Chapter 2.1 - 2.5 Atoms, Water, Carbon

Subatomic particle: Proton function

Contributes to the atomic mass and defines the atomic number/identity of an element.

Subatomic particle: Neutron charge and location

Neutral (0 charge)

Subatomic particle: Electron charge and location

Negative (-1) charge

Subatomic particle: Electron function

Determines chemical reactivity and how atoms interact or bond with each other.

Valence electrons definition

The electrons located in an atom's outermost energy shell.

Valence electrons function

Participate directly in forming chemical bonds and determine bonding capability.

Covalent bond definition

A chemical bond formed when two atoms share one or more pairs of electrons.

Ionic interaction definition

A chemical interaction formed when an electron is transferred from one atom to another, creating oppositely charged ions.

Nonpolar covalent bond definition

A covalent bond where electrons are shared approximately equally between atoms.

Polar covalent bond definition

A covalent bond where shared electrons spend more time around the more electronegative atom, resulting in unequal sharing.

Electronegativity definition

An atom's intrinsic ability to attract shared electrons toward itself.

Cause of water molecule polarity

Oxygen is significantly more electronegative than hydrogen, pulling shared electrons closer to its nucleus.

Partial charges on a water molecule

Oxygen holds a partial negative charge, while the two hydrogens hold partial positive charges.

Hydrogen bond definition

An attractive interaction between a partially positive hydrogen atom and an electronegative atom (typically O or N).

Biological function of hydrogen bonds in water

Creates cohesive forces that hold water molecules together and maintain fluid environments for life.

Mechanism of water as a solvent

Partial negative oxygen ($\delta^-$) surrounds positive ions, while partial positive hydrogens ($\delta^+$) surround negative ions, breaking ionic interactions.

Carbon outer shell structure

Contains 4 valence electrons and 4 vacancies in its outermost shell.

Carbon structural flexibility

Forms up to 4 covalent bonds, allowing molecules to take shapes of long chains, branches, and rings.

Carbon vs. Silicon stability comparison

Carbon is smaller, keeping valence electrons closer to the nucleus to form stable bonds that withstand biological heat.

Proteins biological function

Highly versatile macromolecules that act as enzymes, structural components, and cellular machinery.

Nucleic acids biological function

Information-carrying macromolecules (DNA and RNA) responsible for genetic storage and transmission.

Lipids biological function

Serve as long-term energy fuel reserves and form semi-permeable cellular barriers (membranes).

Carbohydrates biological function

Serve as primary cellular energy fuel and act as structural or signaling markers.