1. William Crookes & John Dalton

2. William Crookes Who was he?
He was born in the 17th day of June 1852, and died the 4th day of April He was a chemist and physicist He attended to the royal college of chemistry in London and worked on spectroscopy.

3. William Crookes What did he discover ?
In 1861 William Crookes discovered a new uncnown element with a bright green emission line in its spectrum, and named the element thallium

4. William Crookes His conclusion:
Conclusion: Cathode r0ays are negatively charged by studying deflection of cathode rays by magnetic fields.

5. John Dalton Who was he ?
He was born on the 6th of Septemer 1766 and died 27th of July He was and English chemist, meteorologist and physicist. He was know best for his pioneering work in the development of modern atomic theory, and his research into colour blindness.

6. Jonh Dalton What did he do ?
He was the first person to puplish the table of relative atomic weights in October He created the atom theory: Elements are made of tiny particles called atoms. All atoms of a given element are identical

7. Table of relative atomic weights