2.1 Atoms, Isotopes, Ions, and Molecules: The Building Blocks Flashcards
Isotopes
one or more forms of an element that have different numbers of neutrons
Elements
unique substances that cannot be broken down into smaller substances
Nucleus
core of an atom; contains protons and neutrons
Neutron
uncharged particle that resides in the nucleus of an atom
Proton
positively charged particle that resides in the nucleus of an atom
Electron
negatively charged subatomic particle that resides outside of the nucleus in the electron orbital
Atomic Number
number of protons in an atom
Mass Number
total number of protons and neutrons in an atom
Atomic Mass
calculated mean of the mass number for an element’s isotopes
Periodic Table
organizational chart of elements (118 elements; 98 naturally occurring)
Chemical Reactivity
the ability to combine and to chemically bond with each other
Octet Rule
atoms are most stable when they hold 8 electrons in their outermost shell
Valence Shell
outermost shell of an atom
Inert Gases
element with filled outer electron shell that is unreactive with other atoms
Ions
atom or chemical group that does not contain equal numbers of protons and electrons
Electron Orbitals
how electrons are spatially distributed surrounding the nucleus
Electron Configuration
arrangement of electrons in an atomic shell
Chemical Bonds
interaction between two or more of the same or different atoms that result in molecules
Chemical Reaction
process leading to the rearrangement of atoms in molecules
Reactants
molecule found of the left side of a chemical equation
Products
molecule found on the right side of a chemical equation
Balanced Chemical Equation
Statement of a chemical reaction with the number of each type of atom equalized for both the products and reactants
Compounds
substance composed of molecules consisting of atoms of at least two different elements
Reversible Reactions
bi-directional; products may turn into reactants if concentration is great enough
Irreversible Reactions
unidirectional; forms products
Equilibrium
steady state of relative reactant and product concentration in reversible chemical reactions in a closed system
Law of Mass Action
chemical law stating that the rate of reaction is proportional to the concentration of the reacting substances
Cation
positive ion formed by an atom losing one or more electrons
Anion
negative ion formed by an atom gaining one or more electrons
Electron Transfer
movement of electrons from one element to another
Ionic Bonds
chemical bond that forms between ions with opposite charges
Electrolytes
ion necessary for nerve impulse conduction, muscle contractions, and water balance
Covalent Bonds
bond formed when electrons are shared between atoms
Polar
unequally shared electrons
Nonpolar
equally shared electrons
Electronegativity
ability of some elements to attract electrons (often of hydrogen atoms), acquiring partial negative charges in molecules and creating partial positive charges on the hydrogen atoms
Hydrogen Bond
weak bond between slightly positive hydrogen atoms and slightly negative atoms in other molecules
van der Waals interactions
very weak interaction between molecules due to temporary changes attracting atoms that are close together
