Transcript Waves
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 • Oceanic – _______ • Lithosphere • Asthenosphere • Mesosphere -- _______ Inner Outer 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 5500oC • 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 (Mg2+) • 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 eCu 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 ____________(Mg2+) • 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 metalcontaining materials by ______________________________________ Study Buddy Review • • • • What is the activity series of metals? What is oxidation? What is reduction? What is an oxidizing agent?