Chapter 8 Then Atom

Question 1

Absorption lines

Answer 1

A dark line in an absorption spectrum that corresponds to the absorbed wavelength of light.

Question 2

Alkali metals

Answer 2

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.

Question 3

Alkaline earth metals

Answer 3

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.

Question 4

Alpha particles

Answer 4

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.

Question 5

Atomic number

Answer 5

The number of protons in the nucleus, which determines the nuclear charge, and therefore the chemical identity of the atom.

Question 6

Atomism

Answer 6

The hypothesis that for each chemical element there is a corresponding species of indivisible objects called atoms.

Question 7

Bohr atom

Answer 7

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.

Question 8

Electron

Answer 8

Tiny, negatively charged particles that surround a positively charged nucleus of an atom.

Question 9

Electron shells

Answer 9

A specific energy level in an atom that can be filled with a predetermined number of electrons.

Question 10

Elements

Answer 10

A material made from a single type of atom, which cannot be broken down any further.

Question 11

Elements

Answer 11

A material made from a single type of atom, which cannot be broken down any further.

Question 12

Excited states

Answer 12

All energy levels of an atom above the ground state.

Question 13

Ground state

Answer 13

The lowest energy level of an atom.

Question 14

Ions

Answer 14

An atom that has an electrical charge, from either the loss or gain of an electron.

Question 15

Laser

Answer 15

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.

Question 16

Molecule

Answer 16

A cluster of atoms that bond together; the basic constituent of many different kinds of material.

Question 17

Noble gases

Answer 17

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

Question 18

Nucleus

Answer 18

(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.

Question 19

Pauli exclusion principle

Answer 19

A statement that says no two electrons can occupy the same state at the same time.

Question 20

Periodic table of the elements

Answer 20

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.

Question 21

Photon

Answer 21

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.

Question 22

Proton

Answer 22

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.

Question 23

Pumping

Answer 23

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.

Question 24

Quantum jump

Answer 24

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.

Question 25

Quantum leap

Answer 25

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.

Question 26

Quantum mechanics

Answer 26

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.

Question 27

Spectroscopy

Answer 27

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.

Question 28

Spectrum

Answer 28

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.