Course 12 Earth Science

Earth Science

Earth science is the study of Earth and its processes. Earth scientists also study Earth relative to other objects in the solar system.

The Four main branches of Earth Science

geology, oceanography, meteorology, astronomy

Geology

Study of the Earth, including its compositional makeup, interior and exterior structure, and processes.

Oceanography

Oceanography is the study of Earth's oceans and the organisms that live in them. Oceanographers analyze the composition and movement of ocean waters and study how ocean waters affect weather and climate. They research ways to protect and preserve Earth's oceans and marine life.

Meteorology

Meteorology is the study of Earth's atmosphere, or the mass of air that surrounds Earth. Processes in Earth's atmosphere are responsible for the weather and climate that occur on Earth's surface. Meteorologists measure data such as air temperature, wind speed or direction, and humidity. By studying the data, meteorologists attempt to predict the weather. In addition, meteorologists study the history of climate, which helps them learn more about the earth's current climate and how it is changing.

Astronomy

Astronomy is the study of celestial objects beyond Earth's atmosphere. The reason these astronomical objects are important to earth science is that they affect systems and processes on Earth. Energy from the sun contributes to many Earth processes, such as evaporation and precipitation. Objects such as meteors and asteroids may enter Earth's atmosphere and strike Earth's surface. These objects can cause significant changes on Earth.

Why Studying Earth Science is Important?

Earth provides valuable resources such as soil, water, metals, industrial minerals, and energy. People need to know how to find these resources and use them sustainably.

The study of rocks and the fossils they contain is important to understand the evolution of the environment and the life within it.

How Scientists Study Earth?

Earth scientists make observations, ask questions, make predictions, and conduct experiments. They draw conclusions and report their findings.

The Seven Scientific Method Steps

Make observations, State the problem, Identify variables, Create a hypothesis, Design an experiment, Collect data, and Draw a conclusion.

Application of the Scientific Method

Sometimes an experiment leads to conclusions that favor a change in approach. Often, an experiment brings entirely new scientific questions to the puzzle. Science doesn't often operate in a linear fashion. Instead, scientists continually draw inferences and make generalizations. They may find new patterns as their research proceeds.

Qualitative and Quantitative Data

Qualitative data include descriptions, observations, and explanations. Qualitative data considers the quality of something, which is not measured numerically, but by traits or categories.

Quantitative data is information that can be verified, measured, or calculated, such as numbers, values, and percentages.

Scientists often organize quantitative data visually using graphics, such as charts, graphs, or tables.

Bar Graph

A bar graph has horizontal or vertical bars. Each bar represents a numerical value—the higher the value, the higher or longer the bar. Bar graphs are very helpful for comparing categories of information. Information is charted along a horizontal x-axis and a vertical y-axis.

Pie Chart

A pie chart is a circular chart divided into slices, each representing a proportion of the whole, or a percentage. Pie charts are helpful in presenting statistical data showing percentages of a whole.

Line Graph

A line graph features a series of points connected by lines. Some line graphs have a single line. Others feature multiple lines that can be compared. Line graphs are especially helpful in showing changes over time.

Scatterplot

On a scatterplot, each piece of data is represented by a dot. Scatterplots are used to find the relationship between two or more variables. Scatterplots make it easy to identify outliers in data. Outliers are values that are very different from the rest of the data.

Timeline

A timeline lists events in the order in which they occurred. Scientists often use timelines to identify significant moments in Earth's history, such as the first appearance of plant life or the disappearance of dinosaurs.

Table

A table arranges data into vertical columns and horizontal rows. The point at which a row and a column intersect is known as a cell. Scientists may include text and/or numerical data in tables.

Sharing Data and Results

A scientific theory offers a thoroughly tested and widely accepted explanation of a phenomenon.

A scientific law, often presented as a formula, offers an observation of a phenomenon without explanation.

Matter

Matter is defined as anything that occupies space and has mass.

Solids, liquids, and gases are the three states of matter commonly found on Earth.

Composition of Matter

All matter is composed of elements. In chemistry, an element is a specific substance that can't be broken down into simpler substances by chemical reactions.

The field of science that describes the composition of matter is chemistry. Attempts to find better methods for refining ore during the Renaissance provided important information to early chemists.

Elements

A total of 118 elements have been defined. only 94 occur naturally on Earth. The remaining 24 elements are unstable and don't exist for very long. Some of these unstable elements can only be produced in extreme conditions, such as in nuclear reactions or in particle accelerators. Each element is designated by its chemical symbol.

