular object is dropped into a graduated cylinder containing 30 mL of water. After the object is added, the water in the cylinder measures 55 mL. What is the volume of the irregular object?

A 85 mL

B 25 mL

C 25 cm

D 55 mL

Lab: Measuring Matter

In this lab, you will demonstrate your ability to measure the mass and volume of various objects. You will need to find the volume of both

regular and irregular objects!

The Simplest Form of Matter: Elements of the Periodic Table

The number of protons in an atom determines which element it is. In the 1800’s scientists discovered different elements have different

properties because they have different numbers of protons and electrons.

The Atomic Theory

++++ +++ +++++++

+ ++++++

Element: Lithium Element: Fluorine

Properties: pale yellow, reactive gas at room temperature

Properties: silvery reactive metal,solid at room temperature

In the mid1800s, a Russian chemist named Dmitri Mendeleev created his own version of the periodic table of elements by arranging the

elements based on their properties, or characteristics.

He noticed that in doing this, there was a noticeable pattern in the atomic mass or atomic weight of the elements.

The First Periodic Table of Elements

Modern Periodic Table of ElementsMendeleev's format of the periodic table was used until around 1913. At

this time Henry Moseley, a British scientist, discovered the way to measure the number of protons in an element.

Having this number made it easier to describe the atoms of each element. Soon after, the table was rearranged using this amount, known

as an element's atomic number.

The Periodic Table of ElementsThe table below lists every known element in the universe. They are listed left to right based on their atomic number.

Click here for a printable Periodic Table.

Nitrogen

14.007

1 Atomic Number

2 Element Symbol

Element Name

3 Atomic Mass

1 Atomic Number is the number of protons in one atom of the element.

2 Element Symbol is a 1 or 2letter symbol that represents the element.

3 Atomic mass is the average combined number of protons and neutrons.

Reading the Periodic Table

HydrogenMagnesium

IronSilicon

CarbonNitrogen

Oxygen

Chlorine

Helium

Most Common Elements in the Galaxy

How is the Table Arranged?

The current table is arranged into seven horizontal rows called periods.

The period number tells you the number of layers there are in the atom's electron shell.

Because the pattern of

properties repeats in every period, the elements in each group have

similar characteristics.

The Group number tells you the number of electrons in the atom's outermost shell. Ex: Elements in Group 17 have 7 electrons in their

outer shells. (For Groups 1318, you subtract "10")

The table is also arranged in 18 vertical columns called groups that are numbered from left to right.

How is the Table Arranged?

13 The periodic table is arranged in horizontal rows called:

A Columns

B Groups

C Periods

14 The current periodic table is arranged from left to right according to increasing atomic mass.

15 The periodic table is arranged in vertical columns called:

A Columns

B Groups

C Periods

16 The group number tells us the:

A Atomic number

B number of electron shells the atom uses

C number of outer electons the atom has

17 The period number tells us the:

A Atomic number

B number of electron shells the atom uses

C number of outer electrons the atom has

Activity: Build an Atom

"Build an atom out of protons, neutrons and electrons and see how the element, charge, and mass change."

Click the picture above to access the web activity.

Properties of Matter:Physical Properties

Every type of matter has two kinds of properties: physical and chemical.

A physical property is a characteristic that can been observed without changing the substance into a new one.

Physical properties include: hardness, texture, density, flexibility, color, the ability to dissolve, magnetism, melting point, boiling point and the

substance's physical state (solid/liquid/gas).

Physical Properties

List some physical properties of this brick wall.

Some physical properties of substances are unique. Therefore, these properties can be used to determine mystery objects.

Using Physical Properties to Identify Substances

Imagine if someone wanted to sell you this "gold" coin. You can use the known physical properties of gold in order to test

if the seller is telling you the truth.

We will be looking at the physical properties of various elements in the Periodic Table.

Physical Properties of ElementsElements of the same group are sometimes said to be in the same

family. This is because elements that are grouped together often have similar properties.

