Atoms: The Building Blocks of Matter

Question 1

Dalton’s atomic theory

Answer 1

all matter is composed of extremely small particles called atoms

atoms of a given element are identical in size, mass, and other properties, but atoms of other elects differ in size, mass, and other properties

atoms cannot be subdivided, created, or destroyed

atoms of different elements combine in simple whole-number ratios to form chemical compounds

in chemical reactions, atoms are combined, separated, or rearranged

Question 2

false concept of Dalton’s atomic theory

Answer 2

atoms cannot be subdivided, created, or destroyed

Question 3

modern atomic theory

Answer 3

all matter is composed of atoms

atoms of any one element differ in properties from atoms of another element

Question 4

nucleus

Answer 4

a very small region near the center of an atom

contains protons and neutrons

extremely dense

positively charged

Question 5

law of conservation of mass

Answer 5

states that mass is neither created nor destroyed during ordinary chemical reactions or physical changes

Question 6

law of definite proportions

Answer 6

states that a chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or source of the compound

Question 7

law of multiple proportions

Answer 7

states that if two or more different compounds are composed of the same two elements, then the ratio of the masses of the second element combined with a certain mass of the first element is always a ratio of small whole numbers

Question 8

Ernest Rutherford

Answer 8

New Zealander physicist

discovered the nucleus

Question 9

John Dalton

Answer 9

English schoolteacher

formulated the basis for the Modern atomic theory

Question 10

mass of proton

Answer 10

1.673 × 10^-27kg

1amu

Question 11

mass of neutron

Answer 11

1.675 × 10^-27kg

1amu

Question 12

isotopes

Answer 12

atoms of the same element with different masses

contain the same number of protons and electrons

contain different number of neutrons

Question 13

atom

Answer 13

smallest particle of an element that retains the chemical properties of that element

Question 14

atomic mass unit

amu

Answer 14

exactly 1/12 the mass of a carbon-12 atom

Question 15

mole

mol

Answer 15

the amount of a substance that contains as many particles as there are in 12g of carbon-12 (6.02 × 1023)

amount of substance that contains Avagadro’s number of particles

Question 16

Avagadro’s constant

Answer 16

6.02 × 10²³

Question 17

average atomic mass

Answer 17

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

Question 18

molar mass

Answer 18

mass (in grams) of 1 mole of a pure substance

Question 19

formula mass

Answer 19

mass (in amu) of 1 particle of a substance

Question 20

Democritus

Answer 20

ancient Greek philosopher

called nature’s basic particle an “atom” (indivisible)

had no scientific proof that atoms existed (only speculation)

credited for providing the term “atom”

Question 21

Aristotle

Answer 21

ancient Greek philosopher

did not believe in atoms

believed that all matter was continuous

Question 22

mass of electron

Answer 22

9.109 × 10^-31kg

1/1837amu

Question 23

mass number

Answer 23

the total number of protons and neutrons in the nucleus of an isotope

Question 24

Amedeo Avagadro

Answer 24

Italian scientist

provided crucial explanations of the relationship between mass and numbers of atoms