Lecture 2: Key Concepts in Chemistry and Biochemistry

Vocabulary flashcards covering elements, atomic structure, bonds, reactions, water properties, acids/bases/pH, dehydration/hydrolysis, and biomolecules (carbohydrates, lipids, proteins).

chemical element

a pure substance that cannot be broken down into simpler substances by ordinary chemical methods.

major elements in the body

the four most common elements: oxygen, carbon, hydrogen, and nitrogen.

atom

a cluster of protons, neutrons, and electrons.

nucleus

the central region containing protons and neutrons; positively charged.

proton

a positively charged subatomic particle in the nucleus.

neutron

a neutral subatomic particle in the nucleus.

electron

a negatively charged subatomic particle that orbits the nucleus.

atomic number

the number of protons in an atom; in a neutral atom, also the number of electrons.

mass number

the sum of protons and neutrons in an atom.

isotope

atoms of the same element that have the same number of protons and electrons but different numbers of neutrons.

valence shell

the outer electron shell of an atom.

octet rule

atoms tend to have 8 electrons in their valence shell (except shell 1, which has 2).

molecule

a group of two or more atoms bonded together chemically.

compound

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

compound vs molecule relationship

a compound is a type of molecule; a molecule is not necessarily a compound.

solution

a homogeneous mixture with the same composition throughout.

colloid

a homogeneous substance with large molecules dispersed in another substance; particles are larger than a true solution but remain suspended.

suspension

a heterogeneous mixture with large solutes that tend to settle out.

covalent bond

bond formed by sharing electrons between atoms.

nonpolar covalent bond

electrons are shared equally between atoms.

polar covalent bond

electrons are shared unequally due to differences in electronegativity.

ionic bond

transfer of electrons between atoms creating charged ions that attract.

hydrogen bond

a weak attraction between a hydrogen atom covalently bonded to a very electronegative atom and another electronegative atom.

water

the most abundant inorganic compound in living matter; polar solvent with high heat capacity and heat of vaporization; major transport medium and reactant in many reactions.

acid

a substance that releases hydrogen ions (H+); a proton donor.

base

a substance that takes up a hydrogen ion (H+); a proton acceptor.

pH

a measure of H+ concentration; high pH is basic; low pH is acidic.

dehydration synthesis

monomers are joined by removal of OH from one monomer and H from the other at the bond formation site.

hydrolysis

monomers are released by the addition of a water molecule; water is added to break bonds.

monomer

the building block of polymers; a single unit.

amino acid

the building blocks of proteins; 20 common types; differ by their R group.

peptide bond

bond linking amino acids in proteins.

protein

a large, complex biological molecule made of one or more long chains of amino acids linked by peptide bonds.

carbohydrate

a biomolecule containing carbon, hydrogen, and oxygen; typical H:O ratio about 2:1; main energy source.

monosaccharide

one sugar.

disaccharide

two sugars.

polysaccharide

many sugars.

glycogen

a storage polysaccharide stored in skeletal muscle and liver.

phospholipid

lipid with a hydrophilic head and hydrophobic tails; chief component of cell membranes.

cholesterol

a lipid component of cell membranes; starting molecule for synthesis of steroids.