Chapter 3 Chemistry: Matter, Energy, and Their Properties

What is matter?

Matter is anything that occupies space and has mass.

What are the common states of matter?

Solid, liquid, and gas.

How can water exist in different states?

Water exists as ice (solid), water (liquid), and steam (gas).

What is the composition of matter?

Matter is composed of atoms and molecules.

What are atoms?

Atoms are submicroscopic particles that are the fundamental building blocks of matter.

What are molecules?

Molecules are two or more atoms joined together in specific geometric arrangements.

What is a crystalline solid?

A crystalline solid has atoms or molecules arranged in geometric patterns with long-range, repeating order.

What is an amorphous solid?

An amorphous solid has atoms or molecules that do not have long-range order.

What happens to water molecules in ice?

In ice, water molecules are closely spaced and vibrate about a fixed point without moving relative to one another.

What happens to water molecules in liquid water?

In liquid water, molecules are closely spaced but can move around and past each other.

What happens to water molecules in steam?

In steam, water molecules are separated by large distances and do not interact significantly with one another.

What is the role of a scanning tunneling microscope (STM)?

An STM creates images by scanning a surface with a tip of atomic dimensions, distinguishing individual atoms.

What does DNA encode?

DNA encodes the hereditary material and operating instructions for most cells in living organisms.

What is an example of a crystalline solid?

Salt and diamond are examples of crystalline solids.

What is an example of an amorphous solid?

Glass is an example of an amorphous solid.

What distinguishes independent atomic particles in aluminum?

In aluminum, the atoms exist as independent particles.

What is the significance of molecular structures?

Molecular structures determine the properties and behavior of different types of matter.

How have recent advances in microscopy impacted our understanding of matter?

Recent advances allow us to image the atoms and molecules that compose matter.

What characterizes an amorphous solid?

Atoms do not have any long-range order.

What is the arrangement of atoms in a crystalline solid?

Atoms are arranged in a well-ordered, geometric pattern.

How do liquids behave in terms of volume and shape?

Liquids have a fixed volume but assume the shape of their containers.

What is the atomic arrangement in liquids?

Atoms or molecules are close to each other but can move around each other.

What are some examples of liquid matter?

Water, gasoline, alcohol, and mercury.

What is a key characteristic of gases?

Gases are compressible and assume the shape and volume of their containers.

What is the atomic arrangement in gases?

Atoms or molecules are separated by large distances and are free to move relative to one another.

What is a pure substance?

A substance composed of only one type of atom or molecule.

What is a mixture?

A combination of two or more different types of atoms or molecules in variable proportions.

What defines an element?

A pure substance that cannot be broken down into simpler substances.

What is a compound?

A pure substance composed of two or more elements in fixed definite proportions.

Can compounds be decomposed into simpler substances?

Yes, compounds can be decomposed into simpler substances.

What is an example of a compound?

Water (H2O), table salt (NaCl), and sugar (C12H22O11).

What distinguishes a homogeneous mixture from a heterogeneous mixture?

A homogeneous mixture has a uniform composition, while a heterogeneous mixture has a non-uniform composition.

What is a physical property?

A characteristic that a substance displays without changing its composition.

What is a chemical property?

A characteristic that a substance displays only through changing its composition.

What happens to water when it boils?

It changes from a liquid to a gas, but the composition remains the same.

What is a physical change?

A change that alters the appearance of a substance without changing its composition.

What is a chemical change?

A change that results in the formation of new substances with different compositions.

What occurs during the melting of ice?

Ice melts into liquid water, which is a physical change since the composition remains the same.

What is an example of a chemical change?

Copper turning green when exposed to air due to the formation of new compounds.

What is the boiling point of water?

100 °C.

What are the two types of mixtures?

Homogeneous mixtures and heterogeneous mixtures.

What is the difference between a compound and a mixture?

A compound is chemically united in fixed proportions, while a mixture is not chemically united.

What happens to iron when it rusts?

It changes from iron to iron oxide.

What are reactants in a chemical reaction?

The substances present before the chemical change.

What are products in a chemical reaction?

The substances present after the chemical change.

How do physical changes differ from chemical changes?

