Notes for chem

Pure Substance

A material made of only one type of particle.

Example of a Pure Substance

Distilled water (H₂O) or copper (Cu).

Mixture

A combination of two or more substances that retain their individual properties.

Example of a Mixture

Saltwater (a mixture of salt and water) or salad (a mixture of various vegetables).

Homogeneous Mixture

A mixture that has a uniform composition throughout.

Example of a Homogeneous Mixture

Air or vinegar.

Heterogeneous Mixture

A mixture that consists of visibly different substances or phases.

Example of a Heterogeneous Mixture

Sand and iron filings or a salad.

Location of Metals on the Periodic Table

Metals are located on the left side and the center.

Location of Nonmetals on the Periodic Table

Nonmetals are located on the right side.

Element

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

Compound

A substance formed when two or more elements are chemically bonded together.

Molecule

The smallest unit of a compound that retains the properties of that compound.

Example of a Molecule

H₂O.

Physical Properties

Characteristics that can be observed or measured without altering the substance's composition.

Examples of Physical Properties

Color, odor, melting point, and solubility.

Chemical Properties

Characteristics that describe a substance's ability to undergo changes that transform it into different substances.

Example of a Chemical Property

Reactivity with acids or flammability.

Periodic Table Arrangement

Organized by increasing atomic number.

Similar Chemical Properties

Elements in the same column (family) share similar chemical properties.

Same Electron Shells

Elements in the same row (period) have the same number of electron shells.

Atomic Structure

An atom is made up of protons, neutrons, and electrons.

Atomic Number (Z)

Represents the number of protons in an atom.

Valence Shells

The number of valence shells corresponds to the period number of an element.

Bohr Diagrams

A visual representation of an atom showing its nucleus and the arrangement of electrons in different energy levels.

Naming Compounds

To determine the charge on a compound, consider the oxidation states of elements.

Example of a Compound

NaCl consists of Na⁺ and Cl⁻.

Ions

The only thing changing in ions are the electrons.

Cations and Anions

Positively charged cations or negatively charged anions form when electrons are lost or gained.

Ionic Bonding

Involves transfer of electrons from one atom to another resulting in positive and negative ions.

Covalent Bonding

Involves sharing of electrons between atoms.

Goal of Ionic and Covalent Bonding

Both types of bonding generally aim to achieve full valence shells.

Result of Ionic and Covalent Bonding

Both types of bonding result in compounds.