Question 1

Which scientist described a positively charged core ('nucleus") in the middle of a lot of empty space?

Accepted Answer

Rutherford

Answer

Thomson

Answer

Chadwick

Answer

Bohr

Question 2

A scientist uses a radiation source to bombard a sample atom with positively charged ions. Observations show that MOST of the positive ions pass through the atom while SOME of the positive ions are deflected. Why is model B a more accurate representation of the atom than model A?

Accepted Answer

Model B shows an atom that is mostly empty space and has a positive center.

Answer

Model B shows an atom filled with positive and negative charges which repel most of the positive ions.

Answer

Model B shows an atom with a negative center that allows most of the positive ions through.

Answer

Model B shows an atom with a negative center which repels most of the positive ions.

Question 3

Look at the chart, which two atoms are isotopes of one another?

Accepted Answer

Atoms 1 & 4

Answer

Atoms 1 & 2

Answer

Atoms 1 & 3

Answer

Atoms 2 & 3

Question 4

Look at the chart, which two atoms have the same mass?

Accepted Answer

Atoms 2 & 4

Answer

Atoms 1 & 4

Answer

Atoms 2 & 3

Answer

Atoms 1 & 2

Question 5

According to the modern concept of the atom, which subatomic particles are located in the nucleus of an atom?

Accepted Answer

neutrons and protons

Answer

protons only

Answer

protons and electrons

Answer

neutrons and electrons

Question 6

Which subatomic particle(s) have a mass of 1 amu?

Accepted Answer

proton and neutron

Answer

proton

Answer

proton and electron

Answer

electron

Question 7

An element has two isotopes. One isotope has a relative abundance of 75.0% and mass 25.0 amu. The second isotope has a relative abundance of 25.0% and 28.0 amu. What do you predict is the average atomic mass of the element?

Accepted Answer

25.8

Answer

27.3

Answer

26.5

Answer

258

Question 8

The element gallium (Ga) has two naturally occurring isotopes Ga-69 and Ga-71. The average atomic mass of gallium listed on the periodic table is 69.723 amu. Which naturally occurring isotope Ga-69 or Ga-71 is most abundant?

Accepted Answer

Ga-69 because the average atomic mass of the element is closer to its mass

Answer

Ga-71 because it has more neutrons resulting in more distance between the protons

Answer

Ga-71 because it has a greater mass

Answer

Ga-69 because it has fewer neutrons

Question 9

What is the correct isotope notation for an atom that has 23 protons and 29 neutrons?

Accepted Answer

Vanadium-52

Answer

Copper-52

Answer

Vanadium-29

Answer

Carbon-29

Question 10

If an atom has 35 AMU mass number and 18 neutrons, what is the identity of the atom?

Accepted Answer

Cl

Answer

Cu

Answer

Na

Answer

P

Question 11

A student is researching atomic bombs and uranium isotopes appear several times in the article. The student does not understand isotopes. Which explanation below would best fit your claim to clarify the students understanding?

Accepted Answer

Isotopes of uranium are the same element because they have the same number of protons which makes them the same element.

Answer

Isotopes of uranium are the same element because they are unique in that they do not follow the definition of an isotope.

Answer

Isotopes of uranium are not the same element but are in the same family as the main element uranium.

Answer

Isotopes of uranium are not the same element because but have the same number of electrons, therefore electrons do not change in isotopes even when forming positive and negative ions.

Question 12

Students are given the following data for determining the average atomic mass of lithium. A sample of lithium consists of 400 atoms. 30 atoms are the isotope Lithium-6 (6.015 amu) and 370 are Lithium-7 (7.016 amu).  Which student correctly calculated the correct average atomic mass and why?

Accepted Answer

Student 1 calculated the average atomic mass as 6.94 amu.  Student 1 determined the percent abundance for each isotope and then multiplied the percent abundance by the average atomic mass of its isotope and took the sum.

Answer

Student 4 calculated the average mass as 13.0 amu.  Student 4 added the mass of the two isotopes.

Answer

Student 3 calculated the average atomic mass as 1.06 amu.  Student 3 took the sum of the average atomic masses of the isotopes and multiplied by  the ratio of lithium-6 to lithium-7.

Answer

Student 2 calculated the average atomic mass as 6.52 amu.  Student 2 took the average of the mass of the two isotopes of lithium.

Question 13

A scientist is monitoring the levels of strontium-90 in her company’s dairy products. What observation will allow her to conclude that the level of strontium-90 is above the naturally-occurring level? The average atomic mass of naturally-occurring strontium-90 is 87.62 amu.

Accepted Answer

The average atomic mass of the strontium atoms in the sample is above 87.62 amu.

Answer

The average atomic mass of the strontium atoms in the sample is 87.62 amu.

Answer

The average atomic mass of the strontium atoms in the sample is below 87.62 amu.

Answer

More data on the relative abundance of each strontium isotope is required.

Question 14

A sample of phosphorus was isolated and analyzed to determine the percent abundance of each isotope. The results are recorded in the table. Based on the data, which statement gives the best reasoning for the average atomic mass for the isotopes is 31.14 amu?

Accepted Answer

It is the weighted average mass of all the different isotopes found in a sample of phosphorus

Answer

It is an integer number

Answer

It is the total number of neutrons and electrons in the isotopes found in a sample of phosphorus

Answer

It is the total number of neutrons, protons, and electrons in the isotopes found in a sample of phosphorus

Question 15

Which of the following has a negative charge?

Accepted Answer

Electron

Answer

Nucleus

Answer

Proton

Answer

Neutron

Question 16

The most convincing evidence for the existence of electrons came from which of the following experiments

Accepted Answer

cathode ray tube

Answer

canal rays

Answer

bombarding beryllium with high-energy A-particles

Answer

the gold foil experiment

Question 17

According to the figure to the right, what must be done to the subatomic particles to create a Neon atom?

Accepted Answer

Add 1 proton

Answer

Add 1 neutron

Answer

Remove 1 neutron

Answer

Add 2 protons

Question 18

What is the mass number of the atom shown?

Accepted Answer

21

Answer

22

Answer

20

Answer

9

Question 19

According to the figure, what must be done to create a fluorine atom with a mass number of 23 amu?

Accepted Answer

Add 2 neutrons

Answer

Add 2 protons

Answer

Add 1 proton

Answer

Add 1 neutron

Question 20

A high school chemistry teacher asks four student groups to determine the number of protons, neutrons and electrons (respectively) present in an isotope of  Titanium-46. Which student group provides the best answer?

Accepted Answer

Group one claims that there are 22 protons because this number identifies the element Ti, they also claim there are 24 neutrons because when the protons and neutrons are added the number equals the mass of the isotope, and there are 22 electrons because the isotope has no charge.

Answer

Group two claims the number of protons is 24 because the number of neutrons is always the same when subtracted from the mass which is 46, the number of neutrons would then equal 22, and the number of electrons is 24 because there is no charge.

Answer

Group three claims that there are 22 protons in an atom  of Ti so that means there are 26 neutrons because this matches the atomic mass on the periodic table and there are 22 electrons because every atom has the same amount of protons and electrons.

Answer

Group four claims there are 20 protons because the atom lost 2+ charges, the number of neutrons is 26 because when added the number of neutrons and protons should equal 46,  and there are 20 electrons because the number of electrons and protons should be the same.

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