Unit 7

What is a chemical?

A substance that has a definite and uniform composition.

Define matter.

Anything that has mass and takes up space.

What does weight measure?

The amount of matter and the effects of Earth's gravitational pull on that matter.

How is mass defined?

A measurement that reflects the amount of matter in a quantitative form.

What are physical properties of matter?

Characteristics that can be observed or measured without changing the sample's composition.

What are extensive properties?

Properties dependent on the amount of substance present, such as mass, length, and volume.

What are intensive properties?

Properties independent of the amount of substance present, such as density.

What defines a chemical property of matter?

The ability or inability of a substance to combine with or change into one or more other substances.

Give an example of a chemical property.

Iron forming rust when combined with oxygen in the air.

What is a physical change?

A change that alters the physical properties of a substance but does not change its composition.

What is a chemical change?

A process involving one or more substances changing into new substances, also called a chemical reaction.

What does the law of conservation of mass state?

Mass is neither created nor destroyed during a chemical reaction.

What are elements?

Pure substances that cannot be broken down into simpler substances by physical or chemical means.

What is the purpose of the periodic table?

To organize all known elements into a grid by increasing atomic number.

Define compounds.

Substances made up of two or more different elements combined chemically in a fixed ratio.

What is a mixture?

A physical blend of two or more substances in any proportion where individual properties are retained.

Differentiate between heterogeneous and homogeneous mixtures.

Heterogeneous mixtures do not have a uniform composition, while homogeneous mixtures have a uniform composition throughout.

What is filtration?

A technique that uses a porous basin to separate a solid from a liquid.

What is distillation?

A physical separation technique based on differences in boiling points of substances.

What is sublimation?

The process during which a solid changes to vapor without melting.

What is chromatography?

A technique that separates components of a mixture based on their ability to travel on a fixed substance.

What is crystallization?

A separation technique that results in the formation of pure solid particles of a substance.

Describe metals.

Elements that are shiny, solid at room temperature, good conductors of heat and electricity, and mostly malleable and ductile.

What are alkali metals?

Very reactive metals that usually exist as compounds with other elements.

What are nonmetals?

Elements that are generally gases or brittle, dull-looking solids and poor conductors of heat and electricity.

What are noble gases?

Extremely unreactive elements found in group 18 of the periodic table.

What are metalloids?

Elements that have physical and chemical properties of both metals and nonmetals.

What determines a substance's state of matter?

The balance between large-scale attractive forces and kinetic energy.

What is the kinetic molecular theory?

It states that all atoms/molecules are in constant motion, and motion is measured in terms of kinetic energy.

What happens to particles in solids?

Large-scale attractive forces outweigh kinetic energy, resulting in fixed positions and high density.

What characterizes liquids?

Large-scale attractive forces are approximately equal to kinetic energy, allowing particles to move past each other.

What defines gases?

Kinetic energy outweighs large-scale attractive forces, resulting in total disorder and low density.

What are phase changes?

Transitions between states of matter, such as melting, freezing, vaporization, condensation, sublimation, and deposition.

What is molar enthalpy?

The heat needed to complete a phase change for one mole of a substance.