Chapter 2- Atoms, Molecules, and Ions

Question 1

Democritus (400 BC)

Answer 1

used the term atomos to describe the small, indivisible, particles

Question 2

Dalton (1808)

Answer 2

• law of multiple proportions
• each element is made up of tiny particles called atoms that are identical
• a given compound always has the same relative numbers and types of atoms
• chemical reactions involve arrangements of the atoms

Question 3

Thompson (1897)

Answer 3

• cathode ray experiment
• discovered the electrons
• discovered that cathode rays are made of electrons that are found in all atoms
• plum pudding model

Question 4

Rutherford (1911)

Answer 4

• gold foil experiment
• named a, b, y particles
• most of the atom is empty space with a dense positively charged nucleus (1919)

Question 5

Chadwick (1932)

Answer 5

discovered neutron

Question 6

Lavoisier

Answer 6

law of conservation of mass

Question 7

Proust

Answer 7

law of definite proportion

Question 8

mass number

Answer 8

• the total number of protons and neutrons

- round atomic weight to nearest whole number

Question 9

atomic number

Answer 9

• number of protons

- number of electrons = number of protons

Question 10

atomic mass (weight)

Answer 10

the weighted average of the masses of the naturally occurring isotopes of an element

Question 11

isotopes

Answer 11

atoms with the same number of protons but different number of neutrons

Question 12

molecule

Answer 12

an electrically neutral group of at least two atoms in a definite arrangement held together by covalent bonds

Question 13

covalent bond

Answer 13

sharing electrons

Question 14

ionic bonds

Answer 14

transferring electrons

Question 15

ion

Answer 15

an atom or molecule in which the total number of electrons is not equal to the total number of protons, giving it a net negative or positive charge

Question 16

ionic compound

Answer 16

• forms crystals
• has high melting and boiling points
• conducts electricity when it dissolves in water

Question 17

polyatomic ion

Answer 17

• a charged species composed of two or more atoms

- compounds with polyatomic ions are ionic

Question 18

group

Answer 18

a vertical column of elements with same valence electron configuration ad similar properties

Question 19

period

Answer 19

a horizontal row of elements

Question 20

group 1

Answer 20

alkali metals

Question 21

group 2

Answer 21

alkaline earth metals

Question 22

group 17

Answer 22

halogen

Question 23

group 18

Answer 23

noble/ inert gases

Question 24

representative elements

Answer 24

group 1, 2, and 13 to 18

Question 25

transition elements

Answer 25

groups 3 to 12

Question 26

oxyanions

Answer 26

• contain an atom of a given element and different number of oxygen atoms
• smaller number of oxygen atoms ends in “-ite”
• larger number of oxygen atoms ends in “-ate”

Question 27

hypo-

Answer 27

prefix for oxyanion members of a series with the fewest oxygen atoms

Question 28

per-

Answer 28

prefix for oxyanions members of a series with the most oxygen atoms