Atom Scientist

They also knew that the electron had little orno mass, therefore he reasoned that all of an atom's mass is in positively charged nucleus. He called these positively charged particles in the nucleus, protons.

(Earnest Rutherford)

1897 worked with cathode ray tube and passed electricity inside empty glass tubes. He used magnets to pull the rays apart.

(JJ Thomson)

This mysterious glow "cathode rays" in the tube, he theorized were made of electrons.

(JJ Thomson)

All elements are composed of atoms that cannot be divided

(John Dalton)

Theorized that electrons must have only a specific amount of energy. This is similar to the way planets move around the sun.

(Neils Bohr)

Atoms of the same element are exactly the same and have the same mass.

(john dalton)

Bohr

1) Todays Planetary Model. (Protons and neutrons in the nuclus, electrons revolving around)

What discoveries are each of the people famous for?

Democritus: naming the atom as identical indivisable units. Aristotle: didn't believe you could ever stop dividing. Dalton: performed experiments to prove atom existed. Thompson: discovered smaller particles inside atom (electrons). Rutherford: revised model to include nucleus. Bohr: electrons orbit nucleus. Schrodinger: electrons orbit in clouds. Chadwick: discovered neutrons.

Chadwick

Discovered the neutron.

Thomson

Discovers the electron. Made the Plum Pudding Model.

What discovery demonstrated that atoms are not the smallest particles?

J.J. Thomson discovery of electrons inside atoms.

In his model the electrons are scattered throughout a ball of positive charge.

JJ Thomson

PLUM PUDDING OR RAISIN MUFFIN MODEL

JJ Thomson

Worked with Earnest Rutherford. Credited with discovering the neutron. His discovery completed the atomic model.

James Chadwick

PLANETARY MODEL

Neils Bohr

What are the two differences between the atomic theory described by Thomson and that described by Rutherford.

Thomson's theory included the atoms having electrons, while Rutherford's said that atoms have a nucleus and electrons orbit the nucleus. the two differences are where the electrons ARE and nucleus or no-nucleus.

Rutherford

a) Gold Foil Experiment. b) Discovered the nucleus c) Atom mainly empty space.

Dalton

a. matter = tiny spheres called atoms b. matter = only one type of atom

Even though it is the same ________________ as a proton it is electricity neutral, hence the name neutron.

mass

In what part of the atom is most of the mass located?

nucleus

All atoms of a single element have the same ___________ of ______________.

number; protons

What does the current model of the atom look like?

the current model of an atom has a nucleus in the center, and many electron clouds orbiting around it.

Identify the difference in how Bohr's theory and the modern theory describe the location of electrons.

the difference is that Bohr's theory was that electrons orbited in definite circular paths, while the modern theory says that electrons orbit in clouds.