In 1909, Robert Millikan performed an experiment involving tiny, charged drops of oil. The drops were charged because they had picked up extra electrons. Millikan was able to measure the charge on each drop in coulombs. Here is an example of what his data may have looked like.
Based on the given data, how many extra electrons did drop C contain?
A 3.20times 10^{-19}
B 4.80times 10^{-19}
C 8.00times 10^{-19}
D 9.60times 10^{-19}
answer
5 electrons
question
Why did different drops have different charges?
answer
Because some drops had picked up more electrons than others.
question
What did each of the following scientists contribute to our knowledge of the atom?
James Chadwick
Michael Faraday
Eugen Goldstein
J.J Thomson
William Crookes
Ernest Rutherford
answer
Chadwick- discovered the neutron.
Faraday- developed electrolysis.
Goldstein- discovered the proton.
Thomson- discovered the electron.
Crookes- developed the cathode ray tube.
Rutherford- proposed the nuclear theory of the atom.
question
What is radioactivity?
answer
Radioactivity is spontaneous radiation from an atomic nucleus.
question
How did the discovery of radioactivity contradict Dalton's atomic theory?
answer
Dalton's Atomic theory stated that atoms were indestructible.
question
Unstable atomic nuclei decay to form nuclei that are usually more stable. In the process, they emit high-energy particles. These particles, called nuclear radiation, occur in three different forms:
alpha (α) particles,
beta (β) particles, and
gamma (γ) rays.
Alpha particles are helium nuclei, with two neutrons and two protons. Beta particles are high-energy electrons. Gamma rays are high-energy photons, a form of electromagnetic radiation just like visible light but of much higher energy.
Match each description to a type of radiation.
answer
charge =+2 A particle
charge = -1 B particle
least penetration A particle
mass =0 amu Y ray
medium penetration B particle
deepest penetration Y ray
mass~1/2000 amu B particle
mass~4 amu A particle
charge = 0 Y ray
question
Rank the following by speed.
1.alpha (α ) particles,
2.beta (β ) particles, and
3.gamma (γ ) rays.
answer
Fastest
gamma
beta
alpha
slowest
question
Which is the charge of an alpha particle?
answer
+2
question
Conclusions from Rutherford's experiment
Watch the animation depicting Rutherford's experiment and choose which of the following conclusions are correct.
1. A positive charge is condensed in one location within the atom.
2. A positive charge is spread equally over the atom.
3. The atom is a very compact entity without any empty space.
4. The atom does not have a positive charge.
5. The majority of the space inside the atom is empty space.
answer
1. A positive charge is condensed in one location within the atom.
5. The majority of the space inside the atom is empty space.
question
The structure of the atom
On the basis of Rutherford's experimental observations, which of the following statements predicts the structure of the atom?
1. In an atom, negatively charged electrons are small particles held within a positively charged sphere.
2. In an atom, negatively charged electrons are dispersed in the space surrounding the positively charged nucleus of an atom.
3. In an atom, all of the positive and negative charges are randomly distributed.
4. In an atom, most of the mass and the positive charge are located in a small core within the atom called the nucleus.
answer
2. In an atom, negatively charged electrons are dispersed in the space surrounding the positively charged nucleus of an atom.
4. In an atom, most of the mass and the positive charge are located in a small core within the atom called the nucleus.
question
Sort each of the items into the appropriate bin. Use the diagram of a neutral lithium atom, shown to the left, for reference.(Figure 1)
Drag each item to the appropriate bin.
answer
Proton:
Particle labeled "B"
+1 charge
approximately the same mass as a neutron
Neutron:
Particle labeled "A"
no charge
Electron:
Particle labeled "C"
-1 charge
smallest mass of the three particles
question
In Rutherford's model of the atom, where are the protons, the neutrons, and the electrons found?
answer
in the nucleus:
protons, nutrons
surrounding the nucleus:
electrons
question
The following table describes four atoms.
Atom A Atom B Atom C Atom D
Number of protons 20 21 21 20
Number of neutrons 21 20 21 20
Number of electrons 20 21 21 20
answer
Are atoms A and B isotopes? No
Are atoms A and C isotopes? No
Are atoms A and D isotopes? Yes
Are atoms B and C isotopes? Yes
Are atoms C and D isotopes? No
question
Which two atoms in the table have about the same mass?
Atom A Atom B Atom C Atom D
Number of protons 17 18 18 17
Number of neutrons 18 17 18 17
Number of electrons 17 18 18 17
answer
4. A and B
*the atomic number is the number of protons in an element, while the mass number is the number of protons plus the number of neutrons.
question
How many different isotopes of silver are listed here? (The X does not necessarily represent any specific element.)
108/47 X 108/48 X 110/47 X 107/47 X
answer
3 isotopes
* in the example you can see that element with atomic number 47, but different mass numbers 108,109,107 are isotopes.
question
How many protons and neutrons are there in a
34 S
16
nucleus?
1. 34 neutrons and 16 protons
2. 18 protons and 16 neutrons
3. 18 neutrons and 16 protons
4. 50 neutrons and 16 protons
answer
3. 18 neutrons and 16 protons
*34 is the mass
16 is the atomic number/ protons
subtract 34-16=18
question
What theory uses wave properties to describe the motion of particles at the atomic and subatomic levels?
1. the Dalton model
2. the quantum mechanical model
3. the Bohr model
4. the electrolysis mode
answer
2. the quantum mechanical model
Haven't found what you need?
Search for quizzes and test answers now
Quizzes.studymoose.com uses cookies. By continuing you agree to our cookie policy