According to the wave-mechanical model of the atom, an orbital is a region of the most probable location of

Which particles have approximately the same mass?

During a flame test, a lithium salt produces a characteristic red flame. This red color is produced when electrons in excited lithium atoms

Compared to the energy and charge of the electrons in the first shell of a Be atom, the electrons in the second shell of this atom have

Which quantity can vary among atoms of the same element?

Which substance have atoms of the same element but different molecular structures?

An atom that has 13 proton and 15 neutron is an isotope of the element

Which elements have the most similar chemical properties?

In a bond between an atom of carbon an an atom of fluorine, the fluorine atom has a

Which list includes three types of chemical formulas for organic compounds?

A sample of CO₂ (s) and a sample of CO₂ (g) differ in their

Which statement defines the temperature of a sample of matter?

For a chemical reaction, the difference between the potential energy of the products and the potential energy of the reactants is equal to the

Which equation represents sublimation?

Which statement describes the particles of an ideal gas, based on the kinetic molecular theory?

Two grams of potassium chloride are completely dissolved in a sample of water in a beaker. This solution is classified as

Which compound has the strongest hydrogen bonding between its molecules?

Powdered sulfur is yellow and powdered iron is gray. When powered sulfur and powdered iron are mixed at 20ºC, the powdered iron

An effective collision between reactant particles requires the particles to have proper

Which term is defined as a measure of the disorder of a system?

Which process is used to determine the concentration of an acid?

The compounds CH₃OCH₃ and CH₃CH₂OH have different functional groups. Therefore, these compounds have different

Which term identifies the half-reaction that occurs at the anode of an operating electrochemical cell?

During the operation of a voltaic cell, the cell produces

In which type of chemical reaction are electrons transferred?

A substance that dissolves in water and produces hydronium ions as the only positive ions in the solution is classified as

According to one acid-base theory, a base is an

Which compound is an electrolyte?

Which term identifies a type of nuclear reaction?

Which radioisotopes have the same decay mode and have half-lives greater than 1 hour?

The diagram below represents the bright-line spectra of four elements and a bright-line spectrum produced by a mixture of three of these elements.

Which element is not present in the mixture?

What is the overall charge of an ion that has 12 protons, 10 electrons, and 14 neutrons?

As the elements in Period 3 are considered in order of increasing atomic number, there is a general decrease in

Which electron configuration represents the electrons of sulfur atom in an excited state?

Given the word equation:

sodium chlorate → sodium chloride + oxygen

Which type of chemical reaction is represented by this equation?

Which compound has the highest percent composition by mass of strontium?

Given the formula for hydrazine:

How many pairs of electrons are shared between the two nitrogen atoms?

Which formulas represent one ionic compound and one molecular compound?

Which Kelvin temperature is equal to 200. ºC?

A 10.0-gram sample of H₂O(l) at 23.0ºC absorbs 209 joules of heat. What is the final temperature of the H₂O(l) sample?

Given the equation representing a system at equilibrium:

AgCl(s) + H₂O(l) ⇔ Ag⁺(aq) + Cl^– (aq)

When the concentration of Cl^–(aq) is increased, the concentration of Ag⁺(aq)

Which particle diagram represents a sample of matter that can not be broken down by chemical means?

Which formula represents an unsaturated hydrocarbon?

When the pH of a solution is changed from 4 to 3, the hydronium ion concentration concentration of the solution

Three samples of the same solution were tested, each with a different indicator. All three indicators, bromothymol blue, bromocresol green, and thymol blue appear blue if the pH of the solution is

A 10.0-milliliter sample of NaOH(aq) is neutralized by 40.0 milliliters of 0.50 M HCl. What is the molarity of the NaOH(aq)?

Radiation is spontaneously emitted from hydrogen-3 nuclei, but radiation is not spontaneously emmited from hydrogen-1 nuclei or hydrogen-2 nuclei. Which hydrogen nuclei are stable?

Given the equation representing a nuclear reaction in which X represents a nuclide:

After decaying for 48 hours, 1/16 of the original mass of a radioisotope sample remains unchanged. What is the half-life of this radioisotope?

