Matter PESTL Content Course

Brett D. Moulding – InstructorNovember 8, 2008

1. Matter = An Overview2. Atomic Theory3. Conservation of Mass4. Chemical Equations5. What is a “Mole”6. Chemical and Physical Change7. Putting it all Together

We will be learning chemistry today

1. Chemistry is not easy – remember some important things as we work to understand chemistry.a) Learning is about making sense of things

and connecting it to what we already know of the natural world.

b) Big ideas should have examples tied to them.

c) We are in this together, we will build upon our collective experiences and develop new understanding.

d) Learning is half the fun of living!A good teacher must be able to put himself in the place of those who find learning hard.—Eliphas Levi

Matter an Overview

1. Classic Definition – Matter has mass and takes up space.

a) So what is the difference between mass and weight?

b) Is matter everything?c) What affects matter?

i. Energy (e.g., heat, light)ii. Pressureiii. Interaction with other matter

d) Matter Cycles

Atomic Theory

Five main points of Dalton's Atomic Theory1.Elements are made of tiny particles called atoms. 2.All atoms of a given element are identical. 3.The atoms of a given element are different from those of any other element; the atoms of different elements can be distinguished from one another by their respective relative weights. 4.Atoms of one element can combine with atoms of other elements to form chemical compounds; a given compound always has the same relative number of isotopes.5.Atoms cannot be created, divided into smaller particles, nor destroyed in the chemical process; a chemical reaction simply changes the way atoms are grouped together.

MATTER

Substances Mixtures

ELEMENTS COMPOUNDS Solutions Suspensions &

Mixtures

Atoms Molecules Elements and Compounds

Atoms Atoms Atoms and/or Molecules

Protons

Neutrons

Electrons

Protons

Neutrons

Electrons

Protons

Neutrons

Electrons

Protons

Neutrons

Electrons

Making Sense of Matter

Atomic Theory

Particles• Matter is made up of particles• Identity of atoms - Elements• Conservation of Atoms• Interaction of Atoms

Space between particles

Periodic Table of the Elements• Elements• Atomic Number • Identity• Patterns

Periodic Table of the Elements

How to use the Periodic Table

Elements are described on the periodic table. The number of protons in an atom defines the element.

For example, carbon atoms have six protons, hydrogen atoms have one, and oxygen atoms have eight.  The number of protons in an atom is referred to as the atomic number of that element. The number of protons in an atom also determines the chemical behavior of the element.

http://periodic.lanl.gov/default.htm

Periodic Table of the Elements online

Atomic SymbolThe international atomic symbol is one or two letters chosen to represent an element (“C" for carbon, “Fe” for iron).  Sometimes the symbol represents the Latin name of the element. Fe = iron = Ferrous, Sn = tin = Stannous

Atomic MassThe atomic mass is the average mass of an element in atomic mass units ("amu").  This is equal to the mass of 6.02 X 1023 particles of the element. This is referred to as a mole of the element.

Interesting sidebarIsotopes can have a weight either more or less than the average.  The average number of neutrons for an element can be found by subtracting the number of protons (atomic number) from the atomic mass. 

Atomic Symbol

C6

12.01

Mass NumberAtomic Number

Conservation of Matter

1. “In an ordinary chemical reaction matter is neither created nor destroyed.

2. Conservation of mass and identity of elements

3. Experimentsa) Rusting Nailb) Cream and Vinegar

Chemical Equations

1. Chemical equations represent a chemical reaction.

2. The equation indicates the chemical change.

3. The equation indicates the mass is conserved when balanced.

4. The equation may include energy changes.

Equations

Atoms and/or Molecules

= Atoms and/or Molecules

H2 O2 = H2O

Ag+ Cl- = AgCl

CO2 H2O = C6H12O6 O2

How molecules are symbolizedCl2 2Cl2

• Molecules may also have brackets to indicate numbers of atoms e.g., Ca(OH)2 O

HO

HCa

• Notice that the OH is a group• The 2 refers to both H and O• How many of each atom are in the following?