Atoms

An atom is the smallest component of an element that retains all of the chemical properties of that element.

Every atom has two numbers: an atomic number and an atomic mass. The number of protons is the atomic number, and the number of protons plus neutrons is the atomic mass.

Molecules

Atoms can combine in certain ways to form molecules. Molecules are chemicals made from two or more atoms bonded together. Some molecules are simple. A molecule of oxygen (O2) is composed of just two oxygen atoms.

An atom or molecule that contains an unequal number of protons and electrons is called an ion. Positive charges (protons) and negative charges (electrons) typically balance each other out in an atom, but an imbalance results in a charged ion.

Covalent bonds

Covalent bonds form when electrons are shared between two atoms. Each atom shares one or more electrons from its outer shell, which are then shared between the nuclei of both atoms, holding the two atoms together.

Covalent bonds are of two types: polar and nonpolar:

A nonpolar covalent bond occurs when electrons are shared equally between two atoms.

Polar covalent bonds form when electrons are shared unequally.

Bonds and Physical Structure

A mineral is a naturally occurring specific combination of elements. The atoms of these elements are arranged in a repeating three-dimensional structure, or lattice.

In halite, atoms of sodium alternate with atoms of chlorine in all three dimensions. The angles between bonds are all 90°. The lattice extends in all three directions for thousands of repetitions. Halite always has this composition and this structure.

Pure Substances

A pure substance has a constant composition. All samples of a pure substance have exactly the same makeup and properties. Any sample of pure sucrose (table sugar) consists of 42.1% carbon, 6.5% hydrogen, and 51.4% oxygen by mass. Any sample of pure sucrose also has the same physical properties, such as melting point, color, and sweetness.

Pure substances can be divided into two classes: elements and compounds:

Elements are pure substances made from a single kind of atom.

Pure substances that are made of more than one type of atom, and so can be broken down by chemical changes, are called compounds.

Mixtures

A mixture is composed of two or more types of matter that can be present in varying amounts. A mixture can be separated by physical changes, such as evaporation. A mixture with a composition that varies from point to point is called a heterogeneous mixture.

Depending on its properties, a given substance can be classified as a homogeneous mixture, a heterogeneous mixture, a compound, or an element.

Physical Properties of Matter

A physical property is a characteristic of matter that is associated with a change such as appearance, texture, state (such as solid, liquid, or gas), but retains chemical properties.

Chemical Properties of Matter

A chemical property is a characteristic of matter associated with a change in its chemical composition.

Elements with Similar Properties

Sets of elements can be identified that exhibit common behaviors such as conduction, in which an element or compound transmits energy to another element or compound. These properties can be used to sort the elements into three classes: metals, elements that conduct well; nonmetals, elements that conduct poorly; and metalloids, elements that have properties of both metals and nonmetals. In the periodic table, elements with similar properties are grouped together.

Minerals in Everyday Life

Minerals are used to make everything from cars, computers, appliances, concrete roads, and houses to tractors, fertilizers, electrical transmission lines, and jewelry.

Minerals and Economics

Minerals typically are mined from ore deposits, which are areas with a high concentration of minerals. Minerals may be mined from Earth's surface or from deep underground. Once minerals have been mined, they're processed into usable materials by crushing or grinding.

The Formation of Minerals on Earth

Scientists believe that probably about a dozen minerals existed in cosmic dust. When the sun formed, it heated these tiny particles of dust, and they melted into droplets called chondrules. The chondrules began to collect in early meteorites, forming chondrites.

Earth's Older Minerals

As of 2018, the oldest known minerals on Earth are zircon crystals from the Jack Hills region of Australia. Scientists estimate that these crystals are approximately 4.4 billion years old, which means they came into existence shortly after Earth's formation

Characteristics of Minerals

Mineralogists are scientists who study minerals; they define a mineral as a naturally occurring inorganic solid with a defined chemical composition and crystal structure.

Naturally Occurring

Minerals are "naturally occurring" because they are formed by natural processes, interactions in nature that occur without human input. Photosynthesis is a natural process. The rise and fall of the tides are natural processes.

Three Factors for a minerals crystal grow:

The elements needed to make it must be present in the appropriate proportions.

The physical and chemical conditions must be favorable.

There must be sufficient time for the atoms to become arranged.

