Ecology and Environmental Science Basics

Ecology and Matter

• Ecology is the scientific study of relationships between organisms and their environment.
• Matter is everything that takes up space and has mass, and it exists in three distinct states: solid, liquid, and gas.

States of Matter and Elements

• Water can exist in all three states: ice (solid), water (liquid), and vapor (gas).
• Matter is transformed and combined in different ways, but it doesn't disappear; it's either created or destroyed, and recycled over and over again.
• Matter is made of atoms, molecules, and compounds.
• Elements are substances that cannot be broken down into simpler forms by ordinary chemical reactions.
• There are 122 known elements, with 92 being natural and 30 created under special conditions.
• Each element has distinct chemical characteristics.

Atomic Structure

• Atoms are the smallest part of an element, composed of positively charged protons, negatively charged electrons, and electrically neutral neutrons.
• Each element has a characteristic number of protons, called its atomic number.
• Atomic mass is the sum of protons and neutrons in each nucleus.
• Isotopes are forms of a single element that differ in atomic mass.
• Examples of isotopes include deuterium (H2) and tritium (H3), which are forms of hydrogen.

Molecules and Chemical Bonds

• A molecule is a group of atoms that can exist as a single unit, such as O2, Na2, and H2.
• Chemical bonds hold molecules together.
• Atoms often join to form compounds, such as glucose (C6H12O6).
• Examples of common molecules include hydrogen chloride (HCl), water (H2O), and carbon dioxide (CO2).

Chemical Reactions and Energy

• Energy is required to break down chemical bonds.
• Reactions that release energy are exothermic, such as burning wood, which releases heat.
• Activation energy is needed to initiate chemical reactions.
• Examples of activation energy include a match or spark that initiates combustion.

Electrical Charge and Ions

• Atoms can gain or lose electrons, acquiring a negative or positive electrical charge.
• Charged atoms are called ions.
• Negatively charged ions are called anions, while positively charged ions are called cations.
• An example of an ion is a hydrogen ion (H+), which is formed when a hydrogen atom gives up its sole electron.