Learning Objectives

Define element.State basic properties of an element.Give examples of elements and also their uses.

You are watching: Which substance can be decomposed by a chemical change?


Who is Sherlock Holmes?

Who is Sherlock Holmes?

The famed fictional brothers detective Sherlock Holmes was often said to make the declare “elementary, my dear Watson.” In reality, the closest that ever came to that line was an exchange with Watson in the brief story “The Crooked Man.” Holmes mirrors shrewd understanding into Watson’s tasks of the day. When asked just how he knew what Watson to be doing, Holmes just replies “Elementary.” regardless of precisely how he put it, Sherlock was just referring to what the free Dictionary defines as “relating to, or constituting the basic, essential, or fundamental part.”


Elements

An element is the simplest form of matter that has actually a unique set of properties. Instances of well-known elements include oxygen, iron, and gold (see the number below). Facets cannot be broken down right into a easier substance. Likewise, one element cannot it is in chemically converted into a different element.


Figure 2.14

Chemical facets are the most basic of substances. (A) an oxygen tank like this is used by world with a need for breath assistance. (B) A straightforward skillet have the right to be made from cast iron. (C) yellow bars are formed and also used for monetary purposes.


Some facets have been recognized for centuries (gold, silver, iron, copper, amongst others) while others have actually been developed in the lab just within the last numerous years. Most facets do not exist therefore in nature. They room so reactive the they have the right to be found only in mix with various other materials.

Several the the aspects are very an important while others are rather inexpensive. Gold is at this time worth almost $1700 every ounce. Aluminum, on the various other hand, just sells for around 90 cents per pound, substantially lower than gold. Copper is worth rather more, offering for about $3.50 pound. Platinum is very beneficial at around $1650 one ounce, not fairly as expensive as gold.

Enjoy an old song about the aspects sung through Harvard lecturer Tom Lehrer. Over there were only 102 known facets at the moment he wrote this song.


Summary

An element is the simplest type of issue that has a unique collection of properties.One element cannot be chemically convert to an additional element.

Practice

Questions

Select an element from this list:

http://www.lenntech.com/periodic/name/alphabetic.htm

Answer the following questions:

What is the surname of the element?When was it discovered?Who discovered it?What is one use for this element?

Review

Questions

What is an element?How much is yellow worth today?How many aspects did us know around when Tom Lehrer composed his song?

Glossary


element: The simplest kind of matter that has a unique collection of properties.
Compounds

Learning Objectives

Define compound distinguish in between element and compound.Give instances of compounds.Define chemical change.

What execute you have to start building a house?

What carry out you should start structure a house?

When structure a house, you start with a blueprint that what the house will look like. The plan states how numerous windows and what kind, how plenty of doors and what style, how plenty of rooms and also what kind (bedroom, kitchen, other). The blueprint shows how the different pieces will certainly go together to do the house. As long as the blueprint is followed and also exactly the same items room used, the residences will it is in identical.


Compounds

A compound is a problem that has two or an ext elements chemically an unified in a solved proportion. The elements carbon and also hydrogen incorporate to kind many various compounds. Among the simplest is referred to as methane, in which there are constantly four times as countless hydrogen particles together carbon particles. Methane is a pure substance because it constantly has the exact same composition. However, the is no an facet because it have the right to be broken down into simpler substances – carbon and hydrogen.

Recall that the components of a mixture deserve to be separated from one another by physics means. This is not true for a compound. Table salt is a compound consisting the equal parts of the facets sodium and chlorine. Salt can not be separated into its two facets by filtering, distillation, or any other physical process. Salt and other compounds have the right to only it is in decomposed right into their aspects by a chemical process. A chemical readjust is a readjust that produces matter with a different composition. Plenty of compounds deserve to be decomposed right into their aspects by heating. Once sugar is heated, the decomposes to carbon and also water. Water is quiet a compound, however one which can not be broken down right into hydrogen and oxygen by heating. Instead, the passage of an electrical present through water will develop hydrogen and oxygen gases.

The properties of compounds space generally an extremely different than the properties of the facets from which the link is formed. Sodium is really reactive soft metal that cannot be exposed come air or water. Chlorine is a deadly gas. The compound salt chloride is a white solid i beg your pardon is necessary for every living things ( Figure below ).


Figure 2.15

(A) sodium is therefore reactive that it must be save on computer under oil. (B) Chlorine is a poison yellow-green gas. (C) Salt crystals, a compound of sodium and also chlorine


Summary

A compound is a substance that includes two or an ext elements chemically linked in a addressed proportion.A chemical change is a adjust that produces matter with a different composition.

Practice

Questions

Watch the video clip at the link listed below to prize the complying with questions:

What lists all the elements we understand about?What is the compound made out of 2 hydrogen atoms and also one oxygen atom?What is the compound made the end of one carbon atom and two oxygen atoms?

Review

Questions

What is a compound?How is a compound various from an element?What is a chemistry change?
chemical change: A readjust that produces issue with a various composition.compound: A problem that has two or much more elements chemically merged in a addressed proportion.

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References

(A) Leon Brocard (Flickr: acme); (B) User:Evan-Amos/Wikimedia Commons; (C) Agnico-Eagle Mines Limited. (A) http://www.flickr.com/photos/acme/8532536/; (B) http://commons.wikimedia.org/wiki/File:Cast-Iron-Pan.jpg; (C) http://commons.wikimedia.org/wiki/File:Gold_Bars.jpg .(A) Hi-Res pictures of chemistry Elements; (B) User:Greenhorn1/Wikimedia Commons; (C) User:Miansari66/Wikimedia Commons. (A) http://images-of-elements.com/sodium.php; (B) http://commons.wikimedia.org/wiki/File:Chlorine2.jpg; (C) http://commons.wikimedia.org/wiki/File:Salt_,_Lake_salt.JPG .