click below
click below
Normal Size Small Size show me how
Ap Biology Ch. 2
The Chemical Context of Life
Question | Answer |
---|---|
matter | Anything that takes up space and has mass |
element | Any substance that cannot be broken down to any other substance |
compound | A substance consisting of two or more elements in a fixed ration |
trace element | An element indispensable fo life but required in extremely minute amounts |
atom | The smallest unit of matter that retains the properties of an element |
neutron | An electrically neutral particle (a particle having no electrical charge), found in the nucleus of an atom |
proton | A subatomic particle with a single positive electrical charge, found in the nucleus of an atom |
electron | A subatomic particle with a single negative charge. One or more electrons move around the nucleus of an atom |
atomic nucleus | An atom's central core, containing protons and neutrons |
dalton | A measure of mass for atoms and subatomic particles |
atomic number | The number of protons in the nucleus of an atom, unique for each element and designated by a subscript to the left of the chemical symbol |
mass number | The sum of the number of protons and neutrons in an atom's nucleus |
atomic mass | The total mass of an atom, which is the mass in grams of one mole of the atom |
isotope | One of several atomic forms of an element, each containing a different number of neutrons and thus differing in atomic mass |
radioactive isotope | An isotope (an atomic form of a chemical element) that is unstable; the nucleus decays spontaneously, giving off detectable particles and energy |
energy | The capacity to do work (to move matter against an opposing force) |
potential energy | The energy stored by matter as a result of its location or spatial arrangement |
energy level | Any of several different states of potential energy for electrons in an atom |
electron shell | An energy level represented as the distance of an electron from the nucleus of an atom |
valence electron | An electron in the outermost electron shell |
valence shell | The outermost energy shell of an atom, containing the valence electrons involved in the chemical reactions of that atom |
orbital | The three-dimensional space where an electron is found 90% of the time |
chemical bond | An attraction between two atoms, resulting from a sharing of outer-shell electrons or the presence of opposite charges on the atoms. The bonded atoms gain complete outer electron shells |
covalent bond | A type of strong chemical bond in which two atoms chare one or more pairs of valence electrons |
molecule | Two or more atoms held together by covalent bonds |
single bond | a pair of shared electrons (a single covalent bond) |
structural formula | A type of molecular notation in which the constituent atoms are joined by lines representing covalent bonds |
molecular formula | A type of molecular notation indicating only the quantity of the consituent atoms |
double bond | two pairs of shared electrons (a double covalent bond) |
valence | The bonding capacity of an atom, generally equal to the number of unpaired electrons in the atom's outermost shell |
electonegativity | The attraction of an atom for the electrons of a covalent bond |
nonpolar covalent bond | A type of covalent bond in which electrons are shared equally between two atoms of similar electronegativity |
polar covalent bond | A covalent bond between atoms that differ in electronegativity. The shared electrons are pulled closer to the more electronegative atom, making it slightly negative and the other atom slightly positive. |
ion | An atom that has gained or lost electrons, thus acquiring a charge |
cation | An ion with a positive charge, produced by the loss of one or more electrons |
anion | A negatively charged ion |
ionic bond | A chemical bond resulting from the attraction between oppositely charged ions |
ionic compound | A compound resulting from the formation of an ionic bond; also called a salt |
salt | A compound resulting from the formation of an ionic bond; also called an ionic compound |
hydrogen bond | A type of weak chemical bond formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule |
van der Waals interactions | Weak attractions between molecules or parts of molecules that are brought about by localized charge fluctuations |
chemical reaction | A process leading to chemical changes in matter; involves tha making and/or breaking of chemical bonds |
reactant | A starting material in a chemical reactions |
product | An ending material in a chemical reaction |
chemical equilibrium | In a reversible chemical reaction, the point at which the rate of the forward reaction equals the rate of the reverse reaction |