1.1 - Matter and Its Classification

Matter vs. Energy

Matter is anything that has mass and occupies space, while energy is the capacity to do work or produce change.

What characteristics distinguish different types of matter?

Different types of matter are distinguished by their unique physical and chemical properties.

What are some properties of matter?

Physical properties are characteristics that can be observed or measured without changing the substance's chemical identity (e.g., color, density, melting point, boiling point, hardness). Chemical properties describe how a substance reacts or changes to form new substances (e.g., flammability, reactivity with acids/bases, oxidation).

Matter

Anything that has mass and occupies space.

Mass

A measure of the amount of matter in an object.

Pure Substance

A form of matter that has a constant composition and has consistent properties throughout the sample. It cannot be separated into simpler substances by physical means. Examples include elements and compounds.

Mixture

A substance composed of two or more pure substances that are physically combined and can be separated by physical means. Their properties can vary depending on the ratio of their components.

Elements

Pure substances that cannot be broken down into simpler substances by ordinary chemical means. Each element is defined by the number of protons in its atoms.

Electrolysis

The process of using electrical energy to drive a non-spontaneous chemical reaction, often used to decompose compounds into their constituent elements.

Periodic Table

A tabular arrangement of chemical elements, organized by their atomic number, electron configurations, and recurring chemical properties. It shows periodic trends.

Periodic Table - Row

A horizontal row on the periodic table, also known as a period. Elements in the same row have the same number of electron shells.

Periodic Table - Column

A vertical column on the periodic table, also known as a group or family. Elements in the same column have similar chemical properties due to having the same number of valence electrons.

Nonmetal

Elements that generally lack metallic properties, are typically poor conductors of heat and electricity, and can be brittle if solid. They tend to gain or share electrons in chemical reactions.

Metal

Elements that are typically good conductors of heat and electricity, are malleable and ductile, and possess a metallic luster. They tend to lose electrons in chemical reactions.

Compound

A pure substance composed of two or more different elements chemically bonded together in fixed proportions. Compounds can be broken down into simpler substances by chemical means.

Chemical Formula

A symbolic representation of a chemical compound, indicating the types of atoms and the number of each type in a molecule or formula unit (e.g., H2OH2​O for water, NaClNaCl for sodium chloride).

Homogenous Mixture (aka Solution)

A mixture in which the components are uniformly distributed throughout, appearing as a single phase. The composition is uniform at the macroscopic level.

Heterogenous Mixture 

A mixture in which the components are not uniformly distributed and can be easily distinguished, often existing in separate phases. The composition varies throughout the sample.

Atom

The smallest unit of an element that retains the chemical identity of that element. It consists of a nucleus (protons and neutrons) and orbiting electrons.

Molecule

A group of two or more atoms held together by chemical bonds. Molecules are the smallest particles of a compound or element that exists independently and retains all the chemical properties of that substance.

Macroscopic vs. Symbolic vs. Molecular Representations

1. Macroscopic: How matter appears to the naked eye (e.g., a glass of water, a piece of copper wire).

2. Symbolic: Representation using chemical symbols and equations (e.g., H2O(l)H2​O(l), Cu(s)Cu(s)).

3. Molecular: Representation at the atomic/molecular level, showing the arrangement and bonding of atoms (e.g., diagrams of water molecules or a lattice of copper atoms).

Physical State

The form in which matter exists, primarily solid, liquid, or gas, determined by temperature and pressure.

Characteristics of a Solid (s)

1. Particles are tightly packed in a fixed, orderly arrangement.

2. Particles vibrate in fixed positions.

3. Incompressible.

Characteristics of a Liquid (l)

1. Indefinite shape (takes the shape of its container) but definite volume.

2. Particles are close together but are free to move past one another.

3. Fluid, flows easily.

4. Slightly compressible.

Characteristics of a Gas (g)

1. Indefinite shape and indefinite volume (expands to fill its container).

2. Particles are far apart and move randomly and rapidly.

3. Highly compressible.

4. Fluid, flows easily.

What does (aq) stand for?

(aq) is an abbreviation for "aqueous," meaning dissolved in water. It indicates that a substance is present as ions or molecules in a water solution.