Question 1

Which of the following is a nonmetal?

Accepted Answer

Nonmetals are typically located on the right side of the periodic table and have properties such as being brittle, dull, and poor conductors of heat and electricity. Bromine, with its location in group 17 (also known as the halogens) and its properties, is a nonmetal.

Question 2

A row of the periodic table is called a

Accepted Answer

A row of the periodic table is called a period. Groups are the columns of the periodic table, isotopic mixture refers to a mixture of different isotopes, family is not a commonly used term for describing the periodic table, and subshell refers to the specific energy level and orbital within an atom.

Question 3

Lithium forms compounds which are used in dry cells and storage batteries and in high-temperature lubricants. It has two naturally occurring isotopes, ⁶Li (isotopic mass = 6.015121 amu) and ⁷Li (isotopic mass = 7.016003 amu). Lithium has an atomic mass of 6.9409 amu. What is the percent abundance of lithium-6?

Accepted Answer

The atomic mass of lithium is a weighted average of its isotopes. Using the equation: (6.015121 * x) + (7.016003 * (1-x)) = 6.9409, solving for x gives the percent abundance of lithium-6 as approximately 7.503%.

Question 4

Bromine has two naturally occurring isotopes. ⁷⁹Br has a mass of 78.9 amu and accounts for 50.3% of bromine atoms. If the atomic mass of bromine is 79.9 amu, what is the mass of an atom of the second bromine isotope?

Accepted Answer

Let x be the mass of the second bromine isotope.

We know that the average atomic mass of bromine is 79.9 amu, and that one isotope (with a mass of 78.9 amu) accounts for 50.3% of bromine atoms.

Using this information, we can set up the following equation:

(0.503)(78.9 amu) + (0.497)x = 79.9 amu

Solving for x, we get:

x = (79.9 amu - (0.503)(78.9 amu))/0.497

x = 80.9 amu

Therefore, the mass of an atom of the second bromine isotope is 80.9 amu. The correct answer is D.

Question 5

Which one of the following statements about atoms and subatomic particles is correct?

Accepted Answer

A neutral atom contains equal numbers of protons and electrons. This is the basic concept of atomic structure, where the positive charge of the protons in the nucleus is balanced by the negative charge of the electrons in the electron cloud around the nucleus.

Question 6

Which of the following symbols does not represent an element?

Accepted Answer

HF is not a symbol for an element; it represents hydrofluoric acid, a compound made of hydrogen (H) and fluorine (F).

Question 7

In the modern periodic table, the order in which the elements are placed is based on

Accepted Answer

The modern periodic table is arranged in order of increasing atomic number, which is the number of protons in an atom's nucleus. This arrangement groups elements with similar chemical and physical properties together in columns, or groups, and also allows for the prediction of an element's properties based on its position in the table.

Question 8

Bromine is the only nonmetal that is a liquid at room temperature. Consider the isotope bromine-81,  . Select the combination which lists the correct atomic number, neutron number, and mass number, respectively.

Accepted Answer

The atomic number of bromine is 35, which is the number of protons in the nucleus. The neutron number can be found by subtracting the atomic number from the mass number. The isotope bromine-81 has a mass number of 81, so the neutron number is 81-35=46. Therefore, the correct combination is 35, 46, 81, which is given in choice A.

Question 9

Which of the following is a metal?

Accepted Answer

Thallium (Tl) is a metal with atomic number 81.

Question 10

An isotope of which of the following elements is chosen as a standard in measuring atomic mass?

Accepted Answer

Carbon is chosen as the standard in measuring atomic mass, specifically the carbon-12 isotope. This is because it provides a clear, consistent standard for comparison across all elements.

Question 11

Which of the following is a metalloid?

Accepted Answer

Germanium is a metalloid as it has properties of both metals and nonmetals. It is a semiconductor and is used in electronic devices like transistors.

Question 12

Silicon, which makes up about 25% of Earth's crust by mass, is used widely in the modern electronics industry. It has three naturally occurring isotopes, ²⁸Si, ²⁹Si, and ³⁰Si. Calculate the atomic mass of silicon.

Accepted Answer

To calculate the atomic mass of silicon, we need to take the weighted average of the isotopes' masses, where the weights are the isotopic abundances. From the periodic table, we know that the abundances of the three isotopes are 92.23%, 4.67%, and 3.10%, respectively. 
Atomic mass = (0.9223 x 28.0855 amu) + (0.0467 x 29.9255 amu) + (0.0310 x 29.9568 amu) 
Atomic mass = 28.0855 amu

Question 13

One amu is defined as

Accepted Answer

One amu is defined as 1/12 the mass of an atom of carbon-12.

Question 14

Atoms X, Y, Z, and R have the following nuclear compositions:      Which two are isotopes?

Accepted Answer

The answer of Atoms X, Y, Z, and R have...

Question 15

The chemical symbol for potassium is

Accepted Answer

The chemical symbol for potassium is K.

Question 16

Rutherford bombarded gold foil with alpha (α) particles and found that a small percentage of the particles were deflected. Which of the following was not accounted for by the model he proposed for the structure of atoms?

Accepted Answer

Rutherford's model did not account for the total mass of the atom because he believed that all of the mass was concentrated in the nucleus, with electrons having negligible mass. It was later discovered that the mass of the nucleus is only a small fraction of the total mass of the atom, with most of the mass coming from the electrons.

Question 17

A column of the periodic table is called a

Accepted Answer

A column of the periodic table is called a group.

Question 18

Which of the following elements are the least reactive?

Accepted Answer

Noble gases are the least reactive elements because their outermost energy level is completely filled with electrons, making them very stable and unlikely to gain or lose electrons.

Question 19

Which one of the following groups does not contain any metals?

Accepted Answer

C, S, As, and H are all nonmetals.

Question 20

When an atom is represented by the symbol  , the value of A is the

Accepted Answer

The answer of When an atom is represented by the...

Quiz 2: The Components of Matter