Chapter 2: Vocabulary Flashcards
matter
anything that occupies space and has mass
element
a substance that cannot be broken down to other substances by chemical means. Scientists recognize 92 chemical elements occurring in nature
trace elements
an element that is essential for the survival of an organism but only in minute quantities
compound
a substance containing @ or more elements in a fixed ratio. For example, table salt (NaCl) consists of one atom of the element sodium (Na) for every atom of chlorine (Cl)
atom
the smallest unit of matter that retains the properties of an element
proton
A subatomic particle with a single positive electrical charge, found inside the nucleus of an atom
neutron
an electrically neutral particle (a particle having no electrical charge) found in the nucleus of an atom
electron
A subatomis particle with a single negative electrical charge. One or more electrons move around the nucleus of an atom
nucleus
(!) An atom’s central coe, containing protons and neutrons (2) The genetic control center of a eukaryotic cell.
atomic number
the number of protons in each atom of a particular element
atomic mass
the approximate total mass of an atom; also called atomic weight. Given as w whole number, the atomic mass approximately equals the mass number
mass number
the sum of the number of protons and neutrons in an atom’s nucleus
isotipe
a variant form of an atom. isotopes of an element have the same number of protons but different numbers of neutrons
radioactive isotope
an isotope whose nucleus decays spontaneously, giving off particles and energy
electron shell
an energy level representing the distance of an electron from the nucleus of the atom
chemical bond
an attraction between 2 atoms resulting from a sharing of outer-shell electrons or the prescence of opposite charges on the atoms/ The bonded atoms gain complete outer electron shells
ion
an atom or molecule that has gained or lost 1 or more electrons, thus acquiring an electrical charge
ionic bond
an attraction between two ions with opposite electrical charges. The electrical attraction of the opposite charges holds the ions together
salt
a compound resulting from the formation of ionic bonds; also called an ionic compound
molecule
a group of 2 or more atoms held together by covalent bonds
double bond
a type of covalent bond in which 2 atoms share 2 pairs of electrons; symbolized by a pair of lines between the bonded atroms
electronegativity
the tendency for an atom to pull electrons towards itselg
plar covalent bond
an attraction between atoms that share electrons unequally because the atoms differ in electronegativity. the shared electrons are pulled closer to the more electronegative atom, making it partially negative and the other atom partially positive
polar molecule
a molecule containing polar covalent bonds
hydrogen bond
a type of weak chemical bond formed when the partially positive hydrogen atom participating in a polar covalent bond in one molecule is attracted to the partially negative atom participating in a polar covalent bond in another molecule ( or in another part of the same macromolecule)
surface tension
a measure of how difficult it is to stretch or break the surface of a liquid
heat
thermal energy; the amount of energy associated with the movement of atoms and molecules in a body of matter. heat is energy in its most random fotrm
temperature
a measure of the intensity of heat, reflecting the average kinetic energy or speed of molecules
solution
a liquid consisting of a homogeneous mixture of 2 or more substances, consisting of a dissolving agent, called the solvent, and a substance that is dissolved, called the solute
solute
a substance that is dissolved in a solution
solvent
the dissolving agent in a solution. water is the most versatile known solvent.
aqueous solution
a solution in which water is the solvent
acid
a substance that increases the hydrogen ion concentration in a solution
base
a substance that decreases the hydrogen ion (H+) concentration in a solution
buffer
a chemical substance that resists changes in pH by accepting hydrogen ions forom or donating hydrogen ions to solutions
pH scale
the measure of relative acidity of a solution, ranging in value from 0 (most acidic) to 14 (most basic). The letters pH stand for potential hydrogen and refer to the concentration of hydrogen ions (H+)
acid precipitation
rain, snow, sleet, hail, drizzle and so on with a pH below 5.6. Acid precipitation can damage or destroy organisms by acidifying lakes, streams, and possibly land habitats
chemical reaction
a process leading to changes in the composition of matter; involves the making and/or breaking of chemical bonds
reactants
a skating material in a chemical reaction
product
an ending material in a chemical reaction
covalent bond
an attraction between atoms that share one or more pairs of outer shell electrons; symbolized by a single line between the atoms
non polar covalent bond
an attraction between atonst that share one or more electrons equally because the atoms have similar electronegativity
cohesion
tha attraction between molecules of the same kind
