chapter 2: minerals 2.1 – matter 2.2 – minerals 2.3 – properties of minerals

Chapter 2: Minerals2.1 – Matter

2.2 – Minerals2.3 – Properties of Minerals

2.1 Matter

• What is an element?

• What particles make up atoms?

• What are isotopes?

• What are compounds and why do they form?

• How do chemical bonds differ?

Show what you know!

• Work with a partner

• Discuss what you already know about atoms

• Draw a picture of an atom based on what you and your partner know

• Include as many details as possible!

What is an element?

• An element is a substance that cannot be broken down into simpler substances by chemical or physical means• Elements are the basic building

blocks of minerals (and everything else!)

• The 3 basic types of elements are metals, nonmetals, and metalloids

Periodic Table of the Elements

What is an element?

• Elements are organized by their properties on the periodic table

What is the universe made of? - Dennis Wildfogel

Atomic number

Element symbol

Element Name

Atomic mass

What is an element?

Most Common Elements in Earth’s Continental Crust

Element % by Weight

Oxygen (O) 46.6

Silicon (Si) 27.7

Aluminum (Al) 8.1

Iron (Fe) 5.0

Calcium (Ca) 3.6

Sodium (Na) 2.8

Potassium (K) 2.6

Magnesium (Mg) 2.1

Others 1.7

What particles make up atoms?

• Nucleus• Protons – positively charged particles• Neutrons – neutral particles

• Electron Cloud• Electrons – negatively charged particles

What particles make up atoms?• The identity of an atom is

determined by it’s number of protons, or atomic number.

• The atomic mass of an atom is equal to the number of protons plus the number of neutrons

• The electrons in an atom are involved in chemical bonds with other atoms

What are Isotopes? Video: How Does Radiocarbon Dating Work?• Atoms with the same number of

protons but different numbers of neutrons are isotopes of an element• Isotopes have a different mass

number than other versions of the same element

What are Isotopes?

• An atom that creates isotopes easily is known as unstable• Unstable atomic nuclei disintegrate in a

process called radioactive decay• The rate of this decay is measurable so

radioactive elements can be used to determine the age of fossils, rocks, and minerals

What are compounds and why do they form?• A compound is a substance that consists of two or more elements

that combine in specific proportions

What are compounds and why do they form?

+

• Atoms form compounds in order to become more stable

• Video - Sodium in Water

What are compounds and why do they form?

What are compounds and why do they form?

What are compounds and why do they form?

Ionic Bonds Covalent Bonds Metallic Bonds

• Ions form when an atom gains or loses electrons and becomes charged ( + or -)

• Ionic bonds form between positive and negative ions

• Rigid solids with high melting and boiling points

• Conduct electricity when melted or dissolved in water

• Examples: NaCl (table salt) CaCl (chalk)

• Covalent bonds form when atoms share electrons

• Have low boiling and melting points

• do not conduct electricity• Examples: H2O (water) SiO2 (quartz)

• Metallic bonds form when atoms are shared between metallic ions

• Malleable & ductile – can be bent or drawn into wires

• Conduct electricity• Examples: Cu (copper) Fe3C (steel)

2.2 Minerals

• What are five characteristics of a mineral?

• What processes result in the formation of minerals?

• How can minerals be classified?

• What are the major groups of minerals?

A mineral is a naturally occurring, inorganic solid with an orderly crystalline structure and a definite chemical composition.

• Naturally occurring- forms from geologic processes• Solid substance- hard at normal temperatures• Orderly crystalline structure- atoms are arranged in orderly repetitions• Definite chemical composition – made of the same elements for any sample.• Generally considered inorganic- not from living things

How do minerals form?

1. Crystallization from magma- elements combine in an orderly structure when magma cools underground

2. Precipitation- minerals fall out of solution because the water evaporates or changes temperature

3. Pressure and temperature- minerals can change form when heated or compacted

4. Hydrothermal solutions- very hot water with dissolved substances can form new minerals

How can minerals be classified?

