Chapter 2 The Chemical Context

Question 0

Element

Answer 0

Any substance that cannot be broken down to any other substance by chemical reactions

Question 1

Matter

Answer 1

Anything that takes up space and has mass

Question 2

Compound

Answer 2

A substance consisting of two or more different elements combined in a fixed ratio

Question 3

Essential Element

Answer 3

A chemical element required for an organism to survive, grow, and reproduce

Question 4

Trace Element

Answer 4

An element indispensable for life but required in extremely minute amounts

Question 5

Atom

Answer 5

The smallest unit of matter that refrains the properties of an element

Question 6

Neutron

Answer 6

A subatomic particle having no electrical charge (electrically neutral), with a mass of about 1.7 X 10*-24g, found in the nucleus of an atom

Question 7

Proton

Answer 7

A subatomic particle with a single positive electrical charge, with a mass of about 1.7 X 10*-24g, found in the nucleus of an atom

Question 8

Electron

Answer 8

A subatomic particle with a single negative electrical charge and a mass about 1/2,000 that os a neutron or proton. One or more electrons move around the nucleus of an atom

Question 9

Atomic Nucleus

Answer 9

An atom’s dense central core, containing protons and neutrons

Question 10

Dalton

Answer 10

A measure of mass for atoms and subatomic particles; the same as the atomic mass unit, or amu

Question 11

Atomic Number

Answer 11

The number of protons in the nucleus of an atom, unique for each element and designated by a subscript

Question 12

Mass Number

Answer 12

The sum of the number of protons and neutrons in an atom’s nucleus

Question 13

Atomic Mass

Answer 13

The total mass of an atom, numerically equivalent to the mass in grams of 1 mole of the atom

Question 14

Isotope

Answer 14

One of several atomic forms of an element, each with the same number of protons but a different number of neutrons, thus differing in atomic mass

Question 15

Radioactive Isotope

Answer 15

An isotope (an atomic form of a chemical element) that is unstable; the nucleus decays spontaneously, giving off detectable particles and energy

Question 16

Half-life

Answer 16

The amount of time it takes for 50% of a sample of a radioactive isotope to decay

Question 17

Radiometric Dating

Answer 17

A method for determining the absolute age of rocks and fossils, based on the half-life of radioactive isotopes

Question 18

Energy

Answer 18

The capacity to cause change, especially to do work (to move matter against an opposing force)

Question 19

Potential Energy

Answer 19

The energy that matter possesses as a result of its location or spatial arrangement

Question 20

Electron Shell

Answer 20

An energy level of electrons at a characteristic average distance from the nucleus of an atom

Question 21

Valence Electron

Answer 21

An electron in the outermost electron shell

Question 22

Valence Shell

Answer 22

The outermost energy shall of an atom, containing the valence electrons involved in the chemical reactions of that atom

Question 23

Orbital

Answer 23

The three-dimensional space where an electron is found 90% of the time

Question 24

Chemical Bond

Answer 24

An attraction between two atoms, resulting from a sharing of outer-shell electrons or the presence of opposite charges on the atoms. The bonded atoms gain complete outer electron shells

Question 25

Molecule

Answer 25

Two or more atoms held together by covalent bonds

Question 26

Single Bond

Answer 26

A single covalent bond; the sharing of a pair of valence electrons by two atoms

Question 27

Double Bond

Answer 27

A double covalent bond; the sharing of two pairs of valence electrons by two atoms

Question 28

Valence

Answer 28

The bonding capacity of a given atom; usually equals the number of unpaired electrons required to complete the atom's outer-most (valence) shell

Question 29

Electronegativity

Answer 29

The attraction of a given atom for the electrons of a covalent bond

Question 30

Nonpolar Covalent Bond

Answer 30

A type of covalent bond in which electrons are share equally between two atoms of similar electronegativity

Question 31

Polar Covalent Bond

Answer 31

A covalent bond between atoms tat differ in electronegativity. The shared electrons are pulled closer to the more electronegative atom, making it slightly negative and the other atom slightly positive

Question 32

Ion

Answer 32

An atom or group of atoms that has gained or lost one or more electrons, thus acquiring a charge

Question 33

Cation

Answer 33

A positively charged ion

Question 34

Anion

Answer 34

A negatively charged ion

Question 35

Ionic Bond

Answer 35

A chemical bond resulting from the attraction between oppositely charged ions

Question 36

Ionic Compound

Answer 36

A compound resulting from the attraction between oppositely charged ions

Question 37

Hydrogen Bond

Answer 37

A type of weak chemical bond that is formed when the slightly positive hydrogen atom of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule or in another region of the same molecule

Question 38

Van der Waals interactions

Answer 38

Weak attractions between molecules or parts of molecules that result from transient local partial charges

Question 39

Chemical Reaction

Answer 39

The making and breaking of chemical bonds, leading to changes in the composition of matter

Question 40

Reactant

Answer 40

A starting material in a chemical reaction

Question 41

Product

Answer 41

A material resulting from a chemical reaction

Question 42

Chemical Equilibrium

Answer 42

In a chemical reaction, the state in which the rate of the forward reaction equals the rate of the reverse reaction, so that the relative concentrations of the reactants and products do not change with time