Below, the elements are grouped into their respective families.H1

Nonmetals

Alkali Metals

Alkaline Earth Metals

Transition Metals

Other Metals

Lanthanides

Actinides

Metalloids

Halogens

Noble Gases

Look around the room. How many objects do you see that are made of metal?

What are some physical properties of the metals you see? Make a list.

Metals

Remember: Physical properties include hardness, texture, flexibility, color, the ability to dissolve, magnetism and if the object is solid, liquid, or gas.

Metals are malleable which means they are able to be hammered or rolled into

flat sheets or shapes.

Some metals are attracted to magnets.

Properties of Metals

Metals are ductile so they are able to be pulled or stretched out into long wire.

Most metals are good conductors, so they transfer heat and electricity well.

Properties of Metals

The following slides will introduce the various families of the Periodic Table as well as list some general characteristics of

elements that are a part of each family.

Remember, elements of the same family have similar traits.

Click here for a blank printable Periodic Table of Elements.

Use the link below to print blank copies of periodic table to fill in and color as you discuss families.

Be sure to include a key on your paper.

Families of the Periodic Table

Alkali Metals Alkaline Earth Metals

React by losing 1 electron React by losing 2 electrons

Never found uncombined in nature

Most reactive metals 2nd most reactive metals

Sodium (Na) and Potassium (K)most important Alkali metals

Magnesium (Mg) and Calcium (Ca) most important

Alkaline Earth metals

Elements that are found in Group 1 are called Alkali Metals. Elements in Group 2 are called Alkaline Earth Metals.

Not only are their names similar, but their properties are as well:

Alkali Metals vs Alkaline Earth Metals

*We will be looking more at how elements react with each other in the 2nd Unit of this school year!

Do you notice anything similar about the names of the elements in these two groups?

18 Does malleability mean a metal can be hammered into a flat sheet?

19 Alkali Metals react with other elements by gaining one electron.

Transition Metals

Transition Metals are in Groups 3 through Group 12. Transition metals are less reactive than Groups 1 & 2. They are hard and shiny

and are usually good conductors of electricity.

Color and label this section.

LanthanidesLanthanides are actually a part of Period 6, but they are typically moved to the bottom of the Periodic Table to make it easier to read.

They are usually soft, malleable, shiny metals that have high conductivity.

They are mixed with other metals to make alloys; a mixture of a metal with at least one other element, usually another metal.

Actinides

Below the Lanthanides, you can find the Actinides, which are a part of Period 7.

Only four elements in the Actinides occur naturally on earth. They are Actinium, Thorium, Protactinium and Uranium. All other elements, heavier than uranium, were created artificially in labs. The nucleus of each of

these elements is unstable causing it to break apart.

"Other Metals" and MetalloidsSome of the elements in Groups 13 through 15 are metals. They are not

as reactive as the metals on the left side of the table.

Metalloids are elements that are similar to both metals and nonmetals. They are hard, brittle and can conduct electricity.

"Other Metals" are in gray. "Metalloids" are in olive green.

NonmetalsA nonmetal is an element whose properties are opposite of metals.

Most nonmetals are poor conductors of heat and electricity. Solid nonmetals are brittle (break easily) and dull.

Don't forget about Hydrogen (H)!

Halogens

The Halogen family (found in Group 17) is the most reactive nonmetal group. The elements in this group are dangerous to humans when

uncombined.

The physical properties of these elements vary some elements are solids, some are liquids and some are gases at room temperature!

Bromine a liquid Chlorine a colorless gas

Iodine a solid

Notice that all of the halogens end in ine!

The Noble GasesThe elements in Group 18 are known as Noble Gases. Noble gases do not gain, share or lose electrons, which means that

they do not react with other elements.

What do the names of all of the Noble Gases end in?