•Minerals are classified into groups based on their chemical composition•Common mineral groups include: silicates, carbonates, oxides, sufates and sulfides, halides, and native elements.

Silicates

• The silicon-oxygen tetrahedron forms the framework of every silicate mineral. • 90% of Earth’s crust is composed of

silicate minerals• Sand, glass, bricks, stones, soil,

concrete, quartz• Piezoelectric effect – quartz produces

an electric charge when compressed, bent or twisted (watches & radio receivers)

AmethystGarnetOlivineOpal

Silicates

Carbonates

• Carbonates contain CO3 ions

Aragonite Cave in Slovakia

Carbonates

Calcite was used for gun sights in WWII because it is fluorescent under UV light

Oxides• Contain oxygen and metal ions• Bauxite (aluminum ore): requires

a lot of energy to process into aluminum which is why aluminum is commonly recycled

Aluminum Ore Tin Ore

Iron Ore

Copper Ore

Uranium Ore

Sulfates and Sulfides

• Contain the element sulfur• The mineral gypsum is

used in drywall and plaster of paris

Crystal Cave,Naica Mexico

Halides

• Contain halogens (group 7 on the periodic table)• Fluorite is a source of fluoride which is used in toothpaste• Halite is the mineral name for table salt

Native Elements

• Native elements are minerals that contain only one type of element (only one type of atom)

2.3 Properties of Minerals

• What properties can be used to identify minerals?• What is the Moh’s Scale?• What are some distinctive properties of minerals?

• Mineral properties depend on the elements that compose the mineral and it’s structure

What properties can be used to identify minerals?Color• Not actually very useful• Small amounts of different elements can give the same mineral

different colors

What properties can be used to identify minerals?Streak• Streak is the color of the mineral in powdered form. • Find streak by rubbing a mineral against a streak plate

Galena Sulfur Pyrite Calcite Olivine LodestoneObservation – Observation - Observation - Observation - Observation - Observation -

What properties can be used to identify minerals?Luster• Describes how light is reflected from the surface of a mineral

Obsidian Galena Gypsum HematiteGlassy luster Metallic luster Silky luster Earthy luster

What properties can be used to identify minerals?Crystal form• Visible expression of a mineral’s internal arrangement of atoms

Bismuth Crystal Structure (lab grown)

What properties can be used to identify minerals?What is the Moh’s scale?Hardness• The Moh’s scale is a standard scale used to compare the hardness of

minerals

What is the Moh’s scale?

Mineral Mini-Lab• You will be given a mineral to test for hardness using various objects

of known hardness. • To test your mineral, rub the mineral against the object and check for

scratches. • If a mineral scratches an object, the mineral is harder than the object.• If an object scratches a mineral, the mineral is softer than the object.

• Answer the questions for each object used to test your mineral. • As a class, rank each item from hardest to softest

What is the Moh’s scale?

Mineral # ____

1. Is your mineral harder than a fingernail?2. Is your mineral harder than a copper penny?3. Is your mineral harder than a wire nail?4. Is your mineral harder than a piece of glass?

What is the Moh’s scale?

What properties can be used to identify minerals?Cleavage• The tendency of a mineral to

cleave, or break along flat, even surfaces

Crystal structure of mica

What properties can be used to identify minerals?Fracture• Fracture is the uneven breakage of a mineral• Minerals show either cleavage or fracture

What properties can be used to identify minerals?Density• The density of a pure mineral is a constant value. • Density can be used to determine the purity or identity of some

minerals• How taking a bath led to Archimedes' principle - Mark Salata

What are some distinctive properties of minerals?

• Some minerals can be recognized by other distinctive properties

Talc Magnetite Sulfur Calcite GraphiteFeels soapy magnetic Smells like

rotten eggsFizzes when dropped with HCl

Feels greasy