Chemistry Honors - Unit 2 Scientists

J.J. Berzelius

Swedish chemist who created the modern symbols of elements

Who is credited with the word "atomos"?

Greek philosopher Democritus

What does atomos mean?

indivisible

What was the importance of alchemy?

They shifted from though to observation and experimentation. Developed true scientific methods, leading to important discoveries about matter, which helps establish important scientific principles for the Atomic Theory

Who re-proposed the Atomic Theory (after Democritus)?

John Dalton

What were the 3 important laws Dalton based his Atomic Theory?

Law of Conservation of Mass, Law of Constant Proportions, Law of Multiple Proportions

Law of Conservation of Mass

Mass is neither created nor destroyed, discovered by Antoine Lavoisier

Law of Constant Proportions

Compounds always contain the same elements in the same proportions by mass, discovered by Joseph Proust (Proust's Law)

Law of Multiple Proportions

When two elements can form multiple compounds, the ratio of masses will stay constant for each compound, discovered by John Dalton

What did Dalton's Atomic Theory propose?

1) Elements are made of small, indivisible particles called atoms

2) Each element is made up of atoms that are identical

3) Chemical reactions are simple rearrangements of atoms in small whole number ratios

What are the problems with the Atomic Theory?

1) Atoms are divisible into subatomic particles.

2) Atoms of an element aren't necessarily identical because of isotopes.

What did J.J. Thomson discover and determine?

He discovered subatomic particles and the electron using the Cathode Ray Tube. He determined the charge to mass ratio of the electron.

What did J.J. Thomson propose?

He proposed the Plum Pudding Model, which diagrams the atom.

What did Robert A. Millikan do?

He determined the charge of the electron with his oil drop experiment.

What did Henri Becquerel do?

He discovered radioactivity

What did Ernest B. Rutherford discover?

The atom's nucleus and protons using his golden foil experiment.

What did Rutherford prove?

The nucleus is positively charged and most of the atom is empty space.

What did Rutherford propose?

A planetary atomic model (electrons orbit the positive nucleus like planets around the sun) but it’s wrong

What did James Chadwick do?

He discovered the neutron

Who created the first artificial transmutation?

Rutherford

Who won the 1960 Nobel Prize in chemistry for development in 1947 of radiocarbon dating?

Willard Libby