history of the atom

give me the names of those who assisted in the history of the atom iN ORDER

John Dalton, JJ Thomson, Ernest Rutherford and his student Ernest Marsden, Niels Bohr,Ernest Rutherford, James Chadwick

Who was the first person to explore atoms at the start of the 19th century?

John dalton

What did John Dalton do?

John Dalton described atoms as indivisible solid spheres, with different types of spheres making up different elements

How did JJ Thomas make the plum pudding model?

By using a cathode ray tube, JJ Thomson was able to discover electrons. This was because the ray was attracted to the positive magnet. This disproved John Dalton’s theory and showed that atoms could be split. Using this, he made the plum pudding model

What did JJ Thomas do?

concluded from his experiments that atoms were not solid spheres. His measurements of charge and mass showed that an atom must contain even smaller negatively charged particles- electrons. The new theory was known as the plum pudding model

what did the plum pudding model show

atoms as a ball of positive charges with electrons stuck in it

what was the first major theory that tried to explain what ‘stuff was made out from?

Atomic theory

what did Ernest Rutherford and his students do?

they took positively charged alpha particles and fired them at a thin sheet of gold. If the positive charge was spread out, then the alpha particles should spread through

what did Ernest Rutherford create?

The nuclear model

What did Ernest Rutherford discover? (first discovery)

that there was some sort of compound nucleus which contained the positive charges. He thought the negative charge existed in a cloud around the nucleus

What did Niels Bohr suggest?

that the electrons orbited the nucleus

what did further experiments by Ernest Rutherford find?

that the nucleus is made up of protons

who said atoms were tiny, hard, indestructible spheres?

John Dalton

What did James Chadwick discover?

neutrons

What happened instead of the alpha particles spreading through?

a small number were deflected and others moved at other directions

What charge are alpha particles?

positive

What did Ernest Rutherford and his student do?

they conducted the famous alpha particle scattering experiment, where the alpha particles were expected to just pass through the thin sheet of gold . However, a few were deflected. Rutherford came to the conclusion that there was a tiny positive nucleus at the centre, where most of the mass is concentrated, and a cloud of electrons around it Most of the atom is empty space.

what was the flaw in the nuclear model?

If the electrons were ‘a cloud around the nucleus’, then they would be attracted to the nucleus, causing the atom to collapse

What did Bohr state in regard to the nuclear model flaw?

Bohr suggested that the electrons orbited the nucleus in shells, as the planets do around the sun. This was supported by many experiments.

What did further experiments by Rutherford show (after shells were theorised))

that the nucleus could be divided into smaller particles- protons

Who discovered the last element of atoms

James Chadwick

How did James Chadwick discover neutrons?

by carrying out an experiment which provided evidence for neutral particles

What did James Chadwick discover?

neutrons

What was the setup for Ernest Rutherford’s discovery of the nuclear model

They shot alpha particles at a thin sheet of plastic. It was expected that these alpha particles would just go through

What was the experiment that JJ Thomson did to get the plum pudding model?

using a beam of particles and magnets

What was atomic theory about?

the idea that everything is made up from indivisible particles

What did Rutherford conclude (1st)

that there was a tiny positive nucleus at the centre, where most of the mass is concentrated, and a cloud of electrons around it. Most of the atom is empty space