Chapter 4;The Chemical Basis of Life Flashcards
Element
Pure substance that cannot be broken down into other substances by chemical/physical means
Matter
Anything that occupies space and had mass
Trace element
Element critical to health that makes up less than .01% of body mass
Compound
Substance containing two or more elements chemically combined in a fixed ratio
Atom
Smallest particle of an element
Proton
Subatomic particle with a single unit of positive electric charge
Electron
Subatomic particle with a single unit of negative electric charge
Neutron
Subatomic particle that has no charge
Nucleus (in an atom)
Central core of an atom, contains protons and neutrons
Chemical reactivity
Tendency to undergo chemical changes
Ionic bond
Chemical bond that occurs when an atom transfers electrons to another atom
Ion
Atom that has become electrically charged as a result of gaining or losing electrons
Covalent bond
Chemical bond that forms when two atoms share electrons
Molecule
Two or more atoms held together by covalent bonds
Chemical reaction
The breaking of old and formation of new chemical bonds that result in new substances
Reactant
Starting material for chemical reaction
Product
Material created as the result of a chemical reaction
Polar molecule
Molecule in which opposite ends have opposite electric charges
Hydrogen bond
Bond created by the weak attraction of a slightly positive hydrogen atom to a slightly negative portion of another molecule
Cohesion
Tendency of molecules of the same kind to stick to one another
Adhesion
Attraction between unlike molecules
Thermal energy
Total amount of energy associated with the random movement of atoms and molecules in a sample of matter
Acid
Compound that donates H+ ions to an aqueous solution and measures less than seven on the pH scale
Base
Compounds that removes H+ ions from an aqueous solution and that measures more than seven on the pH scale