Xenon Neon Krypton

20 All of the elements in Group 18 will be a ____ at room temperature.

A Solid

B Liquid

C Gas Answ

21 A useful property of a metalloid is its ability to conduct electricity.

22 Noble gases react very easily with other elements.

False Answ

23 Where on the periodic table are the transition metals found?

A Far right

B Middle

C Far left

The Physical Properties mentioned on the previous slides apply to all pure substances. This includes both elements and compounds .

A compound is formed when two or more different elements join together, or "bond." For example: H2O is made up of Hydrogen

and Oxygen atoms.

Compounds

A molecule is the smallest possible part of a compound.

Just like an atom is the smallest possible part of an element, a molecule is the smallest possible part of a compound.

Molecules

This box is filled with the compound

"water."

Each individual part ofthis compound is calleda molecule of water.

MoleculesMolecules are formed when one or more atoms chemically bond

together.

Water is formed when 2 Hydrogen atoms and 1 Oxygen atom combine.

It is important to realize that when these two elements combine to form water, their properties change. Hydrogen and Oxygen on their own

are completely different than water.

2 Hydrogens

1 Oxygen

Molecules

The structure of molecules can range from two or more of the same atoms or two or more different atoms.

Ozone O3 Salt NaCl Glucose (Sugar) C6H12O6

Na ClO

Build a Molecule: Water

We know this is a compound because it includes more than just 1 atom. This is a compound because two different elements are combining.

What do the H and the O stand for in the chemical formula above?

H _______________________

O _______________________

Oftentimes in a chemical formula, you will see a small number after the element symbols. This number is called the subscript.

This number tells you how many atoms of each element there are in the compound. The number goes along with the element before it.

If there is no number, then there is one atom of that element.

How many H atoms are there? _____

How many O atoms are there? _____

H2OBuild a Molecule: Water

A molecule is represented by a chemical formula which shows the elements in the compound and the ratio of atoms in that specific

compound.

Carbon Dioxide: CO2

# of C atoms =

# of O atoms =

RATIO of Carbon to Oxygen:

Ratio of Atoms

24 What is the ratio of Carbon atoms to Hydrogen atoms in Propane (C3H8)?

25 What is the ratio of Nitrogen atoms to Hydrogen atoms in Ammonia (NH3)?

26 The ratio of carbonhydrogenoxygen atoms in glucose (C6H12O6) is 6:12:6.

Activity: Build a Molecule

"Starting from atoms, see how many molecules you can build. Collect your molecules and see them in 3D!"

Density: A PhysicalProperty

Demo: Density Column

Have you ever wondered what makes an object "sink"

or "float?"

Why does the red substance below float to the

top of the test tube? Why does the blue substance sink?

Density is a measure of how much mass is contained in a given volume.

Density is a measure of how much ‘stuff’ there is in an object,

and how tightly that ‘stuff’ is packed together.

To calculate for density, the following formula is used:

Density = Mass / Volume

D = M / V

Density

Mass is measured in grams (g) and volume may be measured in cubic centimeters (cm3). Therefore, one unit for density is grams

per cubic centimeters (g/cm3).

Units for Density

There are two different units for density:

We have already learned that volume can also be measured in milliliters (mL) and we know that 1 mL = 1 cm3.

Therefore, density can also be measured in grams per milliliter (g/mL).

27 Which of the following is a unit for density? Choose all that apply.

A Grams (g)B Grams per milliliter (g/mL)C Milliliters (mL)D Pounds (lbs)E Grams per cubic centimeter (g/cm3)F Cubic centimeters (cm3)G Kilograms (kg)

B and E

Density is a physical property of a substance. Each element and compound has a unique density.

Therefore, density can be used to identify an unknown substance.

The Density of Matter

The density of this mask is 19.3 g/cm3.

Copper 8.96 g/cm 3

Gold 19.3 g/cm 3

Bronze 7.7 g/cm 3

What is the mask made of?

The density of water is 1 g/cm3.

Objects with a density that is lower than water will float.

Objects with a density that is greater will sink.

Demo: Will it Float?

Predict whether each object will float or sink and answer the questions that follow this demonstration!

The formula for Density is mass/volume.

