Chapter 2: The Chemistry of Life

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Biology Chapter 2

atoms

the basic unit of matter

electron

a negatively charged particle

isotopes

atoms of the same element that differ in the number of neutrons they contain

radioactive isotopes

their nuclei are unstable and break down at a constant rate of time

compound

a substance formed by the chemical combination of two or more elements in definite proportions

ionic bonds

formed when one or more electrons are transferred from one atom to another

covalent bonds

form when electrons are shared between atoms

molecule

the smallest unit of most compounds

van der Waals forces

when molecules are close together, a slight attraction can develop between the oppositely charged regions of attraction (van der Waals forces)

polar molecule

a molecule in which the charges are unevenly distributed

cohesion

an attraction between molecules of the same substance

adhesion

an attraction between molecules of different substances

mixture

a material composed of two or more elements or compounds that are physically mixed together but not chemically combined

solute

the substance that is dissolved

solvent

the substance that dissolves

suspensions

mixture of water and nondissolved material

pH scale

it ranges from 0-14

acids

they contain higher concentrations of hydrogen ions than pure water and have pH values below 7

basic

they contain lower concentrations of hydrogen ions than pure water and have pH values of above 7

buffers

weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH

monomers

the smaller units of macromolecules

polymers

the larger units of macromolecules (monomers combine to form this)

carbohydrates

compounds made up of carbon, hydrogen, and oxygen atoms

monosaccharides

single sugar molecules

polysaccharides

the large macromolecules formed from monosaccharides

lipids

made mostly of carbon and hydrogen atoms

nucleic acids

macromolecules containing hydrogen, oxygen, nitrogen, carbon, and phosphorus

nucleotides

nucleic acids are polymers assembled from individual monomers know as this.

proteins

macromolecules that contain nitrogen as well as carbon, hydrogen, and oxygen

amino acids

proteins are polymers of molecules called this.

reactants

the elements or compounds that enter into a chemical reaction

activation energy

the energy that is needed to get a reaction started

catalyst

a substance that speeds up the rate of a chemical reaction

enzymes

proteins that act as biological catalysts

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