Chapter 4

Question 1

Atomic mass

Answer 1

The total mass of an atom. The atomic mass of each element presented in the periodic table is the weighted average atomic mass of the various isotopes of that element occurring in nature.

Question 2

Atomic nucleus

Answer 2

The dense - positively charged center of every atom.

Question 3

Atomic number

Answer 3

The number of protons in the atomic nucleus of each atom of a given element.

Question 4

Atomic orbital

Answer 4

A volume of space where an electron is likely to be found 90 percent of the time.

Question 5

Atomic spectrum

Answer 5

The pattern of frequencies of electromag- netic radiation emitted by the energized atoms of an element - considered to be an element’s “fingerprint.”

Question 6

Conceptual model

Answer 6

A representation of a system that helps us predict how the system behaves.

Question 7

Effective nuclear charge

Answer 7

The nuclear charge experienced by outer-shell electrons - diminished by the shielding effect of inner-shell electrons and also by the distance from the nucleus.

Question 8

Electromagnetic spectrum

Answer 8

The complete range of waves - from radio waves to gamma rays.

Question 9

Electron

Answer 9

An extremely small - negatively charged subatomic particle found outside the atomic nucleus.

Question 10

Electron configuration

Answer 10

The arrangement of an atom’s electrons within orbitals.

Question 11

Energy-level diagram

Answer 11

A schematic drawing used to arrange atomic orbitals in order of increasing energy levels.

Question 12

Inner-shell shielding

Answer 12

The tendency of inner-shell electrons to partially shield outer-shell electrons from the attractive pull exerted by the positively charged nucleus.

Question 13

Ionization energy

Answer 13

The amount of energy needed to pull an electron away from an atom.

Question 14

Isotope

Answer 14

Any member of a set of atoms of the same element whose nuclei contain the same number of protons but different numbers of neutrons.

Question 15

Mass number

Answer 15

The number of nucleons (protons plus neutrons) in the atomic nucleus. Used primarily to identify isotopes.

Question 16

Neutron

Answer 16

An electrically neutral subatomic particle found in the atomic nucleus.

Question 17

Noble gas shell

Answer 17

A graphic representation of a collection of orbitals of comparable energy in a multielectron atom. A noble gas shell can also be viewed as a region of space about the atomic nucleus within which electrons may reside.

Question 18

Nucleon

Answer 18

Any subatomic particle found in an atomic nucleus. Another name for either proton or neutron.

Question 19

Physical model

Answer 19

A representation of an object on some convenient scale.

Question 20

Probability cloud

Answer 20

A plot of the positions of an electron of a given energy over time as a series of tiny dots.

Question 21

Proton

Answer 21

A positively charged subatomic particle found in the atomic nucleus.

Question 22

Quantum

Answer 22

A small discrete packet of energy. Quantum number An integer that specifies the quantized energy level within an atom.

Question 23

Spectroscope

Answer 23

A device that uses a prism or diffraction grating to separate light into its color components and measure their frequencies.