Chapter 2 Flashcards
MATTER
Anything that occupies space and has mass.
ELEMENT
A substance that cannot be broken down to other substances by chemical means.
COMPOUND
A substance containing two 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).
TRACE ELEMENTS
an element that occurs at very small quantities in the body but is nonetheless important for many biological processes
ATOM
The smallest unit of matter that retains the properties of an element.
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 electrical charge. One or more electrons move around the nucleus of an atom.
REACTANTS
a substance that takes part in and undergoes change during a reaction.
SURFACE TENSION
A measure of how difficult it is to stretch or break the surface of a liquid. Water has a high surface tension because of the hydrogen bonding of surface molecules.
SOLUTE
A substance that is dissolved in a solution.
BUFFERS
a solution that resists a change in pH when acids or bases are added.
NEUTRON
A subatomic particle having no electrical charge, found in the nucleus of an atom.
NUCLEUS
(1) An atom’s central core, containing protons and neutrons. (2) The organelle of a eukaryotic cell that contains the genetic material in the form of chromosomes, made of chromatin.
ATOMIC NUMBER
The number of protons in each atom of a particular element.
MASS NUMBER
The sum of the number of protons and neutrons in an atom’s nucleus.
ATOMIC MASS
The total mass of an atom; also called atomic weight. Given as a whole number, the atomic mass approximately equals the mass number.
ISOTOPES
one of two or more atoms with the same atomic number but with different numbers of neutrons
RADIOACTIVE ISOTOPE
An isotope whose nucleus decays spontaneously, giving off particles and energy.
PRODUCT
An ending material in a chemical reaction.
THERMAL ENERGY
Kinetic energy due to the random motion of atoms and molecules; energy in its most random form.
EVAPORATIVE COOLING
The process in which the surface of an object becomes cooler during evaporation, a result of the molecules with the greatest energy changing from the liquid to the gaseous state.
AQUEOUS SOLUTION
A solution in which water is the solvent.
OCEAN ACIDIFICATION
Process by which the pH of the ocean is lowered (made more acidic) when excess atmospheric CO2 dissolves in seawater.
ELECTRON SHELLS
a grouping of electrons surrounding the nucleus of an atom
CHEMICAL BONDS
an electrical force linking atoms
IONIC BONDS
a chemical bond in which one atom loses an electron to form a positive ion and the other atom gains an electron to form a negative ion
COVALENT BOND
A type of strong chemical bond in which two atoms share one or more pairs of valence electrons.
MOLECULE
Two or more atoms held together by covalent bonds. GLOSSARY
ELECTRONEGATIVITY
The attraction of a given atom for the electrons of a covalent bond.
NON POLAR COVALENT BONDS
A bond between 2 nonmetal atoms that have the same electronegativity and therefore have equal sharing of the bonding electron pair
COHESION
The sticking together of molecules of the same kind, often by hydrogen bonds.
ADHESION
The attraction between different kinds of molecules.
HEAT
Thermal energy in transfer from one body of matter to another.
TEMPERATURE
A measure in degrees of the average thermal energy of the atoms and molecules in a body of matter.
SOLUTION
A liquid that is a homogeneous mixture of two or more substances.
SOLVENT
The dissolving agent of a solution. Water is the most versatile solvent known.
ACID
A substance that increases the hydrogen ion (H+) concentration in a solution.
BASE
A substance that decreases the hydrogen ion (H+) concentration in a solution.
PH SCALE
A measure of the 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+).
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.
IONIC BONDS
a chemical bond in which one atom loses an electron to form a positive ion and the other atom gains an electron to form a negative ion
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 (or in another region of the same molecule).
POLAR MOLECULE
A molecule containing polar covalent bonds and having an unequal distribution of charges in different regions of the molecule.
CHEMICAL REACTIONS
(chemistry) a process in which one or more substances are changed into others
