Chapter 2 Key Terms Flashcards
A given compound always contains exactly the same proportion of elements by mass
Law of definite proportions
Mass is neither created nor destroyed
Law of conservation of mass
When 2 elements form a series of compounds, the ratios of the masses of the second element that combine with 1 g of the first element can always be reduced to small whole numbers
Law of multiple proportions
The weighted average mass of the atoms in a naturally occurring element
Atomic mass (atomic weight)
At the same temperature and pressure, equal volumes of different gases contain the same number of particles
Avogadro’s hypothesis
Tube in which “rays” (stream of electrons) emanate from the negative electrode (cathode)
Cathode-ray tube
Negatively charged particle that moves around the nucleus of an atom
Electron
The spontaneous decomposition of a nucleus to form a different nucleus
Radioactivity
Atom with a dense center of positive charge with electrons moving around the nucleus at a distance that is large relative to the nuclear radius
Nuclear atom
Small, dense center of positive charge in an atom
Nucleus
Positively charged particle in an atomic nucleus
Proton
Particle in the nucleus with the same mass as a proton with no charge
Neutron
Atoms with the same number of protons but different numbers of neutrons
Isotopes
Number of protons in the nucleus of an atom
Atomic number
Total number of protons and neutrons in the nucleus of an atom
Mass number
The force, or more accurately, the energy, that holds two atoms together in a compound
Chemical bond
A type of bond in which electrons are shared by atoms
Covalent bond
A bonded collection of 2 or more atoms of the same or different elements
Molecule
The representation of a molecule in which the symbols for the elements are used to indicate the types of atoms present and subscripts are used to show the relative number of atoms
Chemical formula
The representation of a molecule in which the relative positions of the atoms are shown and the bonds are indicated by lines
Structural formula
A model of a molecule showing the relative sizes of the atoms and their relative orientations
Space-filling model
A molecular model that distorts the sizes of atoms but shows bond relationships clearly
Ball-and-stick model
An atom or a group of atoms that has a net positive or negative charge
Ion
A positive ion; formed by loss of an electron
Cation
A negative ion; formed by gain of an electron
Anion
The electrostatic attraction between oppositely charged ions
Ionic bond
A solid containing cations and anions that dissolves in water to give a solution containing the separated ions which are mobile and thus free to conduct electricity
Ionic solid (salt)
An ion containing a number of atoms
Polyatomic ion
A chart showing all the elements arranged in columns with similar chemical properties
Periodic table
An element that gives up electrons relatively easily to form positive ions and is lustrous, malleable, ductile, and a good conductor of heat and electricity
Metal
An element not exhibiting metallic characteristics; chemically, typically accepts electrons to form negative ions
Nonmetal
A vertical column of elements having the same valence electron configuration and showing similar chemical properties
Group (family)
Group 1A metals; very active elements that readily form ions with a 1+ charge when they react with nonmetals
Alkali metals
Group 2A metals; all form ions with a 2+ charge with nonmetals
Alkaline earth metals
Group 7A elements; all form diatomic molecules and react with metals to form salts containing ions with a 1- charge
Halogens
Group 8A elements; all exist under normal conditions as monatomic (single-atom) gases and have little chemical reactivity
Noble gases
Horizontal row of elements in the periodic table
Period
Compounds composed of 2 elements
Binary compounds
Compounds composed of 2 elements and contain a positive ion (cation) and a negative ion (anion)
Binary ionic compounds
Compounds formed between 2 nonmetals
Binary covalent compounds
Anions that contain an atom of a given element and different #s of oxygen atoms
Oxyanions
A substance that produces hydrogen ions in solution; a proton donor
Acid
