bio- chapter 2

Vocabulary flashcards covering key concepts from the video notes on matter, elements, bonds, water chemistry, ocean acidification, and evidence for water on Mars.

Coral reef decline due to CO2 acidification

CO2 dissolves in seawater forming carbonic acid, lowering pH and reducing carbonate availability for coral skeletons.

Matter

Anything with mass that occupies space, including solids, liquids, and gases.

Element

Pure substance that cannot be broken down into simpler substances by chemical means; 92 natural elements exist.

Compound

A substance made of two or more elements in a fixed ratio.

Major elements of the body

Oxygen (O), Carbon (C), Hydrogen (H), Nitrogen (N), Calcium (Ca), Phosphorus (P) — make up about 99% of the body.

Subatomic particles

Protons (positive, define element), Neutrons (neutral, add mass), Electrons (negative, orbit nucleus and bond).

Atomic number

The number of protons in the nucleus; defines the element.

Mass number

Total number of protons and neutrons in the nucleus.

Isotopes

Variants of the same element with different numbers of neutrons.

Stable isotopes

Isotopes whose nuclei do not decay over time.

Emergent properties

New properties that arise when elements combine to form compounds (e.g., Na + Cl → NaCl).

Trace elements

Elements required in small amounts (<0.01% of body) but essential (e.g., Fe, I, Zn).

Atoms and subatomic particles

Atom: smallest unit of an element retaining its properties; Protons, Neutrons, Electrons.

Proton

Positively charged subatomic particle; its number defines the element (atomic number).

Neutron

Neutral subatomic particle; contributes to atomic mass.

Electron

Negatively charged subatomic particle; forms the electron cloud and participates in bonding.

Radioactive isotopes

Nuclei that decay over time, releasing energy.

Iodine (I)

Vital for thyroid hormone; deficiency causes goiter; iodized salt is a remedy.

Iron (Fe)

Essential for oxygen transport and energy processing.

Fluoride (F)

Strengthens teeth; added to water and toothpaste.

Tracers

Radioactive or stable isotopes used to follow chemical processes (e.g., C-14 in photosynthesis).

PET scans

Imaging method using radioactive tracers to detect brain activity and disease.

Dangers of radiation

High exposure can damage molecules, especially DNA.

Public health vs individual rights

Balancing scientific evidence with social concerns in health decisions (e.g., fluoridation).

Ocean acidification

Oceans absorb CO2, forming carbonic acid and lowering pH, reducing carbonate ions for calcification.

Calcification

Process by which corals build their calcium carbonate skeletons.

Carbonate ion (CO3) and bicarbonate (HCO3)

Key species in seawater carbonate chemistry affected by acidification.

Independent variable (concept in coral studies)

The variable deliberately changed (e.g., carbonate ion concentration) to observe effects.

Dependent variable (coral studies)

The variable measured (e.g., calcification rate) in response to changes.

Volcanic CO2 seeps (champagne reefs)

Natural low-pH environments used to study effects of CO2 on reefs.

pH

A scale (0–14) measuring how acidic or basic a solution is; 7 is neutral.

pH in coral studies

Lower pH (more acidic) correlates with reduced coral growth and diversity.

H⁺ and OH⁻ in water

Water ionizes into hydrogen (H⁺) and hydroxide (OH⁻) ions, affecting chemistry.

Buffers

Substances that resist pH changes by neutralizing added acids or bases.

Carbonic acid

Weak acid formed when CO2 dissolves in water; lowers pH.

Water as solvent of life

Water dissolves many solutes; essential for blood, body fluids, and metabolism.

Aqueous solution

Solution in which water is the solvent.

Polarity of water

Water's polar molecule allows it to surround and dissolve ions and polar molecules.

Ionic bonds

Transfer of electrons between atoms, creating oppositely charged ions that attract.

Covalent bonds

Atoms share electrons to complete outer shells.

Nonpolar covalent bond

Electrons shared equally (e.g., C–H bonds in methane).

Polar covalent bond

Electrons shared unequally due to electronegativity differences (e.g., H2O).

Valence

Number of covalent bonds an atom can form.

Hydrogen bonds

Weak bonds between polar molecules (e.g., between water molecules) driven by partial charges.

Molecular representations

Molecular formula (e.g., H2O); structural formula (bonds as lines); space-filling model; electron distribution diagram.

Ionic strength in environment

Bond strength of ionic compounds varies: strong in dry crystals, weaker in water.

Hydrogen bonding and biology

Hydrogen bonds help shape proteins and pair DNA bases; essential in biology.

Photosynthesis

6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2; stores energy in chemical bonds.

Conservation of matter

Matter is not created or destroyed in chemical reactions; only rearranged.

Chemical reactions

Breaking and forming bonds to rearrange atoms (e.g., 2H2 + O2 → 2H2O).

Ice density and freezing

Ice is less dense than liquid water due to crystalline hydrogen-bond structure, causing ice to float.

Ice's ecological role

Floating ice insulates liquid water, helping aquatic life survive winter.

Solvent properties of water

Water dissolves salts and polar substances; essential for nutrient transport in organisms.

2.13 Water as solvent specifics

Water surrounds ions and polar molecules, enabling dissolution (e.g., Na+ and Cl− in salt).

2.14 Acids and bases (pH scale)

Acid donates H⁺; base reduces H⁺ concentration; pH scale ranges 0–14 with 7 neutral.

Buffers (biological relevance)

Accept or donate H⁺ to stabilize pH in cells and blood.

Mars water evidence (2.16)

Ice caps, subsurface ice, clay minerals, and lander/rover findings indicate past/present water on Mars.

Significance of Martian water findings

Supports possibility of past or present life and informs evolution of planetary environments.