Cambell Biology - Chapter 2

Element
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Terms in this set (43)
Element
substance that cannot be broken down to other substances by chemical reactions
Compound
substance consisting of two or more different elements combined in fix ratio
Essential elements
elements that organisms need to live a healthy life and reproduce (naturally)
Trace elements
required by an organism in only minute quantities (SUCH AS IRON)
Atom
smallest unit of matter that still retains the properties of an element
Image: Atom
Neutrons
electrically neutral
Image: Neutrons
Protons
positive charge
Image: Protons
Electron
negative charge
Image: Electron
Atomic nucleus
protons and neutrons packed together in a tight core; center of an atom;
Image: Atomic nucleus
Dalton
atoms and subatomic particles, the unit of measurement used is...
Image: Dalton
Atomic numberthe number of protons that can be found as a subscript of the elementMass numberthe number of neutrons, which is the sum of protons and neutrons in the nucleus of the atomAtomic masstotal mass of the atomIsotopesdifferent atomic forms where an element has the same number of protons but some atoms have more neutrons than other atoms of the same element WHICH MEANS MORE MASSRadioactive isotopenucleus delays spontaneously, giving off particles of energyElectron shellsElectrons that occur in energy levelsChemical bondsWhen the atom shares, donates, or receive electrons, which results in attractions between atoms creating the bond.Ionic BondTwo ions with opposite charges attract each other and then holds two ions togethercovalent bondthis results when atoms share outer -shell electronsmoleculethis is formed when atoms are held together by covalent bondselectronegativitythe attraction (pull) for shared electronsnonpolar covalent bondsIn molecules of only one element, the pull toward each atom is equal, because each atom has the same electronegativity, forming bondspolar covalent bondUnequal sharing of electrons. Electrons of this bond are pulled closer to the more electronegative atom, such as the oxygen in H2Opolar moleculesmolecules wth this unequal distribution of chargeshydrogen bondsAttraction between a slightly positive hydrogen atom and a slightly negative atom. H20 and DNAsurface tensiona measure of how difficult it is to break the surface of a liquidheatthe energy associated with the movement of atoms and molecules in mattertemperaturemeasures the intensity of heatsolutiona liquid consisting of a uniform mixture of two or more substancessolventthe dissolving agent in a solutionsolutethe substance that is dissolved in a solutionacidschemicals that can contribute H+ to a solution (not water)basesthe chemicals that accept hydrogen ions and remove them from the solutionpH scaleis used to determine whether a solution is acidic or basicchemical reactionthe formation of things from individual elementsreactantsthings that contribute to the final productproductthe final element / thingVan der Waals interactionsOccur between transiently positive and negative regions of molecules. ex:geckoorbitalsThe area of an atom that an electron is most likely to be in, given its amount of energy.valence electronselectrons in the outermost shellelectron shellAn energy level representing the distance of an electron from the nucleus of an atom.chemical bondsthe attractive forces that hold atoms togetherchemical equilibriumthe point at which the reactions offset one another exactly a state of balance in which the rates of the forward and reverse reactions are equal