Download Notes Earth Materials plus Qsts

Earth Materials
We can classify or group the earth into 4 basic groups or “sphere’s.
They are:
Atmosphere, Hydrosphere, Biosphere, and the Geosphere.
(These are listed in your textbook. Please refer to Ch 1.1 pp. 7-8)
In this unit we will concentrate on the Geosphere and break it up into different parts to study.
To begin we will cover the lithosphere. This includes the top portion of the earth’s crust.
Below the lithosphere is a zone of material which (because of high temperatures at that depth)
seems to be so weak that it flows like thick tar. This zone is called the asthenosphere (weak
sphere). Below the asthenosphere is a very thick shell extending to a depth of approximately
2900 km. It behaves like something hard or solid. This is called the mesosphere (mantle).
Below the mantle is the core, which extends to the center of the earth, approximately 6371 km
below the surface. The outer core, from 2900 to 5150 km, behaves like a liquid, and the inner
core behaves like a solid.
Elements – The Building Blocks
You have just completed a unit on Chemistry for the Geologist. You should now be familiar
with the terminology used in the following sections.
More than a hundred chemical elements are known. Eight of these elements make up more than
98% of the lithosphere by weight. There are other, many of which you are familiar with but
they are found in very small amounts.
Observe the pie graph and the chart below showing the 8 Most Abundant Elements in the earth.
What can you learn from this table without remembering all the numbers?
Eight Most Abundant Elements in the Earth’s Crust
Element
Oxygen
Silicon
Aluminum
Iron
Calcium
Sodium
Potassium
Magnesium
Symbol
O
Si
Al
Fe
Ca
Na
K
Mg
% of Mass
46.71
27.69
8.07
5.05
3.65
2.75
2.58
2.08
_____
98.58
% of atoms
60.5
20.5
6.2
1.9
1.9
2.5
1.40
1.8
_____
96.70
% of volume
94.24
0.51
0.44
0.37
1.04
1.21
1.85
0.27
_____
99.93
Questions: Answer on a separate sheet of paper.
Remember to use complete sentences, complete
thoughts.
Silicon 28
Oxygen 48
Aluminum
8.1
Magnesium
2.1
Potassium
2.6
Iron 5.1
Calcium 3.7
Sodium 2.8
1. List and describe the “spheres” of our earth.
(refer to the textbook p.p. 7 & 8)
2. List the “layers” of the earth. Describe each as to their
composition, density and consistency.
3. List the eight most abundant elements in the Earth’s
crust in order of most abundant to least.
4. How does the abundance of metals in the earth’s crust compare with the abundance of
oxygen, in mass?
5. . . . in volume?
6. . . . in # of atoms?
7. What is the second most common element in the earth’s crust?
8. Describe how it compares to the amount of all other elements beside oxygen?
Compounds & Minerals
Two or more elements bonded together create a new substance with new and different
properties from the parent elements. In fact most of what we see and use are made of
compounds. The lithosphere is made of many different compounds though the majority is very
similar in composition.
Read textbook p. 44 – 46
Answer the following questions: SEPARATE SHEET OF PAPER
1. Write the definition of a mineral.
2. List and describe the four processes in which minerals form.
Refer back to the reading with the chart on the eight most abundant elements.
Oxygen by far is more plentiful in the lithosphere than any other elements. So the Earth is
really a giant pile of oxygen atoms with a sprinkling of other elements intermixed.
Silicon is the second most abundant element by mass and number of atoms, but is very small in
volume. This means that silicon is a very tiny atom in comparison to oxygen and it makes up
the majority of “other” atoms that are in between the giant oxygen atoms.
In solid compounds all of the atoms in the substance are arranged in a fixed pattern called a
“crystal latticework.” We should expect then to find that one pattern of oxygen and silicon
atoms is the most common. The simplest and more common pattern is one silicon atoms
surrounded by four oxygen atoms. Each of the oxygen atoms is touching the other three, and all
four of them are touching the silicon atom. This is called the silicate tetrahedron. (see diagram
below)
Also see Fig. 14 on p. 48 in text for examples where silicon
And oxygen atoms are shared Forming more elaborate patterns.
Answer the following questions
using your reading and p.p. 47
& 48
1. The most common
combination of atoms
(molecules) is 4 oxygen and 1
silicon. What is this molecule
called?
2. What is the comparison of
the size of an oxygen atom to
the size of a silicon atom?
3. List 3 of the types of silicate
structures that can form from a
single silicate tetrahedron. (p.
48)
Mineral Groups
There are thousands of different
minerals on the earth and all can be classified into eight different groups. You will have the
opportunity to observe the most common ones in class. Now that you have reviewed some
basic chemistry you will also be able to classify each mineral based on reading their chemical
composition.
The most common and the largest group by far is the silicate group since oxygen and silicon are
the most abundant elements in the earth’s crust.
**Complete Mineral Groups Activity:
Review pages 47 – 49 in your text and list the mineral groups and the
elements found in those minerals. List 2 common minerals by name and chemical formula. With each group.