Chem 1220-2 Test Two

Paramagnetism

Electron configurations that result in unpaired electrons mean that the atom or ion will have a net magnetic field

Diamagnetism

Electron configurations that result in all paired electrons mean that the atom or ion will have no magnetic field

Ionization Energy (IE)

The minimum energy needed to remove an electron from an atom or ion in the gas phase

Endothermic Process

Requires the input of energy to remove the electron

Decreases

First ionization energy generally ________ as we move down a column

Increases

First ionization energy generally ________ as we move down a column

General Trend

A trend for the first ionization of main-group elements is that as you go across a period, ionization energy increases

Energy Affinity (EA)

The energy associated with the addition of an electron to the valence shell of an atom that is in the gas phase

Metallic Character

How closely an element’s properties match the ideal properties of a metal

Decreases

Metallic character ______ left to right across a period

Increases

Metallic character _______ down the column

Ionic Bonds

A bond between a metal and a nonmetal that involve the transfer of electrons from one to another

Covalent Bonds

A bond between two or more nonmetals that involve the sharing of electrons between two atoms of high ionization energy

Empirical Formula

Gives the relative number of atoms of each element in a compound (CHO6)

Molecular Formula

gives the actual number of atoms of each element in a molecule of a compound (C6H12O6)

Structural Formula

is a sketch or diagram of how the atoms in the molecule are bonded to each other.

Molecular Model

is a more accurate and complete way to specify a compound

Ball-and-Stick Molecular Model

represents atoms as balls and chemical bonds as sticks; how the two connect reflects a molecule’s shape

Space-Filling Molecular Model

atoms fill the space between each other to more closely represent our best estimates for how a molecule might appear if scaled to visible size

Lews Model

Valence electrons are represented as dots that depict the structural formula

Octet Rule

When atoms bond, they tend to gain, lose, or share electrons to result in a noble gas–like configuration

Period 2

Nonmetal __________ elements must obey the octect rule

Center

Nonmetals (Period 3 on down) follow the octet rule when they are not the ___ atom

Duet

When an electron configuration only contains two valence electrons

Chemical Bond

is the sharing or transfer of electrons to attain a stable electron configuration

Lewis theory

predicts that moving ions out of position should therefore be difficult, and ionic solids should be hard

Crystal Lattice

The extra energy that is released comes from the formation of a structure in which every cation is surrounded by anions and vice versa

Lattice Energy

The extra stability that accompanies the formation of the crystal lattice is measured as the lattice energy

Formula Unit

the basic unit of an ionic compound

Binary Compounds

Contains only two different elements

Oxyanions

Anions containing oxygen and another element

Hydrates

Ionic Compounds containing a specific number of water molecules associated with each formula unit

Hemi

1/2

Mono

1

Di

2

Tri

3

Tetra

4

Penta

5

Hexa

6

Hepta

7

Octa

8

Bonding Pairs

Electrons that are shared by atoms

Lone Pairs (AKA Nonbonding Pairs)

Electrons that are not shared by atoms but belong to a particular atom

Double Covalent Bond

When two atoms share two pairs of electrons

Triple Covalent Bond

When atoms share three pairs of electrons

Lewis Theory

Implies that some combinations should be stable whereas others should not

Empirical Formula Molar Mass

the sum of the masses of all the atoms in the empirical formula

Carbon

The main element that is the focus of organic chemistry is _________.

Molecular Imposter

mimicking the action of endorphins because of similarities in molecular shape

Polar Covalent

When the sharing is unequal enough to produce dipole in the bond

Electronegativity

The ability of an atom to attract electrons to itself in a chemical bond

Pure Covalent

When the difference in electronegativity between bonded atoms is 0

Non-polar Covalent

When the difference in electronegativity between bonded atoms is 0.1 to 0.4

Polar Covalent

When the difference in electronegativity between bonded atoms is 0.5 to 1.9

Ionic

When the difference in electronegativity between bonded atoms is larger than or equal to 2.0

Dipole

A bond or molecule with partial positive and partial negative ends

Percent Ionic Character

The percentage of a bond’s measured dipole moment compared to what it would be if the electrons were completely transferred

Resonance

Used when two or more valid Lewis structures can be drawn for the same compound

Formal Charge

An electron bookkeeping system that allows us to discriminate between alternative Lewis structures

Resonance Structures

When there is more than one Lewis structure for a molecule that differ only in the position of the electrons

Resonance Hybrid

The actual molecule is a combination of the resonance forms

Formal Charge

During bonding, atoms may end up with more or fewer electrons than the valence electrons they brought in order to fulfill octets

Incomplete Octects

molecules or ions with fewer than eight electrons around an atomf

Odd-electron Species

Molecules or ions with an odd number of electrons

Expanded Octects

Molecules or ions with more than eight electrons around an atom

Bond Energy

The amount of energy it takes to break one mole of a bond in a compound in the gaseous state

The more electrons two atoms share, the _________ the bond

stronger

Bond Strength

Measured by how much energy must be added into the bond to break it in half

Bond Length

Determined by measuring the distance between the nuclei of bonded atoms

Electron Groups

Regions of electron density around an atom. These can be lone pairs, single bonds, multiple bonds, and even single electrons.

VSEPR

Electron groups around the central atom will be most stable when they are as far apart as possible

Linear Geometry

When there are two electron groups around the central atom, they will occupy positions on opposite sides of the central atom

Trigonal Planar Geometry

When there are three electron groups around the central atom, they will occupy positions in the shape of a triangle around the central atom

Tetrahedral Geometry

When there are four electron groups around the central atom, they will occupy positions in the shape of a tetrahedron around the central atom

Trigonal Bipyramidal Geometry

When there are five electron groups around the central atom, they will occupy positions in the shape of two tetrahedra that are base-to-base with the central atom in the center of the shared base

Equatorial Positions

The positions in the same base plane as the central atom

Octahedral Geometry

When there are six electron groups around the central atom, they will occupy positions in the shape of two square-base pyramids that are base-to-base with the central atom in the center of the shared bases

Tetrahedral-Bent-Shape

When there are four electron groups around the central atom, and two are lone pairs

Seesaw Shape

When there are five electron groups around the central atom, and one is a lone pair

T-Shaped

When there are five electron groups around the central atom, and two are lone pairs

Linear

When there are five electron groups around the central atom, and three are lone pairs

Square Pyramidal Shape

When there are six electron groups around the central atom, and one is a lone pair

Square Planar Shape

When there are six electron groups around the central atom, and two are lone pairs