Presentation on theme: "Chapter 5 Atoms, Elements, and Minerals. The next few chapters in geology are mostly about rocks. Nearly all rocks are made of minerals, so in order to."— Presentation transcript:
Chapter 5 Atoms, Elements, and Minerals
The next few chapters in geology are mostly about rocks. Nearly all rocks are made of minerals, so in order to learn about rocks you need to know something about minerals. In Chapter 5, you will discover that: 1.Each mineral is made up of specific chemical elements, the atoms of which are organized in a special arrangement. 2.The chemical makeup and its internal structure determine an elements physical properties. 3.A mineral can be identified by its physical characteristics, such as: cleavage, crystal form, fracture, hardness, lustre, colour, streak, and specific gravity.
What is Matter? Matter – the substance of which any physical object is composed. Everything is made of matter. States of Matter: Solid Liquid Gas Controlling factors: Temperature Pressure Examples: Gold Mercury Oxygen solid liquid gas
The stuff that makes up all matter The make-up of solid matter on Earth: Atoms Elements Compounds Minerals Rocks (smallest) (largest) What is an atom? An atom is the smallest particle of a matter that keeps the properties of that matter. For example, all sodium atoms are essentially identical to all other sodium atoms. Water (H 2 O) can be broken down into two atoms of hydrogen (H) and one atom of oxygen (O).
What are elements? Elements are the fundamental building blocks of matter. Elements cannot be broken down into smaller units. Elements are pure substances and are made of one or more of the same type of atoms. All elements are listed in the periodic table of the elements.
Periodic Table of Elements
Element abundances in the crust All others: 1.5%
What are the most abundant elements in the Earths crust? 1.Oxygen (O) -Oxygen is the most abundant element in the crust (makes up about 50% of the crust) -Oxygen bonds easily with other elements
2.Silicon (Si) -Most silicon form bonds with oxygen to form silica -Quartz (SiO 2 ) is pure silica that has been crystalized -Any mineral that contains silica is called a silicate
3.Aluminum (Al) -Aluminum is more common that iron, but difficult to separate from rocks because it binds very tightly with oxygen. Other elements in the Top 8 include: IronPotassium CalciumMagnesium Sodium
Mineral characteristics Definition of a Mineral: 1.naturally occurring 2.inorganic 3.solid 4.characteristic crystalline structure 5.definite chemical composition steel plastic sugar table salt mercury ice coal basalt obsidian mica gold paper chalk coral no, #1 no, #1,2YES!no, #3YES!no, #2 no, #5no, #4YES! no, #1,2no, #2 QUIZ!!!
Mineral characteristics Naturally formed –No substance created artificially is a mineral. examples: plastic, steel, sugar, paper Inorganic –Anything formed by a living organism and containing organic materials is not a mineral. examples: wood, plants, shells, coal Solid –Liquids and gases are not minerals. examples: water, petroleum, lava, oxygen
Mineral characteristics Characteristic crystalline structure –must have an ordered arrangement of atoms –displays repetitive geometric patterns in 3-D glass not a mineral (no internal crystalline structure) Definite chemical composition –must have consistent chemical formula examples: gold (Au), quartz (SiO 2 ), orthoclase (KAlSi 3 O 8 ) basalt (like many other rocks) contains variable ratios of different minerals; thus, has no consistent formula
–Only ~30 occur commonly (whew!) –Why not more? Some combinations are chemically impossible Relative abundances of elements dont allow more How many minerals are there? Nearly 4,000 types of minerals
Silicates Most minerals are silicates (which means they contain silicon & oxygen) Silicates have a very special structure called a tetrahedron. This tetrahedron is the building block of a the silicate crystals
Silicate tetrahedrons can combine together to make much bigger structures. Diamond is NOT a silicate, but pure crystallized carbon. It is a very strong tetrahedron (and also a mineral).
Minerals of the Earths Crust The following are silicate minerals. They are the most common minerals and make up about 90% of the crust. 1.Feldspars 2.Quartz 3.Pyroxenes 4.Amphiboles 5.Micas
Feldspar Pyroxene Quartz Amphibole Mica
Other common mineral crystals include: 1. Clay minerals (which is another group of silicates) 2. Non-silicates Example: gypsumExample: calcite