Chemical Foundation of Life - Vocabulary Flashcards

Flashcards covering key biological chemistry concepts including atomic structure, valence electrons, Lewis structures, molecular shapes, polarity, and chemical reaction dynamics.

Bohr model

A simple atomic model in which electrons circle around a central nucleus that contains protons and neutrons.

First electron shell

The energy level closest to the atomic nucleus, which can hold a maximum of two electrons.

Octet rule

The principle that the second and third electron shells of an atom can fill up to a maximum of eight electrons each.

Valence electrons

The electrons located in the outermost shell or energy level of an atom.

Single bond

A covalent bond formed when one pair of electrons is shared between two atoms.

Double bond

A covalent bond formed when two pairs of electrons are shared between two atoms, represented by two lines in a Lewis structure.

Triple bond

A strong covalent bond formed when three pairs of electrons are shared between two atoms, such as in diatomic nitrogen gas ($N_2$).

Lone pair

A pair of valence electrons that are paired up in an atom's shell and are not shared with another atom.

Polarity

The property describing how electrons are shared or distributed between atoms in a molecule.

Bent molecular shape

A three-dimensional geometry, such as in water ($H_2O$), where repelling lone electron pairs push bonded atoms downward, creating a non-linear arrangement.

Linear molecular shape

A three-dimensional molecular geometry, such as in carbon dioxide ($CO_2$), where atoms line up on opposite ends and equal electron pulls cancel out.

Tetrahedral molecular shape

A three-dimensional molecular geometry, such as in methane ($CH_4$), where electrons are shared equally around the central atom.

Chemical reaction

A process in which two or more atoms bond together to form molecules or existing bonds between atoms break apart.

Law of conservation of matter

The law stating that matter cannot be created or destroyed, requiring a chemical equation to have an equal number of each type of atom on both sides.

Reversible reaction

A chemical reaction that can proceed in both the forward direction to form products and the reverse direction to re-form reactants.

Law of mass action

The principle stating that higher concentrations of reacting molecules increase molecular collisions, driving the direction and rate of a reversible reaction.

Ionic compound

A compound, such as magnesium chloride ($MgCl_2$), that is held together by ionic bonds between ions.

Polar molecule

A molecule with an uneven distribution of electron density, resulting in partial positive and partial negative charged regions.