Chapter 2 Atoms, Molecules, And Ions

Question 0

Law of Multiple Proportions

Answer 0

When two elements form a series of compounds, the ratios of the masses of the second element that combines with one gram of the first element can always be reduced to whole numbers.

Question 1

Law of Definite Proportion

Answer 1

A given compound always contains exactly the same proportion of elements by mass.

Question 2

Theory of Atoms

Answer 2

1. Each element is made up of tiny particles called atoms.
2. The atoms of a given element are identical; the atoms of different elements are different in some fundamental way.
3. Chemical compounds are formed when atoms of different elements combine with each other. A given compound always has the same relative numbers and types of atoms.
4. Chemical reactions involve reorganization of the atoms- changes in the way they a rebound together. The atoms themselves are not changed in a chemical reaction.

Question 3

Atomic Masses (Atomic Weights)

Answer 3

The weighted average mass of the atoms in a naturally occurring element.

Question 4

Avogadro’s Hypothesis

Answer 4

At the same temperature and pressure, equal volumes of different gases contain the same number of particles.

Question 5

Cathode-Ray Tubes

Answer 5

Electrical discharges in practically evacuated tubes.

Question 6

Electron

Answer 6

Negatively charged particles

Question 7

Charge to Mass Ratio

Answer 7

E/M=-1.76x10^8 C/g

E=electron charge
C=coulombs
M=mass

Question 8

Plum Pudding Model

Answer 8

Electrons (raisins) are dispersed in a positive charge cloud (pudding).

Question 9

Mass of an Electron

Answer 9

9.11x10^-31 kg

Question 10

Radioactivity

Answer 10

Spontaneous emission of radiation by uranium.

Question 11

Three Types of Radioactive Emission

Answer 11

1. γ - gamma rays, high energy “light.”
2. β - beta particles, high-speed electron.
3. α - alpha particles, 2+ charge.

Question 12

Nuclear Atom

Answer 12

Atom with a dense center of positive charge (nucleus) with electrons moving around the nucleus at a distance that is large relative to the nuclear radius.

Question 13

Proton

Answer 13

Positive charge equal in magnitude to the electron’s negative charge.

Question 14

Neutron

Answer 14

Has the same mass as proton, but has no charge.

Question 15

Mass and Charge of the Electron, Proton, and Neutron

Answer 15

• Electron -> 9.11x10^-31 kg -> 1-
• Proton -> 1.67x10^-27 kg -> 1+
• Neutron -> 1.67x10^-27 kg -> N/A

Question 16

Isotopes

Answer 16

Atoms with the same number of protons, but different numbers of neutrons.

Question 17

Atomic Number

Answer 17

Number of protons.

Question 18

Mass Number

Answer 18

Total number of protons and neutrons.

Question 19

Chemical Bond

Answer 19

The forces that hold atoms together in compounds.

Question 20

Covalent Bond

Answer 20

Atoms form bonds by sharing electrons.

Question 21

Molecule

Answer 21

A collection of atoms.

Question 22

Chemical Formula

Answer 22

The symbols for the elements are used to indicate the types of atoms present and subscripts are used to indicate the relative number of atoms.

Question 23

Structural Formula

Answer 23

Individual bonds are shown, indicated by lines.

Ex: H2O -> H-O-H

Question 24

Space-Filling Model

Answer 24

Shows the relative sizes of the atoms and orientation in the molecule.

Question 25

Ball-and-Stick Model

Answer 25

Also represents molecules

Ex: CH4     o
                   I
             o—O—o
                   I
                  o

Question 26

Ion

Answer 26

Atom(s) that has a net positive charge or negative charge.

Question 27

Cation

Answer 27

A positive ion.

Question 28

Anion

Answer 28

An ion with a negative charge.

Question 29

Ionic Bond

Answer 29

Force of attraction between oppositely charged ions.

Question 30

Ionic Solid (Salt)

Answer 30

Solid consisting of oppositely charge ions.

Question 31

Polyatomic Ion

Answer 31

Multiple atoms.

Question 32

Periodic Table

Answer 32

All the known elements.

Question 33

Metal

Answer 33

Tend to form positive ions.

Question 34

Nonmetal

Answer 34

Tend to form negative ions. They appear in the upper right-hand corner of the table (except hydrogen).

Question 35

Group (Family)

Answer 35

Elements in the same (vertical) column have similar chemical properties.

Question 36

Alkali Metal

Answer 36

Group 1A, highly active, 1+ charge with Nonmetals.

Question 37

Alkaline Earth Metal

Answer 37

Group 2A, 2+ charge.

Question 38

Halogens

Answer 38

Group 7A, diatomic, 1- charge.

Question 39

Noble Gases

Answer 39

Group 8A, monatomic gases.

Question 40

Period

Answer 40

Rows.