Which balanced equation represents nuclear fusion?

When magnesium is ignited in air, the magnesium reacts with oxygen and nitrogen. The reaction between magnesium and nitrogen is represented by the unbalanced equationbelow

Mg(s) + N₂(g) → Mg₃N₂(s)

Balance the equation below for the reaction between magnesium and nitrogen using the smallest whole-number coefficients.

_____Mg(s) + _______N₂(g) → ________ Mg₃N₂(s)

In the ground state which noble gas has atoms with the same electronic configuration as a magnesium ion?

Explain in terms of electrons, why an atom of the metal in this reaction forms an ion that has a smaller radius than its atom.

The balanced equation below represents a reaction.
O₂(g) energy → O(g) + O(g)

Identify the chemical bond in a molecule of the reactant.

Draw a Lewis electron-dot diagram of one oxygen atom.

The balanced equation below represents a reaction.
O₂(g) energy → O(g) + O(g)

Explain why in terms of bonds, why energy is absorbed during this reaction.

Starting as a solid at 25°C, a sample of H₂O is heated at a constant rate until the  sample is at -25°C. This heating occurs at standard pressure. The graph below represents the relationship between temperature and heat added to the sample.

Describe what happens to both the potential and  the average kinetic energy of the molecules in the H₂O sample during interval AB.

Starting as a solid at 25°C, a sample of H₂O is heated at a constant rate until the sample is at 125°C. This heating occurs at standard pressure. The graph below represents the relationship between temperature and heat added to the sample.

Using the graph determine the total amount of heat added to the sample during the interval CD.

Starting as a solid at 25°C, a sample of H₂O is heated at a constant rate until the sample is at 125°C. This heating occurs at standard pressure. The graph below represents the relationship between temperature and heat added to the sample.

Explain, in terms of heat of fusion and heat of vaporization, why the heat added during interval DE is greater than the heat added during interval BC for this sample of water.

Cylinder A has a movable piston and contains hydrogen gas. An identical cylinder, B, contains methane gas. The diagram below represents these cylinders and the conditions of pressure, volume, and temperature of the gas in each cylinder.

Compare the total number of gas molecules in cylinder A to the total number of gas molecules in cylinder B.

Cylinder A has a movable piston and contains hydrogen gas. An identical cylinder, B, contains methane gas. The diagram below represents these cylinders and the conditions of pressure, volume, and temperature of the gas in each cylinder.

State a change in temperature and a change in pressure that will cause the gas in  cylinder A to behave more like an ideal gas.

Cylinder A has a movable piston and contains hydrogen gas. An identical cylinder, B, contains methane gas. The diagram below represents these cylinders and the conditions of pressure, volume, and temperature of the gas in each cylinder.

Show a numerical setup for calculating the volume of the gas in cylinder B at STP.

There are several isomers of C₆H₁₄. The formulas and boiling points for two of these isomers are given in the table below.

Identify the homologous series to which these isomers belong.

There are several isomers of C₆H₁₄. The formulas and boiling points for two of these isomers are given in the table below.

Write the empirical formula for isomer 1.

There are several isomers of C₆H₁₄. The formulas and boiling points for two of these isomers are given in the table below.

Explain in terms of intermolecular forces, why isomer 2 boils at a lower temperature than isomer 1.

Before atomic numbers were known, Mendeleev developed a classification system for the 63 elements known in 1872, using oxide formulas and atomic masses. He used an R in the oxide formulas to represent any element in each group. The atomic mass was listed in
parentheses after the symbol of each element. A modified version of Mendeleev’s classification system is shown in the table below.

Identify one characteristic used by Mendeleev to develop his classification system of the elements.

Before atomic numbers were known, Mendeleev developed a classification system for the 63 elements known in 1872, using oxide formulas and atomic masses. He used an R in the oxide formulas to represent any element in each group. The atomic mass was listed in
parentheses after the symbol of each element. A modified version of Mendeleev’s classification system is shown in the table below.

