Elements and Compounds

Transcription

1 Chemistry Name: Partners: Date: Elements and Compounds Introduction Most of the materials you have used so far in this course were mixtures. If you could take them apart physically, you would find that they are made of two or more other substances. Some are compounds, which are also made of two or more substances, but they cannot be taken apart physically they can only be separated using chemical reactions. When you take something apart completely so that it cannot be separated further either chemically or physically, you have an element. In ancient Greece, the famous philosopher Aristotle stated that there were four elements : Earth, Wing, Fire, and Water. By the late 18 th Century (1700s), scientists knew that these weren t really elements, and had identified about elements, such as gold, silver, copper, and iron. Using early electricity experiments, they separated water into two invisible gases oxygen and hydrogen (whose name means coming from water. ) During the early 19 th Century (1800s), chemistry really began to develop into a mature science. Chemists used electricity, heat, and acids to separate rocks and minerals into their compounds and elements. By the middle of the 19 th Century, about 70 elements were known. Later in this course, you ll learn more about how two chemists, Dmitri Mendeleev and Henry Moseley, organized these into a chart called the Periodic Table of the Elements. You ll also learn how people later discovered all 92 natural elements and have created more than 23 synthetic elements in laboratories. In this activity, you will have the opportunity to examine representative samples of minerals and rocks to learn more about elements and compounds. Minerals are naturally-occurring solids that combine to make rocks, which are mostly mixtures. Most of these are inorganic substances. But you will also look at some examples of organic materials to identify the compounds and elements that compose them.

2 Chemistry Elements and Compounds, p. 2 Procedure 1) Examine the samples provided and complete the Observation Table on the other sheet. You should use your textbook, Properties of Common Minerals and Other Materials (below), and other resources to learn as much as possible about the materials. 2) There are three blank rows at the end. Find out about three other elements or compounds, and complete the cells in these rows When you finish attach the sheet to these guide sheets. 3) Answer the questions at the end of the information table. Properties of Common Minerals and Other Materials Name Composition Characteristics Uses Aluminum Al silvery metal, low density buildings, foil, many others Biotite mica K(Mg,Fe) 3 AlSi 3 O 10 (OH) 2 dark thin sheets electrical insulator Calcite CaCO 3 rhombic crystals cement, prisms or massive Candle wax C 17 H 35 O 2 soft, easily flames Copper Cu brassy-yellow electric wires, many others Feldspar KAlSi 3 O 8 pinkish mineral common in many rocks, ceramics Graphite C lead gray pencils Hematite Fe 2 O 3 reddish-brown ore of iron Magnetite Fe 3 O 4 black or silvery, ore of iron dense Malachite Cu 2 (CO 3 )(OH) 2 green ore of copper, jewelry Marble (a rock) CaCO 3 white or streaked rock buildings and other structures Muscovite mica KAl 3 Si 3 O 10 (OH) 2 light thin sheets electrical insulator

3 Chemistry Elements and Compounds, p. 3 Quartz SiO 2 colorless or variable most common mineral Pyrite FeS 2 brassy-yellow ore of iron Silicon Si shiny dark solid Sugar C 12 H 22 O 11 white, crystalline major body energy source Sulfur S yellow brimstone Zinc Zn silvery rough solid important metal Zincite ZnO orange-yellow ore of zinc Questions 1. Which of these substances are elements? 2. Which of these substances are compounds made of two elements? 3. Which of these substances are compounds made of three or more elements? 4. Which two are organic? 5. What produces the various colors in quartz? 6. Name any five substances that are gases, and tell if it is an element or compound. 7. The only liquid you examined is water. Use your references to find the names of the two elements that are liquid at room temperatures.

4 Chemistry Elements and Compounds, p. 4 Observation Table Name sample element(s) that characteristics and/or other number compose it comments Sulfur Copper Silicon Aluminum Zinc Quartz Feldspar Biotite mica Muscovite mica Calcite Marble Graphite Hematite Magnetite Malachite Zincite Pyrite

5 Chemistry Elements and Compounds, p. 5 Observation Table, cont d. Name sample element(s) that characteristics and/or other number compose it comments Sugar Candle wax Water