CIBI 3031 Terms to Know Instructor: Kristin Peterson

Chapter 2: Glossary of selected key terms (términos clave selectos)

acid / ácido

Any substance that, when dissolved in water, donates hydrogen ions.

atom / átomo

Smallest unit of an element that retains the element's properties.

base / base

Any substance that accepts hydrogen ions (H⁺) when dissolved in water; OH^- forms after this. Also, an organic compound with a single or double ring structure containing nitrogen.

buffer system / sistema amortiguador

A weak acid and the base that forms when it dissolves in water. The two work as a pair to counter slight shifts in pH.

chemical bond / enlace químico

A union between the electron structures of two or more atoms or ions.

cohesion / cohesión

Capacity to resist rupturing when placed under tension (stretched).

compound / compuesto

Molecule consisting of two or more elements in unvarying proportions (e.g., H₂O).

covalent bond / enlace covalente

Sharing of one or more electrons between atoms or groups of atoms. Nonpolar bonds share them equally. Polar bonds (slightly positive at one end, negative at the other) share them unequally.

electron / electrón

Negatively charged unit of matter, with particulate and wavelike properties, that occupies one of the orbitals around the atomic nucleus. Atoms gain, lose, or share electrons.

element / elemento

Fundamental form of matter that has mass, occupies space, and cannot be broken apart into a different form of matter, at least by ordinary physical or chemical means.

evaporation / evaporación

The conversion of a substance from a liquid state to a gaseous state by an input of heat energy.

hydrogen bond / puente de hidrógeno

Weak interaction between a small, highly electronegative atom and an H atom already taking part in a polar covalent bond in the same molecule or a different one.

hydrogen ion / ion hidrógenico

Free (or unbound) proton; one hydrogen atom that lost its electron and now bears a positive charge (H⁺).

hydrophilic substance / sustancia hidrofílica

A polar molecule or molecular region that easily dissolves in water (e.g., sugars).

hydrophobic substance / sustancia hidrofóbica

A nonpolar molecule or molecular region that strongly resists dissolving in water (e.g., oils).

ion / ion

An atom or a compound that has gained or lost one or more electrons and hence has acquired an overall negative or positive charge.

ionic bond / enlace iónico

Two ions being held together by the attraction of their opposite charge.

isotope / isótopo

One of two or more forms of an element's atoms that differ in the number of neutrons.

mixture / mezcla

Two or more elements or compounds intermingled in proportions that can and usually do vary.

molecule / molécula

Two or more atoms of the same or different elements joined by chemical bonds.

neutron / neutrón

Unit in the atomic nucleus that has mass but no electric charge.

pH scale / escala de pH

Measure of the concentration of free hydrogen ions (H⁺) in blood, water, and other solutions. pH 0 is the most acidic, 14 the most basic, and 7, neutral.

proton / protón

Positively charged particle; one or more in the nucleus of each atom. An unbound (free) proton is called a hydrogen ion (H⁺).

radioisotope / radioisótopo

Unstable atom (uneven number of protons and neutrons). It spontaneously emits particles and energy, and so decays into a different atom over a predictable time span.

salt / sal

Compound that releases ions other than H⁺ and OH^- in solution.

shell model / modelo de capas

Model of electron distribution in which all orbitals available to electrons of atoms occupy a nested series of shells.

solute / soluto

Any substance dissolved in a solution.

temperature / tempuratura

A measure of the kinetic energy of ions or molecules in a specified region.

tracer / marcador

Substance with an attached radioisotope that researchers can track after delivering it into a cell, body, ecosystem, or some other system. Its emissions are detected as it moves through a pathway or reaches a destination.