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Here are some links to activities involving measurement

By Joanne Moore,2014-04-16 21:34
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Here are some links to activities involving measurement

Lets Break It Lets Break It

    Down Down

    Periodic Table Periodic Table

    Legend

    Solid Liquid Gas Synthetic Alkali metals Alkali earth metals Transition metals Rare earth metals Other metals Noble gases Halogens Other nonmetals

    http://www-tech.mit.edu/Chemicool/

    WHAT IS AN ELEMENT? WHAT IS AN ELEMENT?

    ; An element is the most basic type of ; An element is the most basic type of

    chemical substance. All the elements known chemical substance. All the elements known

    to exist are listed in the periodic table. Some to exist are listed in the periodic table. Some

    elements are naturally occurring (oxygen, for elements are naturally occurring (oxygen, for

    example), while others are synthetically example), while others are synthetically

    produced (like einsteinium, named for Albert produced (like einsteinium, named for Albert

    Einstein). Einstein).

    ; If you were to split an element (like a block ; If you were to split an element (like a block

    of silver) into smaller and smaller pieces, the of silver) into smaller and smaller pieces, the

    smallest piece of that element that would still smallest piece of that element that would still

    retain its unique characteristics would be an retain its unique characteristics would be an

    atom. atom.

    ; Gold, silver, copper and many other metals ; Gold, silver, copper and many other metals

    are also elements. There are millions of are also elements. There are millions of

    atoms in a single gold ring! atoms in a single gold ring!

    NOW LETS THINK ABOUT COMPOUNDS NOW LETS THINK ABOUT COMPOUNDS

    AND MIXTURES AND MIXTURES

    ; A compound is a substance made up of two ; A compound is a substance made up of two

    or more elements connected by chemical or more elements connected by chemical

    bonds. For example: bonds. For example:

    This compound consists of This compound consists of

    Water Hydrogen and oxygen Water Hydrogen and oxygen

    Baking soda Carbon, hydrogen, oxygen, sodium Baking soda Carbon, hydrogen, oxygen, sodium

    Table salt Sodium and chlorine Table salt Sodium and chlorine

    Carbon dioxide Carbon and oxygen Carbon dioxide Carbon and oxygen

    ; A mixture is a combination of two or more ; A mixture is a combination of two or more

    elements or compounds that are not elements or compounds that are not

    chemically combined. chemically combined.

    ; Mixtures keep their physical properties and ; Mixtures keep their physical properties and

    can be physically separated. can be physically separated.

    ; An alloy is a mixture of two metals which, ; An alloy is a mixture of two metals which,

    when heated to extremely high temperatures, when heated to extremely high temperatures,

    actually dissolve into each other. actually dissolve into each other.

Objectives: Objectives:

    ; Examine each sample closely. Take note of ; Examine each sample closely. Take note of

    the samples color, texture, or other the samples color, texture, or other

    characteristics. DO NOT smell or taste the characteristics. DO NOT smell or taste the

    samples! samples!

    ; Record your observations on your worksheet. ; Record your observations on your worksheet.

    If you think you know the identity of the If you think you know the identity of the

    sample, jot it down in the observation sample, jot it down in the observation

    column. column.

    ; Decide whether each sample is a pure ; Decide whether each sample is a pure

    element, a compound, or a mixture. Mark element, a compound, or a mixture. Mark

    your answer in the second column on your your answer in the second column on your

    worksheet. worksheet.

     Name:____________________ Name:____________________

    Period:____________________ Period:____________________

    Write down your observations of the Do you think the sample is an Write down your observations of the Do you think the sample is an following samples: element, compound, or mixture? following samples: element, compound, or mixture?

A. A.

B. B.

C. C.

D. D.

E. E.

F. F.

G. G.

Lets break it down: Teachers notes Lets break it down: Teachers notes

Exercise written by Rachel Wooley, Undergraduate fellow.

     Prepare:

    ; A tightly-sealed jar of colored water and oil

    ; A tightly-sealed jar of water in which a tablespoon of table salt has

    been dissolved

    ; A block of brass

    ; A tightly-sealed jar of sugar cubes

    ; A small bowl of sand

    ; Aluminum foil*

    ; A tightly-sealed jar of cola

    *Aluminum foil designed for kitchen use are usually made of aluminum and <1% of other metals. Aluminum foil designed for medical or electrical use is often 100% pure aluminum. If you would like to use pure elemental aluminum but cannot find pure foil, pure aluminum wire is a good substitute. This could also be grounds for an interesting classroom discussion how pure are “pure” elements? Most pure substances are

    susceptible to contamination, oxidation, etc.

     Create seven stations around the classroom and place one of the above samples at each station. You can modify the difficulty of the exercise by choosing whether or not you wish to label each sample, some samples, or none at all.

    Most samples should be fairly simple to identify, but a few more challenging ones demonstrate that differentiation between compounds, mixtures, and elements cannot always be accomplished simply by sight.

    Students will visit each station and fill in their worksheets. After all (or most) students have completed the activity, discuss the correct answers.

     Ask students how they might separate various mixtures. The salt water mixture could be separated by evaporating the water and recollecting it as it rose and cooled. When you open a bottle of cola, you allow carbon dioxide to escape from the mixture. You can separate heterogeneous mixtures, too. For example, you could separate rocks from sand by passing the mixture through a sifter.

Notes concerning each of the seven compounds:

    The colored water and oil sample: This sample is a mixture. Oil and water are two different

    compounds which do not chemically combine. Because the oil and water are not evenly distributed throughout the mixture, it is a heterogeneous mixture.

    The salt water sample: This sample is a special type of homogenous mixture a solution. A

    solution describes a mixture in which one compound is dissolved into another. The salt is the “solute” and the water is the “solvent.”

    The brass sample: Brass is also a homogenous mixture. It may look like an element, but it is

    actually a mixture of two elements zinc (Zn) and copper (Cu). The metals are heated to extremely high temperatures and actually dissolve into each other. This process makes a type of mixture we

    call an “alloy.” Brass, steel, and bronze are common alloys. Pennies, dimes, nickels, and quarters are all made of alloys. A lab in which students create an alloy can be found here: http://matse1.mse.uiuc.edu/~tw/metals/g.html.

    The sugar sample: Table sugar, or sucrose, is a compound CHO. 122211

    The sand sample: If the sample is pure sand, or silicon dioxide, it is considered a compound.

    However, much of the sand or dirt found outdoors is a mixture of substances such as sand, humus,

    leaves, bugs, and clay.

    The aluminum foil: Aluminum is element #13. (Aluminum foils designed for kitchen use contain <1% of another metal, and thus are not purely elemental.)

    The cola sample: Cola is a mixture of many compounds. Common ingredients include fructose and carbon dioxide. This link will take you to an activity in which students separate various components from cherry cola: http://www.chemheritage.org/classroom/pharm/tg/chemo/activity/sep.htm.

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