Unit 1 - Structure and Properties of Matter

Question 1

Electromagnetic radiation

Answer 1

Radiant energy that exhibits wavelike behavior and travels through space at the speed of light in a vacuum.

Question 2

Wavelength

Answer 2

The distance between two consecutive peaks of troughs in a wave.

Question 3

Frequency

Answer 3

The number of waves (cycles) per second that pass a given point in space.

Question 4

Planck’s constant

Answer 4

The constant relating the change in energy for a system to the frequency of the electromagnetic radiation absorbed or emitted; equal to 6.626 x 10^-34 Js.

Question 5

Quantization

Answer 5

The concept that energy can occur only in discrete units called quanta.

Question 6

Ground state

Answer 6

The lowest possible energy state of an atom or molecule.

Question 7

Dual nature of light

Answer 7

The statement that light exhibits both wave and particulate properties.

Question 8

Diffraction

Answer 8

The scattering of light from a regular array of points or lines, producing constructive and destructive interference.

Question 9

Continuous spectrum

Answer 9

A spectrum that exhibits all the wavelengths of visible light.

Question 10

Line spectrum

Answer 10

A spectrum showing only certain discrete wavelengths.

Question 11

Standing wave

Answer 11

A stationary wave as on a string of a musical instrument; in the wave mechanical model, the electron in the hydrogen atom is considered to be a standing wave.

Question 12

Wave function

Answer 12

A function of the coordinates of an electron;s position in 3D space that describes the properties of the electron.

Question 13

Orbital

Answer 13

A specific wave function for an electron in an atom. The square of this function gives the probability distribution for the electron.

Question 14

Heisenberg uncertainty principle

Answer 14

A principle stating that there is a fundamental limitation to how precisely both the position and momentum of a particle can be known at a given time.

Question 15

Probability distribution

Answer 15

The square of the wave function indicating the probability of finding an electron at a particular point in space.

Question 16

Principal quantum numbers (n)

Answer 16

The quantum number relating to the size and energy of an orbital; it can have any positive integer value.

Question 17

Angular momentum number (l)

Answer 17

The quantum number relating to the shape of an atomic orbital, which can assume any integral value from 0 to n-1 for each value of n.

Question 18

Magnetic quantum number (ml)

Answer 18

The quantum number relating to the orientation of an orbital in space relative to the other orbitals with the same l quantum number. It can have integral values between l and -l, including zero.

Question 19

Subshell

Answer 19

A set of orbitals with a given azimuthal quantum number.

Question 20

Node

Answer 20

An area of an orbital having zero electron probability.

Question 21

Degenerate orbitals

Answer 21

A group of orbitals with the same energy.

Question 22

Electron spin quantum number (ms)

Answer 22

A quantum number representing one of the two possible values for the electron spin; either +1/2 or -1/2.

Question 23

Pauli exclusion principle

Answer 23

In a given atom no two electrons can have the same set of four quantum numbers.

Question 24

Ionization energy

Answer 24

The minimum energy required to remove the most loosely held electron from an atom or an ion at its gaseous, ground state.

Question 25

Electron affinity

Answer 25

The energy change associated with the addition of an electron to a gaseous atom.

Question 26

Bond energy

Answer 26

The energy required to break a given chemical bond.

Question 27

Ionic bonding

Answer 27

The electrostatic attraction between oppositely charged ions.

Question 28

Ionic compound

Answer 28

A compound that results when a metal reacts with a nonmetal to form a cation and an anion.

Question 29

Coulomb’s law

Answer 29

E = 2.31 x 10^-19 * [(Q1Q2)/r], where E is the energy of interaction between a pair of ions, expressed in joules; r is the distance between the ion centers in nm; and Q1 and Q2 are the numerical ion charges.

Question 30

Bond length

Answer 30

The distance between the nuclei of the two atoms connected by a bond; the distance where the total energy of a diatomic molecule is minimal.

Question 31

Covalent bonding

Answer 31

A type of bonding in which electrons are shared by atoms.

Question 32

Polar covalent bonding

Answer 32

A covalent bond in which the electrons are not shared equally because one atom attracts them more strongly than the other.

Question 33

Electronegativity

Answer 33

The tendency of an atom in a molecule to attract shared electrons to itself.

Question 34

Dipole moment

Answer 34

A property of a molecule whose charge distribution can be represented by a center of positive charge and a center of negative charge.

Question 35

Isoelectronic ions

Answer 35

Ions containing the same number of electrons.

Question 36

Lattice energy

Answer 36

The energy change occurring when separated gaseous ions are packed together to form an ionic solid.

Question 37

Localized electron (LE) model

Answer 37

A model that assumes that a molecule is composed of atoms that are bound together by sharing pairs of electrons using the atomic orbitals of the bound atoms.

Question 38

Valence shell electron-pair repulsion (VESPR) model

Answer 38

A model whose main postulate is that the structure around a given atom in a molecule is determined principal by minimizing electron-pair repulsions.

Question 39

Hybridization

Answer 39

A mixing of the native orbitals on a given atom to form special atomic orbitals for bonding.

Question 40

Hybrid orbitals

Answer 40

A set of atomic orbitals adopted by an atom in a molecule different from those of the atom in the free state.

Question 41

Condensed states of matter

Answer 41

Liquids and solids.

Question 42

Intermolecular forces

Answer 42

Relatively weak interactions that occur between molecules.

Question 43

Dipole-dipole attraction

Answer 43

The attractive force resulting when polar molecules line up so that the positive and negative ends are close to each other.

Question 44

Hydrogen bonding

Answer 44

Unusually strong dipole-dipole attractions that occur among molecules in which hydrogen is bonded to a highly electronegative atom.

Question 45

London dispersion forces

Answer 45

The forces, existing among noble gas atoms and nonpolar molecules, that involve an accidental dipole that induces a momentary dipole in a neighbor.

Question 46

Aufbau principle

Answer 46

The principle stating that as protons are added one by one to the nucleus to build up the elements, electrons are similarly added to hydrogen-like orbitals.

Question 47

Hund’s rule

Answer 47

The lowest energy configuration for an atom is the one having the maximum number of unpaired electrons allowed by the Pauli exclusion principle in a particular set of degenerate orbitals, with all unpaired electrons having parallel spins.

Question 48

Intramolecular forces

Answer 48

The forces of attraction which hold an individual molecule together (for example, the covalent bonds) are known as intramolecular attractions.