Chapter 2: Elements, Atoms, and Chemical Bonds

Vocabulary flashcards covering the basics of atomic structure, types of chemical bonds, and the nature of chemical reactions.

Element

A substance that cannot be broken down further by chemical reactions.

Key Elements

Carbon, hydrogen, nitrogen, and oxygen.

Atom

The smallest unit that retains the properties and therefore identity of the element.

Atomic Structure

Consists of a central nucleus with protons and neutrons, while electrons are located in electron shells, often described as "the cloud."

Protons

Subatomic particles that are positively charged, located in the nucleus, and determine an atom’s identity.

Neutrons

Subatomic particles that have a neutral charge, are located in the nucleus, and have the same mass as protons.

Electrons

Subatomic particles that carry a negative charge and are located in shells outside the nucleus.

Valence

The outermost shell of an atom.

Valence Electrons

Electrons in the outermost shell that may participate in chemical reactions.

Inert (Noble Gases)

The state of an atom when its valence shell is full, causing it to not participate in reactions.

Isotopes

Atoms with the same identity that have different masses but behave the same in chemical reactions; the term means "in the same place."

Stable Isotopes

Isotopes that do not lose subatomic particles.

Radioactive Isotopes

Isotopes that give off particles and energy.

Chemical Bonds

Attractions between atoms based on shared or transferred valence electrons.

Covalent Bonds

A pair of valence electrons that are shared between two atoms; these can be single, double, polar, or non-polar.

Molecule

Two or more covalent bonds held together.

Ionic Bond

A bond formed when electrons are completely transferred or stolen because one atom is much more electronegative than the other.

Cations

Positive ions formed in an ionic bond.

Anions

Negative ions formed in an ionic bond.

Electronegative

A property where an atom has a greater pull on electrons.

Polar Bond

A bond where electrons are shared unequally between atoms because one atom is more electronegative than the other.

Non-polar Bond

A bond where electrons are shared equally between atoms.

Strong Bonds

Bonds that are often covalent and are difficult to make and break.

Weak Bonds

Bonds that are usually attractions between separate molecules and are easy to make and break.

Hydrogen Bonds

Non-covalent attractions between a covalently bonded $H$ and a different electronegative atom.

Molecular Shape

Determined by valence electron arrangement and bonds between atoms; this determines how molecules work together.

Matter in Chemical Reactions

Matter cannot be created or destroyed, only rearranged as its composition changes.

Chemical Equilibrium

The point where forward and reverse reactions occur at the same rate, resulting in concentrations that stop changing.