Download Chapter 2 Vocabulary

Vocabulary Notes
Intro. To Chemistry
(Part 2)
Atoms
The smallest particles of an element that retain the chemical identity of
the element.
Subatomic
particles
Particles that make up an atom.
Cathode rays
Streams of electrons that are produced when a high voltage is applied to
electrodes in an evacuated tube.
Radioactivity
Spontaneous disintegration of an unstable atomic nucleus with
accompanying emission of radiation.
Nucleus
Very small, positively charged dense region of an atom where most of the
mass is found.
Protons
Positively charged subatomic particles.
Neutrons
Neutral subatomic particles.
Electrons
Negatively charged subatomic particles.
Electronic
charge
The electronic charge carried by an electron, equal to 1.602 x 10-19 C.
Atomic mass unit
A unit based on the value of exactly 12 amu for the mass of the isotope
of carbon that has six protons and six neutrons in the nucleus.
Atomic number
The number of protons in the nucleus of an atom of an element.
Mass number
The sum of the number of protons and neutrons in the nucleus of a
particular atom.
Isotopes
Atoms of the same element containing different numbers of neutrons
and therefore having different masses.
Atomic weight
The average mass of the atoms of an element in atomic mass units (amu);
it is numerically equal to the mass of one mole of the element.
Mass
spectrometer
An instrument used to measure the precise masses and relative amount
of atomic and molecular ions.
Periodic table
The arrangement of elements in order of increasing atomic number, with
elements having similar properties placed in vertical columns.
Group
Elements that are in the same column of the periodic table; elements
within the same group or family exhibit similarities in their chemical
behavior.
Period
The row of elements that lie in a horizontal row in the periodic table.
Metallic
elements
(metals) Elements that are usually solid at room temperature, exhibit
high electrical and heat conductivity, and appear lustrous. Most of the
elements in the periodic table are metals.
Molecules
A chemical combination of two or more atoms.
Molecular
compounds
A compound made up of molecules.
Diatomic
molecule
A molecule composed of only two atoms.
Chemical formula
A notation that used chemical symbols with numerical subscripts to
convey the relative proportions of atoms of the different elements in a
substance.
Structural
formulas
A formula that shows not only the number of kinds of atoms in the
molecule but also the arrangements of the atoms.
Cations
A positively charged ion.
Anions
A negatively charged ion.
Ionic compounds
A compound composed of cations and anions.
Polyatomic ions
An electrically charged group of two or more atoms.
Chemical
nomenclature
The rules used in naming substances.
Organic
chemistry
The study of carbon containing compounds, typically containing carboncarbon bonds.
Hydrocarbons
Compounds composed on only carbon and hydrogen.
Alkanes
Compounds of carbon and hydrogen containing only carbon-carbon single
bonds.
Alcohol
An organic compound obtained by substituting a hydroxyl group (-OH) for
a hydrogen on the hydrocarbon.