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34 terms

Chapter 2: The Chemistry of Life

Biology Chapter 2
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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