Chapter 2 - The Chemical Foundation of Life (Vocabulary Flashcards)

Vocabulary flashcards covering atoms, isotopes, bonds, water properties, pH and buffers, carbon backbone, hydrocarbons, and functional groups from Chapter 2.

Atom

Smallest unit of matter that retains the properties of an element; consists of a nucleus (protons and neutrons) and an electron cloud.

Element

Substance that cannot be broken down into simpler substances by chemical reactions; defined by its number of protons.

Atomic number

Number of protons in an atom; identifies the element.

Atomic mass

Sum of the protons and neutrons in the nucleus; approximately 1 Dalton per nucleon.

Nucleus

Center of the atom that contains protons and neutrons.

Proton

Positively charged subatomic particle located in the nucleus.

Neutron

electrically neutral subatomic particle located in the nucleus.

Electron

Negatively charged subatomic particle that orbits the nucleus in electron shells.

Isotope

Atoms of the same element with different numbers of neutrons.

Radioactive isotope

Isotopes that are unstable and emit particles and energy.

Ion

Atom or molecule with a net electric charge due to loss or gain of electrons.

Cation

Positively charged ion formed when an atom loses electrons.

Anion

Negatively charged ion formed when an atom gains electrons.

Valence electrons

Electrons in the outermost shell that determine chemical behavior.

Valency

Number of unpaired valence electrons; indicates bonding capacity.

Covalent bond

formed by sharing electrons to complete valence shells.

Ionic bond

Bond formed by electrical attraction between oppositely charged ions after electron transfer.

Polar covalent bond

Covalent bond with unequal sharing of electrons due to electronegativity differences.

Nonpolar covalent bond

Covalent bond with equal sharing of electrons.

Electronegativity

Attraction of an atom for electrons in a covalent bond; increases with more protons, more electrons, and closer distance to the nucleus.

Electronegativity factors

Determined by the number of protons, the number of electrons, and the distance of outer electrons from the nucleus.

Molecule

Two or more atoms covalently bonded together.

Compound

Two or more different elements bonded in a fixed ratio.

Structural formula

Representation with lines indicating shared electron pairs.

Molecular formula

Indicates the number and types of atoms in a molecule.

Emergent properties

New properties that arise from the arrangement of atoms in a compound and are not predictable from its individual elements.

Hydrogen bond

Intermolecular attraction where a hydrogen atom bound to a highly electronegative atom is attracted to another electronegative atom.

Hydrophilic

Affinity for water; polar or charged substances that dissolve in water.

Hydrophobic

Lack of affinity for water; nonpolar substances that do not dissolve well in water.

Polarity

Feature of a molecule with an uneven distribution of electrical charge.

States of water

Liquid, solid (ice), and gas (water vapor); hydrogen bonding differs in each state.

Surface tension

Tendency of liquid surfaces to shrink to the smallest area due to cohesive forces.

Capillary action

Movement of water in narrow spaces against gravity due to adhesion and cohesion.

Cohesion

Attraction between water molecules caused by hydrogen bonding.

Adhesion

Attraction of water molecules to other surfaces via hydrogen bonds.

Moderation of temperature

Water's ability to stabilize temperature due to high heat capacity and heat of vaporization.

Hydration/Hydration shell

Sphere of water molecules surrounding and stabilizing dissolved ions or polar molecules.

Solvent of life

Water's ability to dissolve a wide range of substances due to its polarity.

pH

Scale that measures hydrogen ion concentration; lower pH is more acidic, higher pH is more basic.

Acid

Substance that donates H+ ions in solution.

Base

Substance that accepts H+ or donates OH- to solution.

Buffer

Weak acid–base pair that minimizes changes in pH by binding or releasing H+.

Molarity

Concentration defined as moles of solute per liter of solution (M = mol/L).

Mole

6.023 x 10^23 entities; the amount of substance that contains that many particles.

Backbone of life (Carbon)

Carbon forms the backbone of the four major biomolecules: proteins, carbohydrates, lipids, and nucleic acids.

Hydrocarbons

Organic compounds made of carbon and hydrogen; mostly nonpolar and energy-rich; common in larger biomolecules.

Functional group

Specific group of atoms within a molecule that imparts characteristic chemical reactions.

Hydroxyl (–OH)

Polar group found in alcohols and sugars; increases solubility.

Carbonyl (C=O)

Group with a _ bond; aldehydes (terminal) and ketones (internal); polar and hydrophilic.

Carboxyl (–COOH)

Acidic group common in fatty acids and amino acids; can donate a proton.

Sulfhydryl (–SH)

Group found in some amino acids; forms disulfide bonds that stabilize protein structure.

Amino (–NH2)

Group in amino acids; acts as a base; polar and hydrophilic.

Phosphate (–OPO3^2-)

Found in nucleotides, phospholipids, and ATP; highly polar due to negative charge.

Methyl (–CH3)

Nonpolar group that is hydrophobic; influences gene expression and lipid behavior.

Enantiomer

Non-superimposable mirror-image isomers (chiral) with potential biological differences.

Structural isomer

Compounds with the same formula but different covalent arrangement of atoms.

Geometric (cis/trans) isomer

Isomers differing in the orientation around a double bond.

Chiral center

Carbon atom bonded to four different groups, leading to non-superimposable mirror images.