Unit 4 Scientists, Vocab, & Molecular/covalent compound prefixes

Johannes Diderik van der Waals

* 1837-1923
* Discovered the equation of state for gases and liquids.
* Made the study of temp near absolute zero possible.
* van der Waals forces

Henry Cavendish

* 1731-1810
* discovered “inflamable air” / hydrogen
* discovered density of air
* discovered earth’s mass

Chemical Compound

combo of 2 or more elements chemically combined.

Chemical Bond

* a force that holds 2 or more atoms together.

Ionic Lattice Structure

* a regular repearing arrangement ions have.
* 3D network

Polyatomic Ion

* a group of atoms covalently bonded with an overall charge.
* has endings such as -ate, -ite, and a few others.

Oxidation #

the charge that an atom would have if the compound was composed of ions.

Structural Formula

shows the arrangement of atoms in the molecule of a compound.

Molecular/Covalent Compound

* chemical compounds that take the form of discrete molecules.
* 2 nonmetals with similar electronegativity
* sharing electrons
* 2 parts:
* Prefix + name of nonmetal
* Prefix + name of nonmetal ending with -ide.

Resonance

a way of describing delocalized electrons within certain molecules or polyatomic ions where the bonding cannot be expressed by a single Lewis formula.

Formal Charge

* the difference between the atom’s # of valence e and the # it owns.
* the result of when atoms end with more or fewer than valence e they brought to get octets.
* FC = valence e - nonbinding e - (1/2) bonding e

Expanded Octet

a valence shell count that exceeds 8 e.

Binary Compound

a chemical compound composed of only 2 elements.

(molecular) domain

the number of lone pairs or bond locations around a particular atom in a molecule.

van der Waals forces

the attraction and repulsions between atoms, molecules, and surfaces, as well as other intermolecular forces.

Dipole

a bond or molecule whos ends have opposite charges.

Cohesion

* a measure of how well molecules stick to each other or group together.
* like molecules attract each other

Adhesion

* the tendency of some substances to cling to other substances.
* dif. molecules attract each other.

Chemical Reaction

* a process in which one or more substances, the reactants, are converted to one or more different substances, the products.
* occurs b/c an element is trying to get a full outer shell.
* once a reaction has occured, the products are NOT likely to react again as they already got their full outer shells.

Formula

shorthand expression showing the elements involved in a compound, and how many of each.

Ionic Bond

* bond formed due to the attraction between 2 oppositely charged ions.
* initiated by transfer of electrons.
* from atoms that want to lose e → one that wants to gaine e.
* metal and nonmetal.
* ATTRACTION

3 things abt Ionic Compound Structure

* attraction in all directions.
* forms network of ions
* not just one ion to one ion

Lewis Dot Structure

diagrams that represent the valence electrons of atoms within a molecule.

Signle covalent bond

* involves 1 shared pair of electrons (2e).
* Halogens and Hydrogen

Double covalent bond

* involves 2 shared pairs of electrons (4e)
* Oxygen and Sulfur

Triple covalent bond

* involves 2 shared pairs of electrons (6e).
* Nitrogen and Phosphorus

1

mono-

2

di-

3

tri-

4

tetra-

5

penta-

6

hexa-

7

hepta-

8

octa-

9

nano-

10

deco-

VSEPR Model

a model used to analyze molecular geometry.

* Valence
* Shell
* Electron
* Pair
* Repulsion

Electron domain geometry

The arrangement of electron domains surrounding the central atom of a molecule or ion.

* bonds and lone pairs
* Ex:
* linear
* trigonal planar
* tetrahedral
* trigonal bipyramidal
* octahedral

Molecular geometry

the three-dimensional arrangement of the atoms that constitute a molecule.

* only bonds

Intermolecular forces

* electrostatic interactions between molecules.


* weaker than intramolecular forces.
* 3 types:
* london dispersion force
* dipole-dipole force
* hydrogen bond

London disperion forces

* weakest
* a temporary attractive force that results when the electrons in two adjacent atoms occupy positions that make the atoms form temporary dipoles.
* between 2 nonpolar compounds

Nonpolar

electrons evenly distributed

Polar

random motion of unevenly distributed electrons

Polarizability

a measure of how easily an electron cloud is distorted by an electric field.

Dipole-dipole forces

* medium strength
* attractive forces between the positive end of one polar molecule and the negative end of another polar molecule.
* one part is always +, the other is always -
* between 2 polar compounds

Hydrogen Bond forces

* a special type of dipole-dipole attraction between molecules, not a covalent bond to a hydrogen atom.


* It results from the attractive force between a hydrogen atom covalently bonded to a very electronegative atom such as a N, O, or F atom and another very electronegative atom.

(molecular) polarity

when an entire molecule, which can be made out of several covalent bonds, has a net polarity, with one end having a higher concentration of negative charge and another end having a surplus of positive charge.

Metallic bond

* a type of chemical bonding that arises from the electrostatic attractive force between conduction electrons (in the form of an electron cloud of delocalized electrons) and positively charged metal ions.
* two metals

Covalent bond

* consists of the mutual sharing of one or more pairs of electrons between two atoms.
* two nonmetals