Ch. 4 Atoms

Question 1

thought that you would eventually end up with a particle that could not be cut; the atom

Answer 1

Democritus

Question 2

found that all elements are made of atoms, atoms of the same element are exactly alike, and atoms join with other atoms to make new substances

Answer 2

Dalton

Question 3

discovered electrons and proposed the plum pudding model

Answer 3

Thomson

Question 4

did the gold-foil experiment and found that some particles deflect

Answer 4

Rutherford

Question 5

proposed that electrons move around the nucleus in certain paths

Answer 5

Bohr

Question 6

states that electrons don’t move in certain paths, but move in electron clouds

Answer 6

modern atomic theory

Question 7

the smallest unit of an element that maintains the properties of that element

Answer 7

atom

Question 8

a subatomic particle that has a negative charge

Answer 8

electron

Question 9

in physical science, an atom’s central region, which is made up of protons and neutrons

Answer 9

nucleus

Question 10

a region around the nucleus of an atom where electrons are likely to be found

Answer 10

electron cloud

Question 11

a subatomic particle that has a positive charge and that is found in the nucleus of an atom

Answer 11

proton

Question 12

a unit of mass that describes the mass of an atom or molecule

Answer 12

atomic mass unit

Question 13

a subatomic particle that has no charge and that is found in the nucleus of an atom

Answer 13

neutron

Question 14

the number of protons in the nucleus of an atom; the atomic number is the same for all atoms of the element

Answer 14

atomic number

Question 15

an atom that has the same number of protons but different number of neutrons

Answer 15

isotope

Question 16

the sum of the number of protons and neutrons in the nucleus of an atom

Answer 16

mass number

Question 17

the mass of an atom expressed in atomic mass units

Answer 17

atomic mass