Density is expressed as grams per cubic centimeter (g/cm³).

Density =mass

volume

D = m/v

Calculating Density

28 What is the density of an object with a mass of 130 g and a volume of 8 mL?

29 What is the density of a piece of wood that has a mass of 25 g and a volume of 29.4 cm³?

30 A liquid has a volume of 5 mL and a mass of 20 grams. What is its density?

A 4 g/mlB 80 g/mLC 4 mL

31 A solid with a mass of 30 grams and a volume of 10 mL has a density of 3 g/mL.

Using algebra, the density formula can be rearranged to solve for

mass and volume:

mass = density x volume

M = DV

volume = mass / density

V = M/D

Variations of the Density Formula

32 An ice cube that measures 5.8 cm x 5.8 cm x 5.8 cm has a density of 0.917 g/cm3. What is its mass?

Volume = 5.8 cm x 5.8 cm x 5.8 cm = 195.112 cm3

M = DVM = (0.917 g/cm3) x (195.112 cm3)M = 179 g

33 The density of copper is about 9 g/cm³. What would the volume of a copper object be if its mass was 45g?

Demonstrations

Density Column Demo Will it Float Demo

These demonstrations will help in your understanding of density.

Lab: Determining Density

Now that we have learned how to calculate for density, you will use your skills to find the density of various objects and then determine whether each would sink or float in water!

States of Matter:A Physical Property

States of MatterAs mentioned before, we will study three different "states," or forms, of

matter in this unit:

Solid Liquid Gas

When you identify a substance as a solid, liquid or a gas, you are identifying one of its physical properties.

Which of the objects below do you think is easiest to hold in your hand?

Order from easiest (1) to hardest (3). Explain your choices.

The gas inside of this

balloon

The water of Niagara Falls

A solid rock

States of Matter

Solids have definite shape and definite volume. This means that a solid will not freely change what it looks like.

Look around the classroom and identify several objects that meet this criteria. Do those objects have a definite shape

and a definite volume?

Solids

The pencils to the left are solids. If left alone, they will maintain this

shape and size.

Look around the classroom and identify ten objects that meet this criteria and write them down here. This should be an easy task.

Solids

Do those objects have a definite shape and a definite volume?

The particles of a solid are strongly attracted to each other.

Solids will keep their shape because of this strong attraction.

The particles don't move past each other, but vibrate.

There are two types of solids: crystalline and amorphous.

Solids

The particles that make up crystalline solids are in a regular repeating pattern.

Crystalline solids have a distinct melting point.

Quartz Basic crystal shapes

Crystalline Solids

The particles of amorphous solids are NOT arranged in a regular pattern.

Amorphous solids do NOT have a distinct melting point (we will discuss melting point later in this unit).

Amorphous solids

34 What are the characteristics of a solid?

A Definite shape

B Definite color

C Definite volume

35 An object with a definite shape will also always have a definite volume.

36 In which type of solid do the particles form a regular, repeating pattern?

A Crystalline

B Amorphous

37 Amorphous solids melt at a distinct temperature.

The particles of a liquid are attracted to each other, but move more freely than the particles of a solid. Because of this, they are also referred

to as fluids.

Unlike in a solid, the particles of a liquid are able to move past

one another.

Liquids

Because the particles move freely around, a liquid has no definite shape.

A liquid has a definite volume but NOT a definite shape.

Characteristics of a Liquid

The particles that make up a liquid have more energy than the particles in a solid. This causes them to move around quicker and keeps them

from maintaining a definite shape.

This concept can be confusing so we will look at an example:

First, a student fills this bottle with water.

Then, the student then takes this bottle and pours all of the water into an empty pot.

In both situations, you have the same amount of water. However, because the bottle and the pot have different shapes, the shape of the

water is now different.

Liquids Further Explained

38 What are characteristics of liquids?

A No definite shape

B Definite color

C Definite volume

39 Liquids always take the shape of their containers.

40 A substance that can flow is called a ___.

A Liquid

B Fluid

When a substance is in the form of a gas, its particles are moving very quickly more

quickly than a solid or a liquid. Gas particles have more energy than solids and liquids.

