Physical science Test 11/20/ 25 STM 801 4th period

Democritus

1. matter is formed of small pieces that cannot be broken down.  Used the word Atomos (def.= uncuttable)

2. Did not prove existence of atoms - no experiments were performed

3. 430 B.C.

Idea of atoms began to develop 

1. 1660’s

2. people did experiments so ideas did not just remain ideas

Atomic Theory began to take shape

1. Atomic theory grew as a series of models that developed from experimental evidence.  

2. As more evidence was collected, the theory and models were revised.

Where was Dalton from

England

Main ideas of Dalton Theory

1. Elements consist of small particles called atoms

2. Atoms cannot be created or destroyed in a chemical reaction

3. Atoms of the same element are identical

4. Atoms of different elements have different masses and properties

5. Chemical reactions are rearrangement of atoms

6. Compounds are formed by a combination of two or more different atoms 

1803

Thomson Mode

1. JJ Thomson - British scientist

2. Suggested that atoms had negatively charged electrons embedded in a positive sphere

1897

Rutherford Gold Foil Experiment

1. Thomson student

2. Inferred that an atom’s positive charge must be clustered in a tiny region in its center, called the nucleus.

3. An atom was mostly empty space

4. Named the particles - protons

1911

Bohr’s Model

1. Niels Bohr suggested that electrons move in specific orbits around the nucleus of an atom

1913

Erwin Schrödinger

1. develops the quantum mechanical model, which describes electrons as existing in probability "clouds" or orbitals around the nucleus, with their exact location being uncertain. 

1926

James Chadwick

1. discovers the neutron, a neutral particle found in the nucleus with a mass similar to a proton. 

1932

Characteristics of metals 

Shiny, Malleable, Ductible, good conductors of heat and energy, most solid at room temperature, High melting and boiling points, and they typically lose electrons when bonding forming positive ions  

characteristics of nonmetals

Bad conductors of heat and energy, Brittle when solid, not shiny, Typically gain electrons when forming chemical bonds, wide range of chemical reactiveness, and they can be solid liquid or gas at room temperature.

characteristics of metalloids

Share properties of metals and non metals, Shiny, brittle when solid, can conduct electricity under certain conditions, typically solid at room tempature

alkali metals

Very reactive metals. All have 1 valence electron.

Alkaline Earth Metals

Reactive metals that form +2 ions.

Actinides

Mostly man made and radioactive with very short half-lives.

Lanthanides

Rare earth elements. Metals with very high luster.

Noble Gases

Elements with full valence shells. Do not form compounds easily. Very unreactive.

Halogens

These elements have 7 valence electrons. Form -1 ions and combine easily with Alkali Metals

Democritus date

430 B.C.

Dalton’s theory date

1803

Thomson Model date

1897

Rutherford Gold Foil Experiment date

1911

Bohr’s model  date

1913

 Erwin Schrödinger date

1926

James Chadwick

1932