AP BIO: 1.1 Structure of Water and Hydrogen Bonding

Acid

An acid is any substance that donates protons or hydrogen ions to an aqueous solution, thereby increasing the hydronium ion concentration.

Adhesion

Adhesion is the attraction between different types of molecules.

Base

A base is a substance that can accept protons or donate a pair of valence electrons. In the context of biology, bases often refer to substances that can accept hydrogen ions and have a pH value greater than 7.

Chemical Formula

A chemical formula represents the proportion of atoms per element that make up a chemical compound using symbols from the periodic table.

Cohesion

Cohesion refers to the tendency for particles or molecules of the same substance to stick together.

Covalent Bonds

Covalent bonds are chemical bonds formed by sharing pairs of electrons between atoms.

Dipole Moment

A dipole moment is a measure of the polarity of a molecule, indicating how much positive and negative charge is separated within the molecule.

Dissociation of Water

The dissociation of water refers to the breaking down of H2O molecules into ions - specifically, one hydrogen ion (H+) and one hydroxide ion (OH-).

Electronegative Atom

An electronegative atom has a high affinity for electrons, meaning it has a tendency to attract shared electrons in a covalent bond towards itself.

Evaporative Cooling

Evaporative cooling is a process where the surface of an object becomes cooler during evaporation. This happens because the molecules with the highest kinetic energy are most likely to evaporate, leaving behind molecules with lower average kinetic energy and thus reducing temperature.

Hydrogen

Hydrogen is the first element on the periodic table. It's a colorless, odorless, tasteless gas that's highly flammable and combines with oxygen to form water.

Hydrogen bonding

Hydrogen bonding is a special type of intermolecular attraction between the hydrogen atom in a polar bond (particularly H-F, H-O, and H-N) and an electronegative atom nearby.

Hydrogen Ions

Hydrogen ions (H+) are single proton with no electrons and play crucial roles in chemical reactions, especially those involving acids and bases.

Hydronium Concentration

The hydronium concentration, often represented as [H3O+], is the measure of the amount of hydronium ions in a solution. It's used to determine the acidity or alkalinity (pH) of a solution.

Hydrophilic Substance

A hydrophilic substance is one that has an affinity for water; it can dissolve in or mix well with water.

Hydrophobic Substance

A hydrophobic substance is one that does not have an affinity for water; it does not dissolve in or mix well with water.

Lipids

Lipids are a group of naturally occurring molecules that include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E, and K), monoglycerides, diglycerides, triglycerides, phospholipids. They are an important part of living cells and serve as energy storage.

Logarithmic

In the context of biology, a logarithmic scale is often used to represent data that covers a large range of values in a compact way. It's a mathematical concept where each increment on the axis increases by a factor of 10.

Neutral pH

A neutral pH value is 7 on the pH scale, indicating neither acidity nor basicity. Pure water has a neutral pH.

Oxygen

Oxygen is a chemical element with symbol O and atomic number 8. It's essential for life on earth because it's part of the air we breathe and water we drink.

Partial Negative Charge

A partial negative charge occurs when an atom in a molecule attracts electrons more strongly than other atoms, causing the electrons to spend more time near that atom and giving it a slight negative charge.

Partial Positive Charge

This occurs when an atom shares its electron unequally with another atom in covalent bonding. The atom that pulls less strongly on shared electrons has partial positive charge due to lack of electron density.

PH Scale

The pH scale measures how acidic or basic an aqueous solution is, ranging from 0 (very acidic) to 14 (very basic), with 7 being neutral.

Polar Molecule

A polar molecule has uneven distribution of charge, meaning it has both positive and negative regions due to differences in electronegativity among its atoms.

Specific Heat

Specific heat refers to the amount of heat energy required to raise one gram of substance by one degree Celsius.

Surface Tension

Surface tension refers to the cohesive force at the surface of a liquid that allows it to resist external forces.

Transpiration

Transpiration is essentially plant sweat; it's when water vapor escapes from plants into the atmosphere through tiny pores called stomata.

Water Molecules

A water molecule is a chemical compound made up of two hydrogen atoms bonded to one oxygen atom. It's the most abundant molecule on Earth's surface.