LAB: ELEMENTS AND THEIR PROPERTIES



ELEMENTS AND THEIR PROPERTIES Name __________________________

Throughout the ages of history, philosophers and scientists have talked about “the elements.” Reference to elements is most frequent today in the field of chemistry. What is a chemical element?

In this lab, you will be given samples of several common chemical elements: iron, magnesium, silicon, sulfur, and zinc. You will investigate the properties of these elements. By observing common properties, you will gain an insight into how an organizational chart can be created for all the known elements.

Read and understand the entire lab. What are the safety concerns in this lab?

MATERIALS

Samples of elements listed below Electrical conductivity tester Steel wool

Hydrochloric acid (HCl) Safety goggles 5 index cards

4 test tubes test tube rack Labeling tape

SAFETY

Goggles must be worn at all times. Wear gloves when handling hydrochloric acid. Skin and clothing should not come in contact with hydrochloric acid. If so, rinse clothing with water and wash skin immediately with soap and water.

PROCEDURES

1. Use labeling tape to label each of the test tubes with one of the 4 names of the chemical elements listed in the data table below except sulfur. You will use these test tubes in step #5.

2. Obtain the supplies:

1 large piece of sulfur

1 large piece of silicon, and 1 very small piece

1 iron wire

1 large piece of zinc, and 1 very small piece

1 long section of magnesium ribbon, and 1 very small piece

3. One of the physical properties of elements is the ability to conduct electric current. Touch the terminals of the electrical conductivity tester to either side of the large piece of each element. If the light on the tester goes on, that means an electric current is passing through both the light bulb and the sample of the element. It is important to make sure the part of the apparatus touching the elements stays dry and is not contaminated by any of the other elements it has been in contact with. Also, use steel wool to clean and polish the metal strips before you test them. Test the samples of each element with the conductivity testers and record whether they conduct electric current (yes) or not

(no). Record this data in the data table.

4. A metal is generally a solid that is shiny, malleable (bendable), and a good conductor of heat and electricity. A nonmetal is generally dull, brittle, and a poor conductor of heat and electricity. Looking at the large pieces, classify each of the elements as either a metal or a nonmetal and record in the data table.

5. A chemical property of elements is how it reacts with acid. Add about 1 ml (1 pipet full) of the hydrochloric acid (HCl) to each test tube. Add one small piece of each element (except sulfur) to the appropriate test tube. It is important to add the HCl to the test tube first so that you will not be surprised by a reaction.

6. Test a sample of each element for their reaction with HCl and record whether it reacts (yes or no) and, if so, what happens when they react. Record how it feels to the touch in addition to what you see.

7. For those that do react, try to determine whether all exhibit the same type of reaction and compare the rigor of the reactions. If the reaction is rigorous, include a + sign next to your “yes”. If the reaction is weak, place a – sign next to your “yes”.

Dispose of the test tube contents in the appropriate disposal container. Rinse the test tubes three times each with running water and place them upside down in the test tube rack to dry. Be sure to also wash your hands.

ANALYSIS

|Element |Initial observations |Conducts |Metal or non-metal |Reacts with acid |

| | |Electricity | | |

|Iron | | | | |

| | | | | |

|Magnesium | | | | |

| | | | | |

|Silicon | | | | |

| | | | | |

|Sulfur | | | | |

| | | | | |

|Zinc | | | | |

| | | | | |

1. Make an index card for each element and find a way to sort them based on their properties. You may try arranging them and/or color- coding them. Your method of sorting will be successful if you can quickly find an element and know from its position whether it:

a. Conducts electricity

b. Reacts with HCl

c. Is metallic or nonmetallic

2. Record the method by which your sorted the index cards.

3. Make a list of three or more physical properties of a chemical element that can be observed.

4. Make a list of chemical properties of a chemical element that can be measured.

5. Why did you want the metals to be clean or polished before you tested them for electrical conductivity?

6. What criteria did you use to differentiate metals from nonmetals in this lab?

7. Is this a valid statement of a trend you saw: As the elements become shinier, they are more metallic? Support your assessment of this statement with evidence you observed in the activity.

8. Is this a valid statement of a trend you saw: The elements react with HCl more if they are more metallic? Support your assessment of this statement with evidence you observed in the activity.

CONCLUSION

9. Answer the original question for the lab. Also, answer the question, why do different elements have different properties? Include supporting data in your conclusion and explain the answer thoroughly.

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