Earth’s Mineral Resources Unit 2 Sect B Environmental Chemistry

Coin-Design Competition One requirement for the new coin is to specify the coin’s material/composition We have studied the elements Where are the elements located on Earth? First a little background about the earth’s structure

Cross Section of the Earth

Cross Section of Earth Earth can be divided into 3 main layers based on the materials that make up those layers –_____-- _______ Continental Inner Oceanic Outer –_______ Lithosphere Asthenosphere Mesosphere

Earth’s Crust Rocky outer layer of earth is the crust Thin compared to other layers Mostly made of ___________ (elements silicon and oxygen), aluminum, iron, calcium

Two Types of Earth Crust Continental crust: the rock that makes up the earth’s continents –Averages 40 km thick Oceanic crust: rock that makes up ocean floor –Averages 7 km thick

The Mantle Earth’s mantle: thick layer of solid rock below earth’s crust –About 2850 km thick –Mostly made of _____________ –More dense than crust Pressure and temperature increases as you get deep inside the earth

Three Layers of Mantle Lithosphere: ____________ part of mantle –Cool, rigid rock Asthenosphere: middle part of mantle –Softer, weak layer, flows like taffy Mesosphere: bottom part of mantle –Strong and stiff rock layer

The Core The core is a large sphere of metal that occupies Earth’s center –Mostly made of _______(allows for earth’s magnetic field) –Very high pressure! Almost 3.6 million times that of earth’s surface –Temperature: about 5500 o C Outer core: liquid metal (high temp) Inner core: solid metal (high pressure)

Study Buddy Review What are the three main layers of the Earth? What happens to the temperature and the pressure as you descend into the Earth? Which metal is in the core of the Earth? Why is that important?

Sources and Uses of Metals

Sources of Elements on Earth Atmosphere: _______________________ Hydrosphere: water components of the earth’s surface Lithosphere: solid part of earth

Sources of Metals Ore: naturally occurring ______________ ______________________ and from which it is profitable to extract a metal or other material. Minerals: naturally occurring solid compounds containing the element of interest

Study Buddy Review What is the atmosphere? What are minerals? What is a metal ore?

Metal Properties and Uses

Historic Use of Metals Gold and silver were probably the first metals used by humans. –Found as free elements (not in ores/compounds) –Decorative –__________________

Historic Use of Metals Copper used ~10,000 years –Bronze (alloy of _________________) developed about 3800 BC –Alloy: mixture (solution) of different metals Iron metallurgy (extract iron from iron ore) led to Iron Age ~3000 BC

Study Buddy Review Why were the elements gold and silver probably the first used by humans? What is bronze? When was the Iron Age?

Activity Series

Coinage Metals Group 11 (Cu, Ag, Au) are sometimes called the coinage metals –_______________________________________ What results did you get for the reactivity of silver in the lab?

Reactivity of Metals Lab In what order of reactivity did you place the metals tested in lab? –Reactivity means corrosion, formation of new compound, creation of coating, etc. ________________________ Is there an order of reactivities of metals in nature?

Activity Series of Metals __________________________ metal elements ranked in order of their chemical reactivity. Most reactive metals at the _____ of the list (Mg) Least reactive metals at the ___________ of the list (Au) Most reactive metals have low reactive ion in solutions (Mg 2+ ) Least reactive metals have highly reactive ion in solutions (Ag + )

How do Metals React? When metals react, they lose electrons When atoms lose electrons, they form _______________ charges Process is called _________________ Mg (s)  Mg 2+ (aq) + 2 e- Where did the electrons go? Electrons flow to another substance

Substances That Accept Electrons Substances that ______electrons undergo a process called _________________: Cu 2+ (aq) + 2 e-  Cu (s)

Redox Reactions Oxidation reactions always accompany reduction reactions Called _____________________ OIL RIG –Oxidation is losing electrons –Reduction is gaining electrons

Redox Reactions Cu 2+ (aq) + 2 e-  Cu (s) Mg (s)  Mg 2+ (aq) + 2 e- Cu 2+ (aq) + Mg (s)  Cu (s) The number of electrons are always conserved ______________________________________ ______________________________________ The flow of electrons can be used to create electrical energy.

Summary of Oxidation and Reduction Oxidation Lose electrons e- appear on right side of arrow in equation Charge number becomes more positive Reduction Gain electrons e- appear on left side of arrow in equation Charge number becomes more negative

Oxidizing and Reducing Agents Oxidizing Agents: are the substances that are ____________(Mg 2+) Reducing agents: are the substances that are ____________(Cu)

Other Methods for Isolating Metals Electrometallurgy: involving the use of ________________________ to supply electrons to metal ions and reducing them Pyrometallurgy: the treatment of metals and their ores by _________________ –Oldest ore-processing method Hydrometallurgy: obtaining metals from their ions by treatment of ores and other metal- containing materials by ______________________________________

Study Buddy Review What is the activity series of metals? What is oxidation? What is reduction? What is an oxidizing agent?