Chapter 1 - Atoms & Molecules

Matter

A physical substance that occupies space and has mass.

Element

A pure substance that cannot be created or broken down by ordinary chemical means.

Compound

A substance consisting of two or more elements combined in a fixed ratio, with characteristics different from those of its elements.

Molecule

Two or more atoms covalently bonded together.

Emerging properties

Characteristics that arise when elements combine in compounds.

Atomic Number

The number of protons in the nucleus of an atom.

Atomic Mass

The sum of the number of protons and neutrons in the nucleus of an atom.

Proton

A positively charged subatomic particle found in the nucleus of an atom.

Electron

A negatively charged subatomic particle that orbits the nucleus of an atom.

Neutron

A neutral subatomic particle found in the nucleus of an atom.

Covalent Bond

A chemical bond that occurs when two atoms share pairs of electrons.

Ionic Bond

A chemical bond formed when oppositely charged ions are attracted to each other.

Hydrogen Bond

A bond formed when a slightly positive hydrogen atom bonded to an electronegative atom is attracted to another electronegative atom.

Polar Covalent Bond

A bond that occurs when two atoms with different electronegativities share electrons unequally, resulting in a dipole.

Nonpolar Covalent Bond

A bond that occurs when two atoms share electrons equally, resulting in a symmetrical distribution of charge.

Valence Shell

The outermost electron shell of an atom.

Octet Rule

Atoms tend to gain, share, or lose electrons to achieve a full outer shell of eight electrons.

Inorganic Compound

A substance that does not contain both carbon and hydrogen.

Organic Compound

A substance that contains carbon-hydrogen (C-H) bonds.

Electrolyte

A substance that produces an electrical charge in solution, typically through ionization.

Atom

The smallest unit of an element that retains the unique properties of that element.

Electron Shell

An area of space around an atom's nucleus where electrons are grouped.

Cation

An ion with a net positive charge, due to the loss of electrons.

Anion

An ion with a net negative charge, due to the gain of electrons.

Dipole-ion Bond

A bond formed when a polar molecule is attracted to oppositely charged ions.

Carbon (C)

An essential element for life, forming the backbone of organic molecules.

Hydrogen (H)

A key element in water and organic compounds, crucial for energy transfer.

Oxygen (O)

Essential for cellular respiration and a component of water.

Nitrogen (N)

A critical component of amino acids and nucleic acids, necessary for protein synthesis.