Chapter 3-Atoms

Question 1

chemical reaction

Answer 1

the transformation of a substance or substances into one or more new substances

Question 2

democritus

Answer 2

greek thinker, called natures’s basic particle an atom

Question 3

aristotle

Answer 3

did not believe in atoms and thought that all matter was continuous

Question 4

law of conservation of mass

Answer 4

mass is neither created nor destroyed, only rearranged

Question 5

law of definite proportions

Answer 5

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

Question 6

law of multiple proportions

Answer 6

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

Question 7

john dalton

Answer 7

reasoned that elements were composed of atoms and that only the whole numbers of atoms can combine to form compounds
created dalton’s atomic theory

Question 8

nucleus

Answer 8

very small region located at the center of an atom, made up of at least one positively charged particle called a proton and usually one or more neutral particles called neutrons

Question 9

proton

Answer 9

positively charged subatomic particle

Question 10

neutron

Answer 10

neutrally charged subatomic particle

Question 11

electron

Answer 11

negatively charged subatomic particle

Question 12

what are the two regions of an atom?

Answer 12

nucleus and electron cloud

Question 13

who discovered the electron and what did he use?

Answer 13

JJ Thomson, Cathode Ray Tube

Question 14

who measured the charge of the electron?

Answer 14

Robert A. Millikan

Question 15

who proposed the plum pudding model?

Answer 15

JJ Thomson

Question 16

who discovered the nucleus and how?

Answer 16

Ernest Rutherford, gold foil experiment

Question 17

who proposed specific electron placement?

Answer 17

Niels Bohr

Question 18

nuclear forces

Answer 18

short range proton-neutron, proton-proton, and neutron-neutron forces that hold the nuclear particles together

Question 19

how much is one mole?

Answer 19

6.02x10^23

Question 20

atomic number

Answer 20

number of protons of each atom of that element

Question 21

isotopes

Answer 21

atoms of the same element that have different masses (different numbers of neutrons)

Question 22

mass umber

Answer 22

total number of protons and neutrons that make up the nucleus of an isotope

Question 23

nuclide

Answer 23

general term for a specific isotope of an element

Question 24

atomic mass unit

Answer 24

amu

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

Question 25

average atomic mass

Answer 25

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

Question 26

molar mass

Answer 26

the mass of one mole of a pure substance

Question 27

ion

Answer 27

and atom with an uneven number of protons and electrons

Question 28

cation

Answer 28

a positive ion

Question 29

anion

Answer 29

a negative ion

Question 30

radioactivity

Answer 30

when the nucleus of an atom is unstable

Question 31

fusion

Answer 31

two nuclei are joined to make a larger nucleus

Question 32

nuclear transmutation

Answer 32

turning elements into different elements by changing number of protons

Question 33

fission

Answer 33

splitting of a nucleus

Question 34

alpha decay

Answer 34

emission of an alpha particle (equivalent to a helium nucleus) by the nucleus
atomic number decreases by 2, mass number decreases by 4

Question 35

beta decay

Answer 35

an electron emitted from the nucleus=beta particle
neutron splits into one proton and one electron, emitting the beta particle
atom’s atomic number increases by 1

Question 36

half life

Answer 36

how long it takes for a sample of radioactive material to decay into its daughter isotope

Question 37

how do you calculate average atomic masss?

Answer 37

average atomic mass= (mass of isotope 1 x fractional abundance of isotope 1) + (mass isotope 2 x fractional abundance of isotope 2)
enter percentage as decimals so you do not have to divide by 100 at the end