Chapter 8 Then Atom Flashcards
Absorption lines
A dark line in an absorption spectrum that corresponds to the absorbed wavelength of light.
Alkali metals
Elements that are highly reactive, such as lithium, sodium, and potassium; listed in the far left-hand column of the periodic table of elements. These elements possess one valence electron.
Alkaline earth metals
Elements that combine with oxygen in a one-to-one ratio and form colorless solid compounds with high melting temperatures. Listed in the second column in the periodic table of elements: beryllium, magnesium, calcium, and others. These elements possess two valence electrons.
Alpha particles
A subatomic radioactive particle, made of two protons and two neutrons, used by Ernest Rutherford in a well-known experiment in which the nucleus was discovered.
Atomic number
The number of protons in the nucleus, which determines the nuclear charge, and therefore the chemical identity of the atom.
Atomism
The hypothesis that for each chemical element there is a corresponding species of indivisible objects called atoms.
Bohr atom
A model of the atom, developed by Niels Bohr in 1913, in which electrons exist only in allowed energy levels. In these energy levels, the electrons maintain fixed energy for long periods of time, without giving off radiation.
Electron
Tiny, negatively charged particles that surround a positively charged nucleus of an atom.
Electron shells
A specific energy level in an atom that can be filled with a predetermined number of electrons.
Elements
A material made from a single type of atom, which cannot be broken down any further.
Elements
A material made from a single type of atom, which cannot be broken down any further.
Excited states
All energy levels of an atom above the ground state.
Ground state
The lowest energy level of an atom.
Ions
An atom that has an electrical charge, from either the loss or gain of an electron.
Laser
An instrument that uses a collection of atoms, energy, and mirrors to emit photons that have wave crests in exact alignment. The instrument name is the acronym for light amplification by stimulated emission of radiation.
Molecule
A cluster of atoms that bond together; the basic constituent of many different kinds of material.
Noble gases
Elements listed in the far righthand column of the periodic table of elements, including helium, argon, and neon, which are odorless, colorless, and slow to react
Nucleus
(1) The very small, compact object at the center of an atom; made up primarily of protons and neutrons. (2) A prominent structure in the interior of a cell that contains the cell’s genetic material—the DNA—and controls the cell’s chemistry.
Pauli exclusion principle
A statement that says no two electrons can occupy the same state at the same time.
Periodic table of the elements
An organizational system, first developed by Dmitri Mendeleev in 1869, now listing more than 110 elements by atomic weight (in rows) and chemical properties (in columns). The pattern of elements in the periodic table reflects the arrangement of electrons in their orbits.
Photon
A particle-like unit of light, emitted or absorbed by an atom when an electrically charged electron changes state. The form of a single packet of electromagnetic radiation.
Proton
One of two primary building blocks of the nucleus; with a positive electrical charge of 11 and a mass 1.672643310224g approximately equal to that of the neutron.
Pumping
The process in a laser that adds energy to the system from the outside to return atoms continuously to their excited states so that coherent photons can be produced.
Quantum jump
A process by which an electron changes its energy state without ever possessing an energy intermediate between the original and the final energy state; also known as a quantum jump.
Quantum leap
A process by which an electron changes its energy state without ever possessing an energy intermediate between the original and the final energy state; also known as a quantum jump.
Quantum mechanics
The branch of science that is devoted to the study of the motion of objects that come in small bundles, or quanta, which applies to the subatomic world.
Spectroscopy
The study of emission and absorption spectra of materials in order to discover the chemical makeup of a material; a standard tool used in almost every branch of science.
Spectrum
The characteristic signal from the total collection of photons emitted by a given atom that can be used to identify the chemical elements in a material; the atomic fingerprint.