Because of this, a gas changes its volume very easily.

As gas particles move, they will fill all of the space available to them, no matter how much space the gas took up before.

Gases have no definite shape and no definite volume.

An object that has the ability to flow freely.

Just like a liquid, the gas that fills the balloon is called a fluid.

What is a fluid? Come up with a definition with your partner.

Move this box for the answer.

41 A gas is considered to be a fluid.

42 A gas has a definite shape and a definite volume.

43 A gas can not change volume easily.

Activity: States of Matter

"Watch different types of molecules form a solid, liquid, or gas. Add or remove heat and watch the phase change!"

Changes of State

Changing States of Matter

Matter can freely change from one state (also known as "phase") to another. One of the most common ways for a phase change to occur is

by a change in temperature.

EnergyPreviously, we learned that the difference between solids, liquids and gases is the amount of energy in the particles, or atoms, that

make up the object.

Energy is tough to define, but in this case, we can say that it is the speed at which the atoms move throughout the object.

For example, more energy means that the particles are moving more and will be moving quicker.

At right, you can see an example of gas particles in motion.

The Energy of MatterDrag the objects below into the correct order based on the amount

of energy in the substances' atoms.

Least energy Most energy1 2 3

Applying the Heat

Raising the temperature of an object will cause its particles to move more and to speed up.

On the other hand, lowering the temperature will cause the particles to move less and to slow down.

Click on the picture above to see this in action.

Every change of state requires a change in energy. This change can only occur if energy is added or taken away.

Sometimes this energy can come from a change in pressure, but in this unit, we will focus on a change in heat.

Least heat Most heat1 2 3

Solid Liquid Gas

Change in Energy Change in State

Adding thermal energy to a solid increases the temperature of the object.

Increasing temperature causes the particles to move faster. When this happens, the rigid structure of the solid

starts to break apart.

The solid begins to change into a liquid.

Solid Liquid

The change in state from solid to liquid is called melting.

The melting point for ice is 32° Fahrenheit (0° Celsius). That is the temperature at which ice becomes water.

Melting

In most substances, melting happens at a specific temperature called the melting point. The melting point is different for all

objects.

If thermal energy is removed, the temperature of the object decreases.

Decreasing the temperature causes the particles to move slower. When this happens, the particles align in a rigid structure.

The liquid now begins to change into a solid.

Liquid Solid

The change of state from liquid to solid is called freezing. Freezing is the opposite of melting and, therefore, the

freezing and melting points are the same.

When you put liquid water in the freezer, the water loses energy to

the cold air in the freezer.

When the water temperature drops to 32° Fahrenheit (0° Celsius)

the water will freeze.

Freezing

44 Particles of a substance at a warmer temperature have more thermal energy than that same substance at a cooler temperature.

45 What happens to the particles of a liquid as they lose energy?

A The particles move at the same rate.

B The particles move slower.

C The particles move more rapidly. Answ

The change of state from a liquid to a gas is called vaporization.

Liquid Gas

Vaporization occurs when the particles in a liquid gain enough thermal energy to

form a gas.

There are two types of vaporization: evaporation and boiling.

Boiling occurs when liquid that is below the surface changes to a gas as a result of heating. For example, when water boils, its particles

bubble and the gas rises.

The temperature at which a substance boils is called its boiling point .

Every element and molecule has a unique boiling point, therefore it can help scientists identify unknown substances.

Boiling

Water boils at 100 o C (212o F).

Evaporation is vaporization that takes place slowly on the surface of a liquid.

Evaporation

It is this process that causes puddles or bodies of water (as seen here) to dry up.

The water gains energy from the ground, the air or the sun.

The added energy allows the water molecules on the surface

to evaporate.

The opposite of vaporization is condensation. When a gas condenses, it turns back into a liquid.

