Earth’s Mineral ResourcesUnit 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 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 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 ____________(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 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?