Sections 2.3-2.4

Question 1

proposed the planetary model of the atom

Answer 1

Ernest Rutherford

Question 2

conducted the oil-drop experiment

Answer 2

Robert Milikan

Question 3

determined the mass of the neutron

Answer 3

James Chadwick

Question 4

In the gold-foil experiment, what unexpected observation led to replaying the “plumpudding” model?

Answer 4

the foil reflected some ions back

Question 5

Which subatomic particles have zero electrical charge?

Answer 5

neutron

Question 6

Which of the following subatomic particles is the lightest?

Answer 6

electron

Question 7

What are atoms of the same element that differ in their mass numbers?

Answer 7

isotopes

Question 8

What is the name for the number of protons in an atom?

Answer 8

atomic number

Question 9

Which number in an atomic symbol gives the number of protons?

Answer 9

the atomic number - the subscript or bottom number

Question 10

What does the superscript or top number of an atomic symbol tell us?

Answer 10

mass number

Question 11

How do you find the number of neutrons from an atomic sympbol?

Answer 11

Subtract the subscript or atomic number from the superscript or mass number

Question 12

How do you find the number of electrons?

Answer 12

If neutral, the same as the number of protons or atomic numbers; if positive, subtract the charge from the number of protons since it needs fewer electrons; if negative, add the charge to the number of protons since it needs more electrons