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

Johannes Diderik van der Waals

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