Ch. 3.1 Matter and the Environment

The Gulf of Mexico’s
Dead Zone

•Nutrient-rich runoff causes plankton blooms and
hypoxia—low oxygen levels—in the Gulf of Mexico.
•Hypoxia kills or displaces marine organisms, causing a
decline in the fisheries and the fishing industry.
•U.S. government and farmers debate the need to cut
down on fertilizer use.

Talk About It Do you think the distance between the source of the nitrogen and phosphorus and the dead zones themselves makes it difficult to manage this problem? Why or why not?

Atoms and Elements

• Atoms are the basic unit

of matter.

•Nucleus: Contains
protons and neutrons
•Electrons: Move
around the nucleus

• An element is a

substance that cannot be broken down into other substances.

Did You Know?There are 94 elements
that occur naturally, and scientists have
created about 24 others in labs.

Lesson 3.1 Matter and the Environment

Bonding

• Atoms combine by bonding:

•Covalent bonds: Electrons
are shared.
•Ionic bonds: Electrons are
transferred.

• Molecule: Two or more atoms

joined by covalent bonds

• Compound: Substance

composed of atoms of two or more different elements

Lesson 3.1 Matter and the Environment

Covalent bonding

Ionic bonding

Organic and Inorganic Compounds

•Organic compounds: Consist of covalently bonded carbon atoms and often include other elements, especially hydrogen

•Hydrocarbons: Organic compounds, such as
petroleum, that contain only hydrogen and carbon

•Inorganic compounds: Lack carbon-to-carbon
bonds

Lesson 3.1 Matter and the Environment

Solutions

•A mixture is a combination of elements,
molecules, or compounds that are not
bonded chemically.

•Solutions are mixtures in which all
ingredients are equally distributed.

•Mixtures can be solids, liquids, or gases.

Lesson 3.1 Matter and the Environment

Macromolecules

•Large organic compounds that are essential to life

• Proteins: Serve many functions; include enzymes

• Nucleic Acids: Direct protein production; include

DNA and RNA

• Carbohydrates: Provide energy and structure;

include sugars, starch, and cellulose

• Lipids: Not soluble in water; many functions;

include fats, waxes, and hormones

Lesson 3.1 Matter and the Environment

Water

•Water is required by all living things for survival.

•Hydrogen bonding gives
water many unique
properties:

•Cohesion

•Resistance to temperature
change

•Less dense when frozen

•Ability to dissolve many
other molecules

Lesson 3.1 Matter and the Environment

Acids, Bases, and pH

•The separation of water molecules into ions causes solutions to be acidic, basic,
or neutral.

•The pH scale measures how acidic
or basic a solution is.

•pH of 7—Neutral: Equal
concentrations of H+ and OH-

•pH below 7—Acidic: Relatively
high concentration of H+

•pH above 7—Basic: Relatively
high concentration of OH-

Lesson 3.1 Matter and the Environment