Structure Of The Atom

Question 0

Law of constant composition

Answer 0

Any amount of a pure chemical substance always has the same percentage of elements by mass. Developed in 1799 by Joseph Proust.

Question 1

Law of conservation of matter

Answer 1

Developed in 1774 by Antoine Lavoisier. Matter can be neither created nor destroyed.

Question 2

Atomic theory

Answer 2

By John Dalton from 1803 to 1808.

1. Matter is made of indivisible atoms.
2. Each element has its own atom, and each atom of an element has the same properties
3. Chemical reactions are rearrangements of atoms in small whole number ratios

Question 3

Law of multiple proportions

Answer 3

John Dalton. When two elements can be combined to make two different compounds, and if samples of these two compounds are taken so that the masses of one of the elements are the same in both samples, then the ratio of the masses of the other element in these compounds will be a ratio of small whole numbers.

Question 4

Michael Faraday

Answer 4

Showed that electric current could cause chemical reactions to occur.

Question 5

Cathode ray tube

Answer 5

Developed by Sir William Crookes in 1870s. Thought cathode rays were negatively charges molecules, not electrons.

Question 6

J. J. Thomson

Answer 6

Determined cathode rays were electrons. Determined charge to mass ratio. e/m=-1.76e8 coulombs/gram

Question 7

Oil drop experiment

Answer 7

1909 by Robert Millikan. Allowed to find charge of electron

-1.60e-19 coulomb

Question 8

Plum pudding model

Answer 8

Electrons bathed in positive charge, like plum pudding with raisins. Came about from combo of oil drop and charge to mass ratio.

Question 9

Gold foil experiment

Answer 9

Ernest Rutherford. Shot heavy alpha particles at a gold foil. Few were deflected and bounced back.

Question 10

Nuclear model of the atom

Answer 10

Formulated through gold foil experiment, that atoms are mostly empty space with dense centers. Positive nucleus and negative electron space.