Chemistry Exam 1 Review

Matter is described as anything that has mass and occupies space, making it different from energy, time, and emotions which do not have physical properties in the same way.

Energy is defined as the ability to cause changes in matter, such as motion, heat, or chemical reactions.

The scientific method starts with making observations, then forming a hypothesis, followed by conducting experiments to test the hypothesis, and finally establishing a scientific law or theory based on the results.

A law is considered a generally observed natural phenomenon as it describes a consistent and predictable behavior or occurrence in the natural world.

A theory is a well-substantiated explanation based on observation, experimentation, and reasoning. It is not a wild guess, proven fact, or mere opinion.

Solids have a defined shape, volume, and high density, unlike liquids and gases which do not exhibit these characteristics.

Liquids have an indefinite shape, meaning they take the shape of the container they are in; they have a definite volume, meaning they do not expand to fill the container completely; and they have a high density compared to gases.

Gases do not have a definite shape or volume and have low density compared to liquids and solids.

Sublimination is the process of a substance transitioning directly from a solid state to a gas state without passing through the liquid state. This is a unique property exhibited by certain substances.

A substance refers to a sample of matter that cannot be broken down into simpler substances by physical means. It is a fundamental concept in chemistry to understand the nature of different materials.

An element is a pure substance made up of only one type of atom and cannot be broken down into simpler substances by chemical means. Compounds are made up of two or more different elements chemically combined, mixtures are made up of two or more substances physically mixed together, and solutions are mixtures where one substance is dissolved in another.

A compound is defined as a substance that is composed of two or more different elements that are chemically combined together. It is distinguishable from a mixture where the elements are not chemically bonded.

Molecular compounds are composed of nonmetals covalently bonded, sharing electrons and having weak attractions between molecules. They are typically in the form of gases, liquids, or low melting point solids.

Diatomic elements exist as molecules composed of two atoms of the same element. The correct answer includes H2, N2, O2, F2, Cl2, Br2, and I2, while the incorrect answers are helium (He), lithium (Li) which is not diatomic, and sodium chloride (NaCl) which is a compound composed of two different elements.

Noble gases are inert elements that exist as monatomic atoms, meaning they are single atoms rather than molecules or compounds.

Metals typically have delocalized bonding, where electrons are free to move throughout the material.

Strong acids completely dissociate into ions when dissolved in water, resulting in a high concentration of H+ ions.

Weak acids only partially ionize in aqueous solutions, unlike strong acids that fully ionize. They are also capable of conducting electricity to a lesser extent compared to strong acids.

Strong bases are typically metal hydroxides that are ionic in nature. Transition metal hydroxides also form insoluble bases, but non-metal hydroxides, organic bases, and gaseous bases are not classified as strong bases.

Weak bases are molecular compounds that do not fully dissociate in water compared to strong bases, which are ionic compounds that completely dissociate in water. Inorganic acids are not bases, and strong bases exhibit high levels of dissociation.

The Law of Conservation of Mass states that mass is neither created nor destroyed in a chemical reaction. This principle was formulated by Antoine Lavoisier in the late 18th century, revolutionizing the field of chemistry.

J. L. Proust is credited with the discovery of the Law of Definite Proportions or Law of Constant Composition, which states that a given compound always contains exactly the same proportions of elements by mass.

The Law of Multiple Proportions was proposed by J. Dalton, stating that when two elements form a series of compounds, their mass ratios can be reduced to small whole numbers.

Protons are subatomic particles with a mass of 1 and a positive charge of +1.

Neutrons are subatomic particles with no net electric charge and a mass slightly larger than that of protons. This makes them essential for holding atomic nuclei together.

Electrons are subatomic particles with a mass of approximately 0 and a charge of -1. Any other combination of mass and charge would not accurately describe an electron.