Chapter 2 Atoms, Ions, and Molecules

Atom

The smallest particle that displays properties of an element; composed of electrons, protons, and neutrons (except in hydrogen)

Element

Substance composed of only one type of atom

Atomic Mass unit (AMU)

A unit of mass for atomic and molecular weights

Proton

A subatomic particle with a positive charge ; found in the focus of an atom

Neutron

A subatomic particle with a neutral charge; found in the nucleus of an atom.

Nucleus

Cellular structure housing DNA or u group of cell bodies in the central nervous system

Electron

Subatomic particle with a negative charge; found orbiting the nucleus of an atom.

Atomic number

Indicates the number of protons in one atom of a specific element. Value appears above each atomic symbol in the periodic table

Isotope

Atoms of an element that have a different number of neutrons

Radioisotope

Unstable isotope that emits high-energy radiation (eg, gamma rays) until it decays into a stable isotope.

Octet rule

Tendency of atoms to maintain an outer shell with eight electrons

Ionic compound

A chemical structure composed of ions

Cation

Ion with a positive charge; e.g, Na positive

Anion

Negatively charged ion; eg CI negative

Ionic bond

Chemical bond formed when a cation is electrostatically attracted to an anion

Salt

Substance formed by an ionic bond (eg, NaCI).

Molecule

A chemical structure composed of covalently bonded atoms.

Isomer

Molecules composed of the same number and types of atoms with a different arrangement;glucose, galactose

Glucose

A monosaccharide; primary nutrient source for cellular respiration

Nonpolar molecules

Molecules containing non polar covalent chemical bonds; hydrophobic

Amphipathic

Molecule that contains a hydrophobic region and a hydrophilic region

Hydrogen bond

A weak attraction formed between a partially positive hydrogen atom within a polar molecule and partially negative atom (e.g.,oxigen) within a polar molecule.

Organic molecule

Molecule containing Carbon atoms; e. Carbohydrates , proteins, lipids.

Solvent

Substance (e.g.,water) holding a solute in solution.

Solute

Substance dissolving in a solvent

Electrolyte

Chemical that dissociates when added to water and can conduct an electrical current; includes salts, bases, and acids

Acid

Substance that releases a hydrogen ion when added to a solution

Base

Substance that accepts a hydrogen ion

pH

Value indicating the relative hydrogen ion (H positive) concentration of a solution; expressed as a number between 0 and 14

Buffer

Substance that minimizes a change in pH after an acid or base is added.

Suspension

Mixture of solvent with large materials that do not dissolve; e.g., formed elements in blood

Colloid

Opaque mixture composed of water and solute (usually protein); substance with thyroid follicles

Solution

A homogeneous mixture composed of a solvent and a solute.

Molarity

Number of moles in 1 liter of solution.

Mole

Unit composed of 6.023×1023 particles; its mass in grams is equal to the element's atomic mass or the molecule's molecular mass

Monomers

Identical or similar molecules that repeat within polymer

Dehydration synthesis

Chemical reaction in which water is formed during formation of a complex molecule

Hydrolysis

Chemical reaction in which water is used during the breakdown of a complex molecule

Lipid

Group of hydrophobic macromolecules including triglycerides, phospholipids, steroids,and eicosanoids

Lipogenesis

Formation of triglycerides from glycerol and fatty acids

Lipólisis

Breakdown of triglycerides to glycerol and fatty acids

Eicosanoids

Local hormones derived from fatty acids

Carbohydrate

An organic molecule composed of carbon, hydrogen, and oxygen

Monosaccharide

The simplest carbohydrate molecules; e.g,.glucose, ribose.

Disaccharide

Carbohydrate composed of two monosaccharides; eg sucrose

Polysaccharide

Class of carbohydrates composed of three or more monosaccharide monomers; eg glycogen

Glycogen

Polysaccharide formed from glucose monomers

Glycogenesis

Formation of glycogen from glucose

Glycogenolysis

Breakdown of glycogen into glucose

Gloconeogenesis

Formation of glucose from a non carbohydrate source

Nucleotide

Building blocks of DNA and RNA; composed of a nitrogenous base, a phosphate group, and a sugar

Polypeptide

Chain of amino acids linked by peptide bonds

Protein

Biological macromolecule composed of one or more chains of amino acid monomers

Denaturation

A change in a protein's complex three dimensional shape that causes its biological activity to be impaired or to cease; may occur with changes in pH or increased temperature

An element's atomic number is determined by the number of ___in one atom of that element

Protons

Phospholipids are described as

Amphipathic

The number of neutrons in one atom can be determined by

Subtracting the atomic number from the atomic mass

A double covalent bond involves

The sharing of two pairs of electrons

Ionic bonds involve

Electrostatic interactions between anions and cations

An ion is an atom or group of atoms that has

Lost or gained an electron

Radioisotopes contain

An excess of neutrons

When diagramming an atom, how many electrons can fit in each of the shells beyond the intermost shell?

Eight

An individual hydrogen bond in a sample of water would be described as

Weak and intermolecular

Hydrogen bonds form between molecules containing —- —- bonds; the hydrogen bond is between a hydrogen atom of one molecule and partially _____ charged atom of another

Polar covalent; negatively