Honors CHEM - Atoms (electrons, protons, neutrons) and History of the Atom

+1

Charge of protons

-1

Charge of electrons

0

Charge of neutrons

1

Relative mass of protons

1

Relative mass of neutrons

1/1840

Relative mass of electrons

nucleus

location of protons

nucleus

location of neutrons

surrounding the nucleus

location of electrons

He believed matter was made up of tiny particles

What did Democritus believe about matter?

atoms

What word do we get from Democritus's description?

law of constant composition and law of conservation of mass

What are two laws of chemical combination?

a) elements are made up of atoms b) atoms of the same element are identical and atoms of different elements are not identical c) atoms of different elements can combine to form compounds d) atoms are indivisible in chemical processes

What were John Dalton's basic ideas about matter?

a solid sphere

What is Dalton's model of an atom?

JJ Thomson

What British physicist was studying the inside of the atom?

Cathode rays

What was Thomson's experiment?

The rays had a negative charge because they contain electrons

What did Thomson learn from the cathode rays?

It proved the existence of subatomic particles, disproving the idea that atoms are solid spheres

How did this discovery disprove Dalton's idea of an atom?

Electrons

What are the cathode rays made up of?

Opposite charged magnet

What causes the bending of the cathode ray?

Plum pudding

What was Thomson's model of the atom

Gold foil

What was Ernest Rutherford's experiment

the center was a positive nucleus

When the alpha particle bounced off the gold nucleus, what conclusion can be made about the atom?

it proves the existence of subatomic particles and that the atom is not a solid sphere

How does Rutherford's discovery disprove Dalton's idea about the atom?

quantam mechanics

the correct theory of the atom

Bohr

who proposed quantam mechanics (orbitals)

Neutrons

What did Chadwick discover about the atom?

they affect the mass of an atom

How do neutrons affect an atom of an element?

Law of constant composition

a chemical compound always contains the same elements in the same proportions by mass, regardless of the source or method of preparation

law of conservation of mass

matter cannot be created nor destroyed