Chapter 1. Chemical Foundations

Question 1

Scientific Method

Answer 1

The process of studying natural phenomena, involving observations, forming laws and theories, and testing of theories by experiment.

Question 2

Hypothesis

Answer 2

One or more assumptions put forth to explain the observed behavior of nature.

Question 3

Theory

Answer 3

A set of assumptions put forth to explain some aspect of the observed behavior of the matter.

Question 4

Model

Answer 4

A set of assumptions put forth to explain the observed behavior of matter. The models of chemistry usually involves assumptions about the behavior of individual atoms or molecules.

Question 5

Natural Law

Answer 5

A statement that expresses generally observed behavior.

Question 6

Law of Conservation of Mass

Answer 6

mass is neither created nor destroyed.

Question 7

Law of definite porportions

Answer 7

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

Question 8

Atomic Weights

Answer 8

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

Question 9

Avogadro’s hypothesis

Answer 9

One or more assumptions put forth to explain the observed behavior of nature.

Question 10

Cathode-ray tubes

Answer 10

the ‘‘rays’’ emanating from the negative electrode (cathode) in a partially evacuated tube: a stream of electrons

Question 11

Electrons

Answer 11

A negatively charged particle that moves around the nucleus of the atom

Question 12

Radioactivity

Answer 12

The spontaneous decomposition of a nucleus to form a different nucleus

Question 13

Nuclear atom

Answer 13

an atom having a dense center of positive charge(the nucleus) with electrons moving around the outside.

Question 14

Nucleus

Answer 14

the small, dense center of positive charge in an atom.

Question 15

protons

Answer 15

a positively charged particle in an atomic nucleus.

Question 16

Neutrons

Answer 16

a particle in the atomic nucleus with mass virtually equal to the protons but with no charge.

Question 17

Isotopes

Answer 17

atoms of the same element ( the same number of protons) with different numbers of neutrons. they have identical atomic numbers but different mass numbers

Question 18

Atomic number

Answer 18

the number of protons in the nucleus of an atom.

Question 19

mass number

Answer 19

the total number of protons and neutrons in the atomic nucleus of an atom

Question 20

Ion

Answer 20

an atom or a group of atoms that has a net positive or negative charge

Question 21

Cation

Answer 21

A positive ion.

Question 22

Anion

Answer 22

A negative ion.

Question 23

Dalton’s Atomic Theory

Answer 23

All elements are composed of atoms.
all atoms of a given element are identical
chemical compounds are formed when atoms combine
atoms are not changed in a chemical reaction but the way they are bounded together change.

Question 24

Thomson Model

Question 25

Milikan experiment

Question 26

Rutherford experiment

Question 27

nuclear model

Answer 27

Proposed by Rutherford in in 1911 pictures the atom as a heavy, positively charged nucleus, around which much lighter, negatively charged electrons circulate.