Periods on the Periodic Table

Transcription

1 Minerals Chapter 2

2 Matter Matter includes anything that has mass and takes up space (volume). It exists in 3 main states on Earth solid, liquid, and gas. Matter can be classified based on its physical state, chemical composition & structure.

3 Elements Elements are the building blocks of minerals. Elements cannot be broken down into a simpler substance. 95 naturally occurring elements Organized based on properties in the Periodic Table of Elements

4 Periods on the Periodic Table The periods are the rows on the periodic table. Elements in the same period have the same number of energy levels in their electron cloud.

5 Groups on the Periodic Table The groups are the columns on the periodic table. Elements in the same group have similar properties. The groups are also called families.

6 Atoms Basic atomic structure

7 Compounds Compounds form when two or more elements combine making a substance with different properties from the elements that make it. For example: Salt or sodium chloride

8 Bonds forming compounds Atoms can form 3 types of bonds: Ionic involves a complete transfer of electrons; occurs between metals & non-metals Covalent involves the sharing of electrons; occurs between two non-metals Metallic occurs when two metals share electrons

9 Why Do Atoms Form Compounds? Most atoms are not chemically stable by themselves. They form chemical bonds with other elements to become stable. Elements in Group 18 are chemically stable by themselves.

10 Minerals must have the following characteristics: 1. Naturally occurring formed by a geologic process 2. Solid at Earth s surface 3. Crystalline structure atoms are arranged in an orderly & repetitive fashion 4. Definite chemical composition are chemical compounds made of two or more elements 5. Inorganic usually

11 Mineral Formation Minerals generally form in one of 4 different ways: Crystallize from magma Precipitation Changes in temperature & pressure Form from hydrothermal solutions

12 Crystallization from Magma Elements combine to form minerals as magma cools. Examples Feldspar Quartz Muscovite (mica) Hornblende

13 Precipitation Water holds a lot of dissolved substances. As it evaporates, it leaves behind many of these substances. Changes in the temperature of the water may also cause minerals to form. Examples Calcite Halite (salt)

14 Pressure & Temperature Changes in temperature and pressure can cause minerals recrystallize or become unstable. New minerals will form as a result. Examples Talc Muscovite (mica)

15 Hydrothermal Solutions Chemical reactions occur when hot water ( C) comes into contact with minerals. New minerals form as a result of these reactions. Examples Bornite Chalcopyrite

16 Mineral Groups Minerals are placed into one of 6 groups based on their composition. The 6 groups of minerals are Silicates Carbonates Oxides Sulfates & Sulfides Halides Native Elements

17 Silicates Formed when silicon and oxygen combine to form a silicon-oxygen tetrahedron Bond is very strong Most common Made of silicon and oxygen Can form deep below earth s surface or at the surface when other minerals are exposed to weathering Example: garnet

18 Carbonates 2 nd most common Contain carbon, oxygen, & at least one metal Example: calcite, dolomite, limestone, and marble

19 Oxides Contain oxygen and at least one other element that is usually a metal Example: corundum

20 Sulfates & Sulfides Contain sulfur Examples: Gypsum Galena

21 Halides Contain a halogen from group 17 of the periodic table and another element Examples Halite Fluorite

22 Native Elements Only contain one element Examples Gold Silver copper

23 Properties of Minerals Minerals are identified based on a variety of physical and chemical properties. The seven properties used to identify minerals are: Color Streak Luster Crystal Form Hardness Cleavage Fracture Density

24 Color Color is not a very reliable identifying property for a lot of minerals. Small amounts of the different elements can give the same mineral different colors. Some minerals, like sulfur, can be easily identified based on color.

25 Streak Streak is the color of a mineral in its powdered from Streaks usually does not vary from different samples of the same mineral Use the white porcelain plate and the black plate to check the streak of a mineral.

26 Luster Luster is used to describe how light is reflected off the surface of a mineral Types of luster Metallic looks like metal Vitreous, glassy, pearly, silky, and earthy are used to describe non-metallic lusters

27 Crystal Formation Crystal formation is the visible expression of a mineral s internal arrangement of atoms This can be difficult to determine. Not all crystals are allowed enough room to grow and do not immediately show a well developed crystal structure.

28 Hardness Hardness is a measure of the resistance of a mineral to being scratched Minerals tend to have a specific range of hardness. The Mohs scale is used to measure mineral hardness. 10 on the scales is the hardest (diamond), 1 on the scale is the softest (talc)

29 Mohs Scale of Hardness

30 Cleavage Cleavage is the tendency of a mineral to cleave, or break, along flat even surfaces

31 Fracture Minerals that do not show cleavage when broken. Fracture is the uneven breakage of a mineral.

32 Density Density can be used to determine the purity or identity of minerals. Density is equal to the mass of the mineral divided by the volume of the mineral. See pages for a list of some common minerals and their properties.

33 Distinctive Properties Some minerals have very distinctive properties that are unique to them. Sulfur (smell) Graphite (greasy feel) Calcite (bubbles in HCl) Magnetite (is magnetic)