Atoms Quiz

Question 1

John Dalton 1766-1844

Answer 1

Dalton’s atom theory:
-ELEMENT = small, indivisible, dense, solid spheres
-atoms are NEITHER CREATED NOR DESTROYED
John Dalton, small indivisible falcon

Question 2

J.J Thomson 1856-1940

Answer 2

-cathode ray tube
-discovered ELECTRON
-atoms not invisible, SUBSTRUCTURE
-NO PROTONS yet, positive matter
-“plum pudding” / chocolate chip ice cream
Negative chips in positive ice cream

Question 3

Robert Millikan 1868-1953

Answer 3

-“Oil drop” apparatus
-determined exact charge, mass of electron
Robert Millikan spilt his oil can

Question 4

Ernest Rutherford 1871-1937

Answer 4

“Gold foil experiment”
•most particles passed straight through: atoms made of mostly EMPTY SPACE
•Since a few alpha particles deflected, atoms have a very SMALL, DENSE, POSITIVELY CHARGED CENTER (nucleus)
•Alpha particles = POSITIVE

Question 5

James Chadwick 1891-1974

Answer 5

• mass of atom larger than predicted

- discovered NEUTRON

Question 6

Niels Bohr 1885-1962

Answer 6

-atom configuration:
ELECTRONS are arranged in ENERGY LEVELS that ORBIT around the NUCLEUS
^negative atoms not drawn towards positive nucleus
-ground state, excited state, quantumized energy, wavelengths

Question 7

Democritus 450

Answer 7

• Greek
• all matter “stuff around us” is tiny invisible particles
• atomos

Question 8

Ground state

Answer 8

Electrons in lowest energy level

Question 9

Excited state

Answer 9

Electrons in energy levels higher than normal

Question 10

Electrically neutral

Answer 10

Total # of positive charges = total # of negative charges

Question 11

Atomic #

Answer 11

Total # of protons (and electrons if electrically neutral)

Located under element (subscript)

Question 12

Mass #

Answer 12

Protons + neutrons

Located above element

Question 13

Find the # neutrons

Answer 13

Mass # - atomic # = neutrons

Question 14

Isotopes

Answer 14

• Same atomic #, diff mass # (top #)

* same proton #, diff neutron #

Question 15

Atomic mass

Answer 15

Weighted average, naturally occurring isotopes of same element

Question 16

Find the Atomic Mass

Answer 16

%abundance •mass + %abundance •mass
/ 100

• nearest 100th
• check: should be in between lowest and highest mass

Question 17

If you round off the atomic mass of an element …,

Answer 17

You will obtain the mass number of the most abundant isotopes

Question 18

Isotopic notation

Answer 18

Element - mass #
Ex: Bi-209

Mass # : protons + neutrons

Question 19

Electron mass

Answer 19

0 (1/8836th amu)

Question 20

Electron mass

Answer 20

0 (1/8836th amu)

Question 21

History of atom models

Answer 21

• hard-sphere model
• electron shell model
• wave-mechanical model