Bio 201 Chapter 2: Atoms & Molecules

Front 1

Element

Back 1

A substance that cannot be changed to a simpler substance by a normal chemical reaction.

Front 2

Atom

Back 2

The smallest quantity of an element that retains the chemical properties of an element.

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Nucleus

Back 3

The central region of an atom that contains protons and neutrons.

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Proton

Back 4

A particle present in the nuclei of all atoms that is postively charged and has a mass of one atomic mass unit.

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Electron

Back 5

A particle that is negatively charged with a negligible mass; is located outside the atomic nucleus.

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Neutron

Back 6

An electrically neutral particle with a mass of one atomic mass unit; found in the atomic nucleus.

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Atomic Number

Back 7

The number of protons in the atomic nucleus of an atom, which uniquely identifies the element to which the atom corresponds.

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Atomic Mass

Back 8

The total number of protons and neutrons in an atom.

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Atomic Mass Unit

Back 9

The approximate mass of a proton or neutron; also called a dalton.

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Orbital

Back 10

Region in which electrons occur in an atom or molecule.

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Electron Shell

Back 11

Group of orbitals of electrons with similar energies.

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Principal Energy Levels

Back 12

Electrons in orbitals with similar energies.

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Valence Electrons

Back 13

The electrons in the outer electron shell.

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Chemical Compound

Back 14

Atoms of two or more elements combined in a fixed ratio.

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Molecule

Back 15

Two or more atoms strongly joined to form a stable particle.

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Chemical Formula

Back 16

A representation of the composition of a compound. The elements are indicated by their chemical symbols with subscripts to indicate their ratios.

Front 17

Simplest Formula

Back 17

A type of chemical formula that gives the smallest whole-number ratio of the component atoms.

Front 18

Molecular Formula

Back 18

The type of chemical formula that gives the actual numbers of each type of atom in a molecule.

Front 19

Structural Formula

Back 19

A type of chemical formula that shows the spatial arrangement of of the atoms in a molecule.

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Mole

Back 20

The atomic mass of an element or the molecular mass of a compound expressed in grams.

Front 21

Avogardo's Number

Back 21

The number of units present in one mole of any substance. (6.02 x 10^23)

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Covalent Bond

Back 22

The chemical bond involving shared pairs of electrons; may be single, double, or triple.

Front 23

Orbital Hybridization

Back 23

The process by whic the orbitals of valence electrons become rearranged.

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Non-polar

Back 24

Chemical bond formed by the equal sharing of electrons between atoms of approximate equal electronegativities.

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Polar

Back 25

Chemical bond formed by the sharing of electrons bewteen atoms that differ in electronegativity.

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Electronegativity

Back 26

A measure of an atom's attraction for electrons.

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Ionic Bond

Back 27

The chemical attraction between a cation and an anion.

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Cation

Back 28

A particle with one or more units of positive charge.

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Anion

Back 29

A particle with one or more units of negative charge.

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Hydrogen Bond

Back 30

A weak attractive force existing between a hydrogen atom with a partial positive charge and an electronegative atom with a partial negative charge.

Front 31

Van de Waals interaction

Back 31

Weak attractive forces between atoms that is caused by interactions among fluctuating charges.

Front 32

Autoradiography

Back 32

Method for detecting radioactive decay. The radiation causes the appearance of dark silver grains in special X-ray film.

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Radioisotopes

Back 33

Unstable isotopes tha spontaneously emit radiation.

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Isotope

Back 34

An alternative form of an element with a different number of neutrons but the same number of protons and electrons.

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Oxidation

Back 35

The loss of one or more electrons by an atom, ion, or molecule.

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Molecular Mass

Back 36

The sum of the atomic masses of the atoms that make up a molecule of a compound.

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Reactant

Back 37

Substance that participates in a chemical reaction.

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Product

Back 38

Substance formed by a chemical reaction.

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Dynamic Equilibrium

Back 39

The condition of a chemical reaction when the rate of change in one direction is exactly the same as the rate of change in the opposite direction.

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Reduction

Back 40

The gain of one or more electrons by an atom, ion, or molecule.

Front 41

Redox Reactions

Back 41

The chemical reaction in which one or more electrons are transferred from one substance to another.

Front 42

Polar Molecule

Back 42

Molecule that has one end with a partial positive charge and the other with a partial negative charge. These are generally soluble in water.

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Solvent

Back 43

Substance capable of dissolving other substances.

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Solute

Back 44

A dissolved substance.

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Cohesion

Back 45

The property of sticking together.

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Adhesion

Back 46

The property of sticking to another substance.

Front 47

Specific Heat

Back 47

The amount of heat energy needed to raise the temperature 1 gram of a substance 1 degree C.

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Heat of Vaporization

Back 48

The amount of heat energy that must be supplied to change one gram of substance from the liquid phase to the vapor phase.

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Evaporative Cooling

Back 49

Process in which faster moving molecules when water is heated escape the liquid phase and enter the vapor phase.

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Acid

Back 50

A substance that is a hydrogen ion (proton) donor; acids unite with bases to form salts.

Front 51

Base

Back 51

A substance that is a hydrogen ion (proton) acceptor;bases unite with acids to form salts.

Front 52

pH

Back 52

The negative logarithm of the hydrogen ion concentration of a solution (expressed as moles per liter). Neutral pH is 7, values less than 7 are acidic, and those greater than 7 are basic.

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Neutral Solution

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A solution of pH is 7; there are equal concentrations of hydrogen ions [H+] and hydroxide ions [OH-].

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Buffer

Back 54

A substance in a solution that tends to lessen the change in hydrogen ion concentration (pH) that otherwise would be produced by adding an acid or base.

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Salt

Back 55

An ionic compound consisting of an anion other than a hydroxide ion and a cation other than a hydrogen ion.

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Electrolyte

Back 56

A substance that dissociates into ions when dissolved in water; the resulting solution can conduct an electric current.

Front 57

Nonelectrolytes

Back 57

Substances such as sugars and alcohols that do not form ions when dissolved in water and they do not conduct an electric current.

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Surface Tension

Back 58

The attraction that the molecules at the surface of a liquid may have for one another.

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Capillary Action

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The ability of water to move in small-diameter tubes as a consequence of its cohesive and adhesive properties.

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Hydrophilic

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Interacting readily with water; having a greater affinity for water molecules than they have for each other.

Front 61

Hydrophobic

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Not readily interacting with water; having less affinity for water molecules than they have for each other.

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Kinetic Energy

Back 62

Energy of motion.

Front 63

Heat

Back 63

The total amount of kinetic energy in a sample of a substance.

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Temperature

Back 64

The average kinetic energy of the particles in a sample of a substance.

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Hydration

Back 65

Process of association of a substance with the partial positive and/or negative charges of water molecules.

Front 66

Periodic Table

Back 66

A chart of the elements arranged in order by atomic number.

Front 67

Electron Configuration

Back 67

The arrangement of electrons around the atom.