Download Notes Earth Materials 3rd and 6th hr.s

Notes - Earth Materials (with Questions)
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.
1
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.
There are 4 “spheres” of our earth: hydrosphere,
atmosphere, biosphere and Geosphere. This semester we
are focusing on the Geosphere.
(refer to the textbook p.p. 7 & 8)
2.
List the “layers” of the earth and describe:
composition, density and consistency.
Crust/lithosphere - __solid, very thin layer of mostly silicate rocks_________________
Mantle : Asthenosphere_”plastic” like layer of rock at the very top of mantle_________
Mesosphere___solid, very dense rock__________________________________
Core : Outer – ___liquid heavy metals such as iron & nickel________________________
Inner - ___solid heavy metals such as iron & nickel_________________________
3. List the eight most abundant elements in the Earth’s crust in order of most abundant to least.
O, Si, Al, Fe, Ca, Na, K, Mg
4. How does the abundance of metals in the earth’s crust compare with the abundance of
oxygen, in mass? Way more O2 almost 47% of all mass in the crust is oxygen
5. . . . in volume? By far, Oxygen is the biggest atom. 94% of the volume(space) in the crust is taken up by
oxygen atoms
6. . . . in # of atoms?if you could count every atom in the crust over 60% of them would be oxygen!!
7. What is the second most common element in the earth’s crust? silicon
8. Describe how it compares to the amount of all other elements beside oxygen?a distance 2nd at
30% and 20% in weight and sheer numbers of atoms. The volume, 0.5% indicates it is a very tiny atom.
2
Compounds & Minerals
A Compound is - 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
1. Write the definition of a mineral. (5 parts)
a. ___naturally occuring_______________________________
b. ___inorganic (not living material)________________________________________
c. ___solid________
d. ___distinct crystalline structure______
e. ___specific chemical formula__________________________
2. List and describe the four processes in which minerals form.
a. Crystalization of _____________
b. Precipitation of ___________________
c. Pressure & high Temperature. Mixing and __________________________
d. Hydrothermal ____________________ - _____________________________
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 atom surrounded by _four__ oxygen atoms. Each of
the __four____ atoms is touching the other three, and all four of
them are touching the __silicon___ atom. This is called the
_silicate___ tetrahedron___. (see diagram to the left)
Also see Fig. 14 on p. 48 in text for examples where silicon
And oxygen atoms are shared forming more elaborate patterns.
3
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 at least 3 of the types of
silicate structures that can form
from a single silicate
tetrahedron. (p. 48,for a larger
version of the diagram to the left)
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:
pages 47 – 49 in your text
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