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47 terms

Weaver Bio Chapter 2

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atom
the basic unit of matter
nucleus
the center of an atom, made up of protons and neutron
proton
the positively charged particle in an atom
neutron
the particle of an atom that has no charge
electron
the negatively charged particle in an atom
element
a pure substance that contains ony one kind of atom
compound
a substance that is made of more than one kind of element, combimed in sepcific proportions
atomic number
the number of protons in an atom
mass number
the total mass of the protons and neutrons in a particular atom
isotopes
two atoms of the same element with different mass numbers (same number of protons, different number of neutrons)
ionic bond
a bond that is formed when one atom gives electrons to another atom
covalent bond
a bond that is formed when atoms share electrons
atomic mass
the average mass of all isotopes of a given element
valence electron
an electron in an atom's outer energy level, where it can take part in a reaction with other atoms
ion
an atom or molecule that has a charge because it has gained or lost electrons
hydrogen bond
a weak attraction between a hydrogen atom and another atom; the way water molecules bond
molecule
the particle created when atoms bond together, with either similar or different kinds of atoms
polar
an arrangement of a molecule where one side has a positive charge and the other has a negative charge
cohesion
the attraction between molecules of the same substance
adhesion
the attraction between molecules of different substances
mixture
a material made of two or more substances that are not chemically combined
solution
a material made of at least one substance that has dissolved another, so that all the components are equally distributed
solute
the material that is dissolved in a solution
solvent
the material that dissolves another substance in a solution
pH
a measure of how acidic or basic a substance is (the concentration of H+ ions)
acid
a substance with a pH lower than 7; forms H+ ions in a solution
base
a substance with a pH higher than 7; forms OH- ions in a solution
buffers
weak acids or bases that react with strong acids or bases to prevent a sudden change in pH
monomer
a small compound that joins with others to make a polymer
polymer
a macromolecule formed by joining many monomers
carbohydrate
compounds made of carbon, hydrogen, and oxygen, usually in the ratio of 1:2:1
monosaccharide
a simple suger made of one molecule
starch
a substance that forms when sugars join in long chains
polysaccharide
a macromolecule that stores sugars in the body; formed by joining many monosaccharides
lipid
an energy-storing family of molecules made mostly of carbon and hydrogen, and which are not soluble in water; "fats"
nucleic acid
macromolecules made of nucleotides; 2 kinds: DNA and RNA
nucleotide
the building block of a nucleic acid
protein
macromolecules made of combinations of amino acids
amino acid
the building block of a protein
chemical reaction
a process that changes one set of chemicals into another
reactants
the chemicals that enter an chemical reaction
products
the chemicals that result from a chemical reaction
activation energy
the energy needed to get a reaction started
catalyst
a substance that speeds up the rate of a chemical reaction by lowering the activation energy
enzyme
a protein that acts as a catalyst
substrate
the reactants in a chemical reaction that uses an enzyme as a catalyst
van der Waals forces
the weak attraction between the oppositely charged regions of nearby molecules