Atoms

Question 1

Ernest Rutherford

Answer 1

Positively charged, dense nucleus and later came up with protons
Atoms are mainly empty space
Gold foil experiment

Question 2

Democritus

Answer 2

All matter is made of atoms

Question 3

John Dalton

Answer 3

Atoms are small, indestructible masses (incorrect)
Atoms of an element are identical
3 ideas of atomic theory

Question 4

J.J. Thomson

Answer 4

Used a Cathode Ray tube
Atoms contain negatively charged particles called electrons
Electrons are lighter than Helium, the lightest element
Plum Pudding Model

Question 5

Robert Millikan

Answer 5

Oil drop experiment
Found the charge of an electron and mass of an electron (~1/1840 of a helium atom)

Question 6

Niels Bohr

Answer 6

Electrons exist on specific energy levels
Electrons can absorb and release energy and move between energy levels

Question 7

James Chadwick

Answer 7

Proved existence of neutrons

Answer 8

Quantum Theory
Electrons behave like waves
Electrons do not orbit but exist in regions of space called clouds
Cannot determine exact electron position
Protons have a relative mass of 1
Neutrons have a relative mass of 1 (slightly heavier than protons)

Question 9

Law of Definite Proportions

Answer 9

Compounds will always contain the same proportions by mass, regardless of sample size

Question 10

Law of Conservation of Mass

Answer 10

In a chemical reaction, mass is neither created nor destroyed

Question 11

Law of Multiple Proportions

Answer 11

The ratio of one element combining with another to form a compound is always expressed in small whole numbers

Question 12

Atomic Number

Answer 12

Number of protons
What identifies an element and is unique for each element

Question 13

Mass Number

Answer 13

Number of protons and neutrons
Used to find the number of neutrons

Question 14

Charge

Answer 14

Number of electrons

Question 15

Isotopes

Answer 15

Same element but a different number of neutrons (therefore a different mass)