Atomic Theory / Periodic Table Study Guide

How many elements are on the Periodic Table?

118

How many elements occur naturally?

90

When did the Big Bang Theory occur?

14 billion years ago

How did the Big Bang Theory occur?

Began from a single point that was extremely hot and dense. It was expanding rapidly, so the flash from the Big Bang caused the formation of matter, which created protons, neutrons, and electrons.

What are the three subatomic particles?

Protons, Neutrons, and Electrons

What is matter?

• Anything that has mass and takes up space

What is the smallest particle of matter that retains its properties?

An atom

Who discovered the electron?

J. J. Thomson

Who discovered the proton?

Eugen Goldstein

Who discovered the neutron?

James Chadwick

What did Democritus believe?

Matter was composed of individual particles

Democritus…

Democritus

• Think about the existence of atoms

• Thought matter was composed of individual particles

• No model

What did John Dalton specifically do?

Used experiments to transform Democritus’ ideas on atoms. Used ratios

John Dalton..

• John Dalton

• Studied ratios in which elements combine in chemical reactions

• Used experiments to transforms Democritus’ ideas

What is Dalton’s Atomic Theory?

1. All elements are composed of tiny indivisible particles called atoms

2. Atoms of the same element are identical. Atoms of different elements are different from those of different elements.

3. Atoms of different elements can physically mix together or chemically combine in simple whole number ratios.

4. Chemical reactions occur when atoms are separated, join together, or rearrange in different combinations, Atoms of 1 element are never changed into atoms of another element as a result of a chemical reaction

What are the 3 subatomic particles?

Protons, Neutrons, and Electrons

What was the Cathode Ray Expierment?

In a tube there was an electric gas and 2 plates, postive and negative. The particles in the gas were attracted to the positive plate, meaning that the particles MUST have a negative charge. 

What did JJ Thomson discover with the Cathode Ray Expierment?

Electrons

When subatomic particles were discovered, what did scientists wonder?

How the atom was put together 

What did J.J. Thomson think about the distribution of electrons in the atom?

He thought electrons were evenly distributed throughout the atom

What Thomson’s model of the atom called?

• Plum Pudding, where electrons were struck into lumps of positive charge