Chromatography, Kinetic Energy and Lewis Dot now with water!

#isomers

With repulsion, a lone pair of electrons…

has a greater repulsion ability than a bonding pair.

What type of substances do Lewis Dot work with?

Covalent Molecular ONLY

What is a Linear shape?

Molecules with only two or three areas of bonding pairs of electrons around the central atom.

What is a Bent/V-Shape?

Four pairs of electrons around a central atom BUT only two lone pairs OR Three pairs with one lone pair.

What is a Trigonal Planar shape?

Three bonding pairs of electrons around central atom with no lone pairs.

What is a Pyramidal shape?

Three pairs of electrons around the central atom with a lone pair of electrons

What is a Tetrahedral shape?

Four bonding pairs of electrons around the central atom.

What is a Polar bond?

A bond formed between atoms of differing electronegativity, meaning that the electrons are not evenly shared between the nuclei but are attraccted to the more electronegative element to a greater degree.

What does a polar bond result in?

A positive ‘end‘ and a negative ‘end‘ or positive and negative dipoles.

Can a non-polar molecule have a polar bond?

Yes

How can you tell how polar a molecule is?

The greater the difference in the electronegativity of the atoms involved in the bond, the more polar the bond and therefore the more polar the molecule

What atoms are the exception that all electrons require 8 electrons? Name and give amount they need.

Hydrogen = 2

Beryllium = 4

Boron = 6

What are the three types of intermolecular forces?

Dispersion, Dipole-Dipole, Hydrogen bonding

What are dispersion forces?

Weakest kind of intermolecular force that exists between the particles of ALL molecules.

What are dipole-dipole forces?

Weak attractive forces that occue between two polar molecules.

What are hydrogen bonding bonds?

Special case of dipole-dipole forces, occurs when a hydrogen atom is bonded with either Fluorine, Oxygen or Nitrogen.

The strength of combined intermolecular forces determines…

the melting and boiling points of covalent molecular substances.

Is the melting and boiling point of dispersion forces low, medium or high?

Lowest melting and boiling points

Is the melting and boiling point of dipole dipole forces low, medium or high?

Medium melting and boiling points

Is the melting and boiling point of hydrogen bonding forces low, medium or high?

High melting and boiling points

If two molecules have the same type(s) of intermolecular forces, how can you tell which has the higher melting and boiling point?

The size of the molecular mass or the shape of the molecule which allows greater contact.

Generally, polar substances will be…

soluble in polar solvents.

Generally, non polar substances will be…

soluble in non polar solvents.

What things can affect solubility?

Stronger the force, the better the solubility

Size of the molecule, bigger = decrease in solubility

Shape can affect solubility

What is the full formula for density?

density = mass / volume

As the temperature of water decreases, what happens?

The volume increases and it becomes less dense.

Why does ice float on water?

Because it is less dense than liquid water

When does ice have low density?

Between 0 and 4 celcius due to the changes in hydrogen bonds

What happens when water turns to ice?

The molecules move less and the forces are more stable. The arrangement of the molecules in a hexagonal shape which takes up more volume and decreases the density.