Condensation occurs when particles in a gas lose enough thermal energy to form a liquid.

Gas Liquid

46 The change of state from a liquid to a gas is called _________.

A condensationB sublimationC vaporization

47 During _____ water vaporizes only at the surface.

A evaporationB boilingC condensation

48 During ___, water vaporizes below the surface of a liquid.

A evaporation

B boiling

C condensation Answ

49 Chemists use boiling points to help identify unknown substances.

50 Water freezes at ______o C.

51 Water boils at ______o C.

100o C

LIQUID

Phase Change Review

vaporization freezing

condensation

melting

Drag and drop the terms next to the correct arrow.

You can use the melting and boiling points of substances to determine whether it would be a solid, liquid, or gas at a given temperature.

Solid, Liquid or Gas?

Solid Liquid Gas

Let's use water as an example:

The melting point (which is also the freezing point) of

water is 0o C.

The boiling point (or condensation point) of

water is 100o C.

0o C 100o C

Freezing and Boiling Points

0o C 100o C

If the water is below the freezing point (in this case, less than 0o C) then it would be solid ice.

0o C 100o C

If the water is above the boiling point (in this case, more than 100o C) then it would be a gas.

0o C 100o C

If the water is between the boiling point and melting point (between 0o and 100o C) then it would be liquid water.

At room temperature (20o C) water will be a liquid.

52 Which of these temperatures would fit a sample of liquid water?

A 85o C

B 110o C

C 34o C

D 0 o C

53 Which of these temperatures would fit a sample of water vapor?

A 85o C

B 110o C

C 34o C

D 0 o C

CHLORINE

Plot and Label the following:

The melting point, (MP); the boiling point, (BP); and room temperature, (RT, 20°C).

Identify the states of matter of the substances at room temperature.

SubstanceGold

Chlorine

1064 2807100.98 34.6

Melting Point (oC) Boiling Point (oC) State of Matter

54 If aluminum's melting point is 660°C and its boiling point is 2519°C, identify its state of matter at room temperature.

A solid

B liquid

55 If flourine's melting point is 220°C and its boiling point is 188°C, what is it at room temperature?

A solid

B liquid

C gas Answ

56 Mercury has a melting point of 39°C. Its boiling point is 357°C. What state is mercury at room temperature?

A solid

B liquid

Properties of Matter:Chemical Properties

Chemical Properties We have spent some time discussing physical properties.

A chemical property is a characteristic of a pure substance that describes its ability to change into a new substance.

Chemical properties can only be observed if the matter undergoes a chemical reaction resulting in chemical change.

A chemical reaction between a metal and gas makes table salt.

Some chemical properties include flammability (or the ability to burn), the ability to rust , corrosion (or breaking down) and

reactivity (or the ability to bond with other substances).

Matches ignite when you strike them because of a mixture of two substances: phosphorus and potassium chlorate.

These substances are highly flammable, but you would not be able to tell until you lit them on fire!

Examples of Chemical Properties

A banana ripens and turns brown as a result of chemical reactions, therefore, ripening is a chemical change.

Examples of Chemical Properties

This one is trickier, so it's helpful to think about the properites of a banana before and after ripening. Fill in the characteristics below:

Before a banana ripens:color:texture:taste:

After a banana ripens:color:texture:taste:

Reactivity is the ease and speed with which an element is able to combine or react with another element.

Elements in Groups 1 and 7 are very reactive and elements in Group 8 will hardly ever react.

Reactivity of Elements

Physical vs Chemical Properties

Physical Properties Chemical Properties

sodium metal

chlorine gas

table salt

shiny, soft very reactive

very stable (does not react with other substances)

very reactive

57 Elements in group 8 are the most reactive.

True False

58 Attraction to magnets is a physical property.

59 The ability to corrode (or break down) is a physical property.

60 Which of the following is an example of a physical change, but not a chemical change?

A Ice melting into liquid water

B A candle burning

C An exposed metal pipe rusting

D An apple slice turning brown

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