a) NaOHb) Ca(OH)2

c) 3Ca(OH)2

Na = 1, O = 1, H = 1Ca = 1, O = 2, H = 2Ca = 3, O = 6, H = 6

Balancing Equations: MgO• The law of conservation of mass states that matter

can neither be created nor destroyed.• So we are just moving the furniture in a chemical

reaction• The number of a particular atom is the same on both

sides of the chemical equation

Example: Magnesium + OxygenMg + O2 MgO

O Mg O+ Mg O

However, this is not balancedLeft: Mg = 1, O = 2Right: Mg = 1, O = 1

Balance equations by “inspection”

Hints: start with elements that occur in one compound on each side. Treat polyatomic ions that repeat as if they were a single entity.

52 22

2 63

a) P4 + O2 P4O10

b) Li + H2O H2 + LiOHc) Bi(NO3)3 + K2S Bi2S3 + KNO3

From Mg + O2 MgO 2Mg + O2 2MgO is correct

Mg + ½O2 MgO is incorrectMg2 + O2 2 MgO is incorrect

4Mg + 2O2 4 MgO is incorrect

Here are some more to balance:a) KNO3 KNO2 + O2

b) Pb(NO3)2 PbO + NO2 + O2

c) P4 + I2 PI3

d) MgO + H3PO4 Mg3(PO4)2 + H2O

e) Br2 + KI I2 + KBr

f) Ca(OH)2 + HNO3 Ca(NO3)2 + H2O

a) 2KNO3 2KNO2 + O2

b) 2Pb(NO3)2 2PbO + 4NO2 + O2

c) P4 + 6I2 4PI3

d) 3MgO + 2H3PO4 Mg3(PO4)2 + 3H2O

e) Br2 + 2KI I2 + 2KBr

f) Ca(OH)2 + 2HNO3 Ca(NO3)2 + 2H2O

Balanced

What is a “Mole”A dozen = 12 of anythingDozen is a way of counting things in bunches2 dozen eggs, 1 dozen donuts, or 3 dozen golf balls

• 1 dozen eggs has a mass • 1 dozen golf balls has a mass• 1 dozen donuts has a mass

A gross of pencils = 144 sheetsA ream of paper = 500 sheets

A mole = 6.02 X 1023 of anythingMole is a way of counting very small things in groups

• 1 mole of carbon has a mass of 12.01 grams• 1 mole of hydrogen has a mass of 1.01 grams• 1 mole of oxygen has a mass of 16.0 grams• 1 mole of water (H20) has a mass of 18.0 grams

What is a “Mole”

Lets do some math

• 1 ml of water = 1 gram of water• 1 mole of water = 18.0 grams of water• 1 mole = 6.02 X 1023 particles

•So, how many molecules of water in a bottle of water?• Bottle of water = 591 ml of water.

•591 ml H2O X 1 gram H2O X 1 mole H2O X 6.02X1023 molecules H2O = 1 ml H2O 18.0 grams H2O 1 mole H2O

So we have 2.0 X 1025 molecules in a bottle of water

250.000,000,000,000,000,000,000,000 molecules of water in a bottle of water.

Chemical and Physical Change

1. Chemical Properties2. Physical Properties3. Physical Change4. Chemical Change5. How do we know when a chemical change

has occurred?