Based on Mendeleev’s oxide formula, what is the number of electrons lost by each atom of the elements in Group III?

Before atomic numbers were known, Mendeleev developed a classification system for the 63 elements known in 1872, using oxide formulas and atomic masses. He used an R in the oxide formulas to represent any element in each group. The atomic mass was listed in
parentheses after the symbol of each element. A modified version of Mendeleev’s classification system is shown in the table below.

Based on Table J, identify the least active metal listed in Group I on Mendeleev’s table

Before atomic numbers were known, Mendeleev developed a classification system for the 63 elements known in 1872, using oxide formulas and atomic masses. He used an R in the oxide formulas to represent any element in each group. The atomic mass was listed in
parentheses after the symbol of each element. A modified version of Mendeleev’s classification system is shown in the table below.

Explain, in terms of chemical reactivity, why the elements in Group 18 on the modern Periodic Table were not identified by Mendeleev at that time.

In a laboratory apparatus, a sample of lead(II) oxide reacts with hydrogen gas at high temperature. The products of this reaction are liquid lead and water vapor. As the reaction proceeds, water vapor and excess hydrogen gas leave the glass tube. The diagram and
balanced equation below represent this reaction.

Determine the change in oxidation number for the hydrogen that reacts.

In a laboratory apparatus, a sample of lead(II) oxide reacts with hydrogen gas at high temperature. The products of this reaction are liquid lead and water vapor. As the reaction proceeds, water vapor and excess hydrogen gas leave the glass tube. The diagram and
balanced equation below represent this reaction.

Write a balanced half-reaction equation for the reduction of the Pb2 ions in this  reaction.

In a laboratory apparatus, a sample of lead(II) oxide reacts with hydrogen gas at high temperature. The products of this reaction are liquid lead and water vapor. As the reaction proceeds, water vapor and excess hydrogen gas leave the glass tube. The diagram and
balanced equation below represent this reaction.

Explain why the reaction that occurs in the glass tube can not reach equilibrium?

In a laboratory apparatus, a sample of lead(II) oxide reacts with hydrogen gas at high temperature. The products of this reaction are liquid lead and water vapor. As the reaction proceeds, water vapor and excess hydrogen gas leave the glass tube. The diagram and
balanced equation below represent this reaction.

State one change in reaction conditions, other than adding a catalyst, that would cause the rate of this reaction to increase.

In the late 19th century, the Hall-Herroult process was invented as an inexpensive way to produce aluminum. In this process, Al₂O₃(ℓ) extracted from bauxite is dissolved in Na₃AlF₆(ℓ) in a graphite-lined tank, as shown in the diagram below. The products are  carbon dioxide and molten aluminum metal.

Compare the chemical properties of a 300.-kilogram sample of Al₂O₃(ℓ) with the chemical properties of a 600.-kilogram sample of Al₂O₃(ℓ).

In the late 19th century, the Hall-Herroult process was invented as an inexpensive way to produce aluminum. In this process, Al₂O₃(ℓ) extracted from bauxite is dissolved in Na₃AlF₆(ℓ) in a graphite-lined tank, as shown in the diagram below. The products are  carbon dioxide and molten aluminum metal.

Write the chemical name for the liquid compound dissolved in the Na₃AlF₆(ℓ).

In the late 19th century, the Hall-Herroult process was invented as an inexpensive way to produce aluminum. In this process, Al₂O₃(ℓ) extracted from bauxite is dissolved in Na₃AlF₆(ℓ) in a graphite-lined tank, as shown in the diagram below. The products are  carbon dioxide and molten aluminum metal.

What is the melting point of the substance that collects at the bottom of the tank?

In the late 19th century, the Hall-Herroult process was invented as an inexpensive way to produce aluminum. In this process, Al₂O₃(ℓ) extracted from bauxite is dissolved in Na₃AlF₆(ℓ) in a graphite-lined tank, as shown in the diagram below. The products are  carbon dioxide and molten aluminum metal.

Compare the densities of the Al(ℓ) with the density of the mixture of Al₂O₃(ℓ) and Na₃AlF₆(ℓ).