Following are some other natural processes that produce minerals:

Organically formed minerals are still considered minerals because they can also form inorganically.

• Precipitation from aqueous solution: hot water flowing underground, evaporation of a lake or inland sea, or in some cases, directly from seawater.

• Precipitation from gaseous emanations, such as in volcanic regions.

• Metamorphism, in which new minerals form directly from the elements within existing minerals under conditions of elevated temperature and pressure.

• Weathering, during which minerals unstable at Earth's surface may be altered to other minerals.

• Organic formation of minerals within shells, primarily calcite, and teeth and bones, primarily apatite, by organisms.

Inorganic Substances

Minerals are inorganic substances. Inorganic substances aren't derived from or made by living matter, such as plants or animals.

Crystal Structure

A crystal is a solid material in which the atoms are arranged in a lattice. The crystal structure of a mineral determines its physical properties.

Chemical Composition

A unique crystal structure, minerals have a specific chemical composition. Some are made up of atoms of a single element such as diamonds and graphite, made entirely of carbon (C) atoms.

Classification of Minerals

Scientists classify minerals into groups based on their chemical composition and structure. Most minerals fall into one of these eight groups: (oxides, sulfides, sulfates, halides, carbonates, phosphates, silicates, native elements

Oxides

Oxides are minerals composed of compounds that contain atoms of oxygen bonded to one or more metals.

Sulfides

Sulfides are minerals composed of compounds that contain atoms of sulfur and one or more metals.

Sulfates

Contain sulfate molecules (one sulfur atom bonded to four oxygen atoms) bonded to atoms of metals

Halides

Halides are minerals composed of compounds that contain atoms of the halogen gases—bromine, chlorine, fluorine, and iodine—and one or more metals.

Cabonates

Carbonates are minerals composed of compounds that contain carbonate molecules—one carbon atom bonded to three oxygen atoms (CO3).

Phosphates

Phosphates are minerals composed of compounds that contain phosphate molecules—one phosphorous atom bonded to four oxygen atoms (PO4).

Silicates

Silicates are minerals composed of compounds that contain molecules of silicon and oxygen bonded to atoms of one or more metals.

Native Elements

Native elements are minerals composed of atoms from a single element.

AN IN-DEPTH LOOK AT SILICATES:

Silica Tetrahedron

The building block of silicate minerals; includes one silicon atom bonded to four oxygen molecules in a triangular pyramid shape

MINERAL PROPERTIES:

COLOR

Color is a key way of identifying objects. While some minerals have particularly distinctive colors that make good diagnostic properties. For many minerals, color is unreliable.

STREAK

The color of a mineral in powdered form.

LUSTER

The way light reflects off the surface of a mineral and the degree to which it penetrates into the interior

HARDNESS

A measure of how easily a mineral can be scratched.

CRYSTAL HABIT

In minerals, the external shape of one crystal or crystal group.

CLEAVAGE AND FRACTURE

Crystal habit is a reflection of how a mineral grows. Cleavage and fracture describe how a mineral breaks. Cleavage is what you see when a mineral breaks along a specific plane or planes. Fracture is an irregular break.

DENSITY

Density is a measure of the mass of a mineral per unit volume.

IGNEOUS ROCKS:

Three main categories

• Igneous: Formed from the cooling and crystallization of magma.

• Sedimentary: Formed when weathered fragments of other rocks settle to the seafloor and are buried, compressed, and cemented together or when minerals precipitate directly from solution

• Metamorphic: Formed by alteration of a preexisting igneous or sedimentary rock.

Formation of Igneous Rock

Rock typically becomes magma at temperatures between about 800°C and 1300°C (1472° to 2372°F), depending on its composition and the pressure. Magma that erupts onto Earth's surface is called lava.

Understanding Magma:

Eight Elements

1. Oxygen

2. Silicon

3. Aluminum

4. Iron

5. Calcium

6. Sodium

7. Magnesium

8. Potassium

Oxygen

The most abundant element in magma. Slightly more than a quarter of magma is made of silicon. The remaining elements make up the other quarter. Magma derived from material in Earth's crust is dominated by oxygen, silicon, aluminum, sodium, and potassium.

Crystallization

A body of intrusive igneous rock that forms within Earth's crust is called a pluton. Plutons form when magma rises toward the surface.

Intrusive: Igneous rock formed from magma that cools slowly within Earth's crust

Lava: Magma that erupts onto Earth's surface