Ecology and Environmental Science Basics

Study Notes

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.

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.

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.

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).

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.

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.