Unit 1 Worksheet 1
Name:
Use the notes found on www.proflee.com, unit 1 materials to answer the following questions.
1. Who was the first scientist to name the negative particles in the nucleus as electrons?
G. D. Stoney named the atom’s negative particles electrons.
2. What are the five points of Dalton’s atomic theory?
John Dalton (Father of Atomic Theory) stated that
• all matter is composed of atoms
• all atoms of any one element have the same properties
• atoms cannot be created, destroyed, or subdivided
• when atoms of different elements combine they do so in whole number ratios and form a
chemical compound
• when elements undergo a chemical reaction, the atoms rearrange, combine or separate
3. Out of the 5 postulates, which one do we now know is not true?
Either
• all atoms of any one element have the same properties
or
• atoms cannot be created, destroyed, or subdivided
4. What was the basis for Mendeleev’s arrangement of elements on the periodic table?
Dmitri Ivanovich Mendeleev created a periodic table using atomic mass as a priority
arrangement.
5. What are the three conclusions that Rutherford concluded from his gold foil experiment?
Ernest Rutherford proposed that the atom is “mostly empty space with a tiny positive center made
of protons and negative electrons orbiting it.”
6. In what year were neutrons found and by whom?
1932
Sir James Chadwick discovered neutrons in the nucleus
7. Who discovered the charge of an electron? In what year?
1874
G. D. Stoney named the atom’s negative particles electrons.
8. Describe the Rutherford gold foil experiment.
Rutherford aimed positive alpha particles at a thin piece
of gold foil. The gold foil was surrounded by a screen
of ZnS (fluoresces in the presence of radiation). Most of
the radiation went straight through…but some was
deflected at large angles and even straight back.
9. Draw and label the lab setup for rutherford’s gold foil experiment.
10. How does the modern mo