Determine whether the following are chemical or physical changes

a. Tear a piece of paper (physical)

b. Strike a match (chemical)

c. Mix a small amount of salt with H2O (physical)

d. Fold aluminum foil to make a small pan and do the following in the pan:

i. Put a drop of H2O in the pan. (physical)

ii. Put a small amount of sugar in the pan and heat it. (chemical)

e. Add a small amount of vinegar to baking soda(chemical)

f. Put a small amount of cornstarch in your hand and add a few drops of H2O to form a dough (chemical)

Activity

1) Place two shiny nails in a small Ziploc snack bag

2) Add about 20 ml of vinegar3) Let both stand in the vinegar for 15-30 seconds4) Remove one of the nails and place in a dry

Ziploc snack bag5) Observe regularly over the next two days6) Compare the appearance of the two nails7) Describe your observations and make

warranted inferences and hypothesizes based on evidence

8) Predict what would happen if you used a galvanized nail

Preventing a chemical reaction

a. Obtain 2 large nails. Paint one nail and leave the other one unpainted.

b. Put both nails in a jar with water. Cover the jar and let it stand 3 days.

c. Compare the appearance of the nails (painted nail does not form rust).

Can you think of other examples of how we stop or slow chemical reactions?

Remove energy – Place in a refrigerator, take away sunlight

Take away the source of reactants – Prevent oxygen from getting to the nail and letting it rust

Replace one reaction with another – Zinc bar on a bridge or ship will prevent rusting

Qualitative Physical Property

A description of a properties of a substance that is not related to the amount of the substance present (e.g., density, color, texture). These are the intensive properties.

 

Quantitative Physical Property:

A numerical description of a substance specifically related to the amount of substance (e.g., mass, length). These are the extensive properties.

Chemical property:

A characteristic behaviour which occurs when one substance interacts with another substance to become a NEW substance. 

Chemical and Physical Properties

Chemical Property

A chemical property is any of a material's properties that becomes evident during 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 for its chemical properties to be investigated.

Chemical properties can be contrasted with physical properties, which can be discerned without changing the substance's structure.

Examples of Chemical Properties• Electronegativity • Ionization potential • pH balance • Reactivity against other chemical substances • Heat of combustion • Enthalpy of formation • Toxicity • Chemical stability in a given environment • Flammability • Preferred oxidation state(s) • Coordination number • Capability to undergo a certain set of transformations e.g.,

molecular dissociation, chemical combination, redox reactions under certain physical conditions in the presence of another chemical substance

• Preferred types of bonds to form, e.g., metallic, ionic, covalent

Physical Properties

A physical property is any aspect of an object or substance that can be measured or perceived without changing its identity. Physical properties can be intensive or extensive. An intensive property does not depend on the size or amount of matter in the object, while an extensive property does. In addition to extensiveness, properties can also be either isotropic, if their values do not depend on the direction of observation, or anisotropic otherwise. Physical properties are referred to as observables. It is not a modal property. Examples of physical properties are sublimation, odor, color, and shape.

Often, it is difficult to determine whether a given property is physical or chemical. Color, for example, can be "seen”; however, what we perceive as color is really an interpretation of the reflective properties of a surface. In this sense, many ostensibly physical properties are termed as supervenient. A supervenient property is one which is actual (for dependence on the reflective properties of a surface is not simply imagined), but is secondary to some underlying reality.

Examples of Physical PropertiesThe physical properties of an object include:

• absorption • acceleration • angle • area • capacitance • concentration • conductance • density • dielectric • displacement • ductility • distribution • efficacy • electric charge • electric current • electric field

• luminance • magnetic field • magnetic flux • mass • molality • moment • momentum • permeability • permittivity • power • pressure • radiance • solubility • luster • resistance • spin

• electric potential

• emission • energy • expansion • exposure • flow rate • fluidity • frequency • force • gravitation • impedance • inductance • intensity • irradiance • length • location

• strength • temperature • tension • thermal transf

er

• time • velocity • viscosity • volume

Physical Change

A physical change alters only the form or state of the substance. The chemical composition of the substance has not changed. Example:Melting ice or the evaporation of water. The water still has the same chemical compositions (H2O) regardless of its state.

Other Examples:

A chemical change causes substances (the reactants) to change into different substances (the products).The products will have different physical and chemical properties than the reactants.Examples: rusting nail. Rust has a different composition than nail and different properties – (Iron Oxide cannot be picked up by a magnet, Iron metal can be picked up by a magnet

Chemical Reaction

The process of chemical change is called a chemical reaction.