In physical changes, the atoms do not change their fundamental associations, while in chemical changes, atoms change their associations, resulting in new substances.

What is an example of a physical change?

Vaporization of butane from liquid to gas.

What does the Law of Conservation of Mass state?

Matter is neither created nor destroyed in a chemical reaction; the total amount of matter remains constant.

What is energy defined as in chemistry?

The capacity to do work.

What is the Law of Conservation of Energy?

Energy is neither created nor destroyed; the total amount of energy is constant.

What are the two main forms of energy in matter?

Kinetic energy (energy of motion) and potential energy (energy of position or composition).

What is the SI unit of energy?

The joule (J).

What is a calorie?

The amount of energy required to raise the temperature of 1 g of water by 1 °C.

What is the difference between exothermic and endothermic reactions?

Exothermic reactions release energy, while endothermic reactions absorb energy.

What is thermal energy?

The energy associated with the random motions of atoms and molecules in matter.

How is temperature related to thermal energy?

Temperature is a measure of the thermal energy of matter; the hotter an object, the greater the random motion of its atoms and molecules.

What is the difference between heat and temperature?

Heat is the transfer of thermal energy caused by a temperature difference, while temperature measures the thermal energy of matter.

What does the Fahrenheit scale assign to the freezing point of water?

32 °F.

What does the Celsius scale assign to the boiling point of water?

100 °C.

What is absolute zero on the Kelvin scale?

0 K, the temperature at which molecular motion virtually stops.

What happens to potential energy when a weight is lifted?

It has high potential energy and will tend to fall to lower its potential energy.

Why are substances with high potential energy often unstable?

They tend to undergo changes that lower their potential energy.

What is an example of a substance with high potential energy?

TNT (trinitrotoluene), which is explosive due to its high potential energy.

What is the average cost of residential electricity in the United States per kilowatt-hour?

About $0.12 per kilowatt-hour.

How many joules are in a candy bar that contains 225 Cal of nutritional energy?

225 Cal is equivalent to approximately 942,000 joules (since 1 Cal = 4,184 joules).

What is room temperature in Kelvin?

Approximately 295 K.

How does the size of a Fahrenheit degree compare to a Celsius degree?

The Fahrenheit degree is five-ninths the size of a Celsius degree.

Are Celsius and Kelvin degrees the same size?

Yes, the Celsius degree and the Kelvin degree are the same size.

What is heat capacity?

The quantity of heat required to change the temperature of a given amount of substance by 1 °C.

What is specific heat capacity?

The heat capacity when the amount of substance is expressed in grams, measured in joules per gram per degree Celsius (J/g °C).

Which substance has the highest specific heat capacity?

Water.

What does 'q' represent in heat capacity equations?

The amount of heat in joules.

What does 'm' stand for in the heat capacity formula?

The mass of the substance in grams.

What does 'C' represent in the context of heat capacity?

The specific heat capacity in joules per gram per degree Celsius.

What does 'T' indicate in heat capacity calculations?

The temperature change in Celsius.

What does the symbol Δ represent?

It means 'change in', so ΔT means the change in temperature.

At what temperature does gallium melt?

Gallium melts at 29.9 °C.

How much heat must 2.5 g of gallium absorb to raise its temperature from 25.0 °C to 29.9 °C?

The specific heat capacity of gallium is 0.372 J/g °C.

What is the additional heat required to melt gallium once it reaches the melting point?

An additional 200 J is needed to melt 2.5 g of gallium.

What are the two types of pure matter?

Elements and compounds.

What is a homogeneous mixture?

A mixture having the same composition throughout.

What is a heterogeneous mixture?

A mixture having a composition that varies from region to region.

What is the law of conservation of mass?

In a chemical change, the sum of the masses of the reactants must equal the sum of the masses of the products.

What are the units of energy?

Joules (J), calories (cal), nutritional Calories (Cal), and kilowatt-hours (kWh).

What type of chemical reaction emits energy?

Exothermic reactions.

What type of chemical reaction absorbs energy?

Endothermic reactions.

How is temperature related to the motion of molecules?

Temperature is related to the random motions of the molecules and atoms.

What are the three temperature scales?

Fahrenheit (°F), Celsius (°C), and Kelvin (K).