Ch. 2 - Atomic Structure and Interatomic Bonding

Question 1

Atomic number (Z)

Answer 1

Number of protons in the nucleus.

Question 2

Isotope

Answer 2

Atoms of the same element with a different number of neutrons, and therefore a different atomic masses.

Question 3

Atomic weight

Answer 3

Weighted average of the atomic masses of an atom’s naturally occurring isotopes.

Question 4

Atomic mass unit (amu)

Answer 4

Defined as 1/12 of the atomic mass of the most common isotope of carbon, carbon 12. Can be used in calculations of atomic weight.

Question 5

Mole

Answer 5

6.023e23 atoms or molecules in one ____ of a substance.

Question 6

Quantum mechanics

Answer 6

A set of principles and laws that govern systems of atomic and subatomic entities.

Question 7

Bohr Atomic Model

Answer 7

Electrons are assumed to revolve around the atomic nucleus in discrete orbitals and the position of any particular electron is more or less well defined in terms of its orbital.

Question 8

Wave mechanical model

Answer 8

The electron is considered to exhibit both wave-like and particle-like characteristics. The electron is no longer a particle moving in discrete orbital, rather position is considered to be the probability of an electron being at various locations around the nucleus. Electron cloud.
Replaced Bohr model.

Question 9

Quantum numbers

Answer 9

Used to characterize every electron in an atom.

Question 10

Principal quantum

Answer 10

n = 1, 2, 3, 4, 5…

Related to the distance of an electron from the nucleus, or its position.

Question 11

Second quantum number

Answer 11

l = s, p, d, f

Related to the shape of the electron subshell.

Question 12

Third quantum number

Answer 12

mL
Determines the number of energy states for each subshell.
For s, there is a single energy state. For p, there are 3 energy states. For d, there are five. For f, there are seven.

Question 13

Fourth quantum number

Answer 13

mS

Spin moment associated with each electron. Must be oriented either up or down. +1/2 or -1/2

Question 14

Electron states

Answer 14

Values of energy that are permitted for electrons.

Question 15

Pauli exclusion principle

Answer 15

Each electron state can hold no more than two electrons, and they must have opposite spins. The s subshell can hold 2 electrons, p can hold 6, d can hold 10, and f can hold 14. Electrons fill up the lowest possible energy states in the electron shells and subshells, two per state.

Question 16

Ground state

Answer 16

When all electrons occupy the lowest possible energies.

Question 17

Electron configuration

Answer 17

Represents the manner in which the energy states of an atom are occupied.

Question 18

Valence electrons

Answer 18

Electrons that occupy the outermost shell. These electrons participate in bonding between atoms to form atomic and molecular aggregates.

Question 19

Stable electron configuration

Answer 19

When the valence electron shell is completely filled. An atom can achieve this state based on its default electron configuration or by gaining or losing electrons to form charged ions, or by sharing electrons with other atoms.

Question 20

Noble gases

Answer 20

Elements with their outermost shell full. They are inert (unreactive).

Question 21

Electropositive

Answer 21

Elements that are capable of giving up their few valence electrons to become positively charged ions. Mostly metals.

Question 22

Electronegative

Answer 22

Atoms situated in the right side of the periodic table will readily accept electrons to form negatively charged ions, or sometimes share electrons with other atoms.

This property increases from left to right and from bottom to top.

Question 23

Bonding forces

Answer 23

The magnitude of the attractive force varies with distance. When the valence shells to two atoms begin to overlap, strong repulsive forces come into play.

Question 24

Bonding energy

Answer 24

A state of equilibrium exists when the centers of the two atoms are separated by ro, which is approximately 0.3nm for most atoms. Once in this position, it will take a lot of energy to separate the atoms or push them closer together. The energy at this point is known as the bonding energy. This is the minimum point in the potential energy curve.

Question 25

Primary bond

Answer 25

Ionic
Covalent
Metallic

Question 26

Ionic bonding

Answer 26

Type of bonding found in compounds composed of both metallic and nonmetallic elements (element in horizontal extremes of table). Metallic atoms easily give up their valence electrons to nonmetallic elements. All atoms then acquire a stable/inert gas configuration. Atoms also become ions (ie gain an electrical charge).

NONDIRECTIONAL

Common in ceramics.

Relatively large bonding energies.

Question 27

Nondirectional

Answer 27

The magnitude of the bond is equal in all directions around an ion.

Question 28

Covalent bonding

Answer 28

Type of bonding in which stable electron configurations are assumed by sharing electrons between adjacent atoms. Two atoms bonded in this way will each contribute at least one electron to the bond. The electrons may be considered to belong to both atoms.

DIRECTIONAL, such that the bond is between specific atoms and may only exist in the direction between one atom and another that participated in electron sharing.

Common in nonmetallic molecules (F2, H2), molecules containing dissimilar atoms (H2O, HNO3), and elemental solids (diamond).

Bonding energies can be strong (diamond) or weak (bismuth).

Polymers typically have this bond.

Question 29

Metallic bonding

Answer 29

Type of bonding found in metals and their alloys. Valence electrons are not bound to any particular atom within the solid, but rather are free to drift throughout the entire metal. “Sea of electrons”. Nonvalence electrons form ion cores. Free electrons act as glue to hold ion codes together.

NONDIRECTIONAL.

Bonding energies can be weak or strong.

Sea of electrons is what gives metals good conductivity.

Question 30

Secondary bonds (van der Waals bonds)

Answer 30

Weak bonds in comparison to primary bonds. Exists between virtually all molecules or atoms. Arises from atomic or molecular dipoles. Bonding results from coulombic attraction between the positive end of one dipole and the negative region of an adjacent one.

Fluctuating induced dipoles
Polar molecule-induced dipole bonds
Permanent dipole bonds

Question 31

Dipole

Answer 31

Exists whenever there is some separation of positive and negative positions of an atom or molecule.

Question 32

Hydrogen bonding (permanent dipole bond)

Answer 32

Special type of secondary bonding, found to exist between some molecules that have hydrogen as one of the constituents. Bonded hydrogen acts as a bare proton. Highly positive and therefore capable of strong attractive forces with the negative end of an adjacent molecule.

This type of bonding is what causes ice to be less dense than water.

Question 33

Induced dipole bonds

Answer 33

A dipole can produce a displacement of the electron distribution of an adjacent molecule or atom, which indices the second one also to become a dipole that is then weakly attracted or bonded to the first.
Type of van der Waals bonding.

Question 34

Polar molecule-induced dipole bonding

Answer 34

A polar molecule is a molecule with a permanent dipole moment that exists by virtue of an asymmetrical arrangement of positively and negatively charged regions.

This type of molecule can induce dipoles in adjacent nonpolar molecules and a bind will form as a result of the attractive forces between the two molecules. This bond is stronger than those in fluctuating induced dipoles.