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41 terms

Ch 2: the chemical context of life

CHEMICAL ELEMENTS AND COMPOUNDS -Matter consists of chemical elements in pure form and in combination called compounds -Life requires about 25 chemical elements ATOMS AND MOLECULES -Atomic structure determines the behavior of an element -Atoms combine by chemical bonding to form molecules -Weak chemical bonds play important roles in the chemistry of life -A molecule's biological function is related to its shape -Chemical reactions make and break chemical bonds
STUDY
PLAY
matter
anything that takes up space and has mass
element
any substances that cannot be broken down to any other substance
compound
a substance consisting of two or more elements in a fixed ratio
trace element
an element indispensable for 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 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 elemental symbol
mass number
the sum of the number of protons and neutrons in an atom's nucleus
atomic weight
the total atomic mass, which is the mass in grams of one mole of an 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 delectable 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, electron shell
the different states of potential energy for electrons in an atom/an energy level representing the distance of an electron from the nucleus of an atom
valence electron
the 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 share one pair of valence electrons
molecule
two or more atoms held together by covalent bonds
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 constituent atoms
double covalent bond
a type of covalent bond in which two atoms share two pairs of electrons; symbolized by a pair of lines between the bonded atoms
valence
the bonding capacity of an atom generally equal to the number of unpaired electrons in the atom's outermost shell
electronegativity
the attraction of the 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 type of 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 between oppositely charged ions
ionic compound, salt
compounds resulting from the formation of ionic bonds
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 interaction
weak attractions between molecules or parts of molecules that are brought about localized charge flactuations
reactant
a starting material in a chemical reaction
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