 Reactants Products

 Evidence that a chemical reaction has occurred includes:- Color change- New solid formed (precipitate)- New gas formed- Light produced-Heat released or absorbed

If the product exhibits one or more of these features a chemical change likely happened.

Chemical Change

Chemical Change –vs- Physical Change

•Chemical change = Chemical reactionA chemical change is a dissociation, recombination, or rearrangement of atoms.

•Physical change = A change which does not transform one substance into another. For example, freezing water is a physical change because both water and ice are H2O. However, electrolysis of water would not be a physical change because passing a strong electric current through water can decompose it into H2 and O2.

Reaction Types and Examples

Synthesis- heat 0.5g Fe filings and 0.5g Sulfur

Fe + S --> FeS

Decomposition- Burn some sugar in a test tube

C12H22O11 -->12C + 11H2O

Single replacement- Cover a piece of copper wire with silver nitrate solution.

Cu + AgNO3 --> CuNO3 + Ag

Double replacement-Add several drops of silver nitrate solution to salt water.(white ppt, AgCl, forms)

NaCl + AgNO3-->AgCl + NaNO3

Putting it all TogetherPC & CC

1. What does this all mean?2. How do we know when to end the story?3. Looking for these changes around us.

What is Important Knowledge

• Identify three essential concepts/skills that you want students to know and be able to do.

(write them down)

• Select one – circle• What evidence would you accept that

your students know or can do _____?

Chemistry in a Nutshell

• The AtomAll macroscopic matter is made out of many tiny particles called atoms.  The study of how these atoms interact is called Chemistry.  

• Subatomic ParticlesThe three particles that make up atoms are protons, neutrons, and electrons.   Protons and neutrons are heavier than electrons and reside in the "nucleus," which is the center of the atom. Protons have a positive electrical charge, and neutrons have no electrical charge.  Electrons are extremely lightweight and are negatively charged. They exist in a cloud that surrounds the atom. The electron cloud has a radius 10,000 times greater than the nucleus. 

• The NucleusThe nucleus of an atom is made up of protons and neutrons in a cluster.  Virtually all the mass of an atom resides in the nucleus.  The nucleus is held together by the tight pull of what is known to chemists and physicists as the "strong force."  This force between the protons and neutrons overcomes the repulsive electrical force that would, according to the rules of electricity, push the protons apart otherwise.

Chemistry in a Nutshell (continued)• Electrons 

The electron is the lightweight particle that "orbits" outside of the atomic nucleus. Chemical bonding is essentially the interaction of electrons from one atom with the electrons of another atom. The magnitude of the charge on an electron is equal to the charge on a proton.  Electrons surround the atom in pathways called orbitals.  The inner orbitals surrounding the atom are spherical but the outer orbitals are much more complicated. 

• Chemical BondingChemically bonding occurs when two particles can exchange or combine their outer electrons in such a way that is energetically favorable.  An energetically favorable state can be seen as analogous to the way a dropped rock has a natural tendency to fall to the floor. When two atoms are close to each other and their electrons are of the correct type, it is more energetically favorable for them to come together and share electrons (become "bonded") than it is for them to exist as individual, separate atoms. When the bond occurs, the atoms become a compound.

Chemistry in a Nutshell (continued)• Chemical Reactions

Chemical reaction re-arrange chemical bonds and atoms to form new substances. The elements are the same, the molecules are different. The change is associated with breaking or forming bonds that absorb or release energy in the form of heat, light and/or sound. In a chemical reaction the identity of the atoms and the mass of the atoms remains the same.

• Conservation of MatterIn an ordinatry chemical reaction, matter is neither created nor destroyed.

Web Links

• http://www.chem4kids.com/files/matter_intro.html • http://www.chem4kids.com/

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