Molecular interactions and bonding

U1L1

Intramolecular forces

the attraction between atoms

Intermolecular forces

The force between molecules, the force that holds them together.

Determines physical properties (boiling point, melting point, density).

3 main forces: Dipole-dipole, hydrogen bonding, london dispersion forces

Dipole-Dipole forces

only polar molecules since charges are required

opposite charges attract and connect to each other

Hydrogen bonding

applies to compounds with N-H, O-H, H-F

one of the stronger forces

London dispersion forces

weaker forces

includes non-polar molecules

Hydrogen bonding in water

hydrogen atoms of one water molecule are attracted towards oxygen atom of neighboring water molecule. Hydrogen bonds also give water high surface tension dur to their cohesive forces and electrostatic attraction with each other.

ionic compound

tight formed bond by ions (atoms or molecules) of the opposite charge being positive and negative which are usually a metal and nonmetal

positive ions are referred to as?

cation

negative ions are referred to as?

anions

why do ions dissociate and dissolve in water and what does it create

ions have a strong attraction to water molecules and create a hydrated ion when dissociating and dissolving

neutralization reactions

reaction that contains an acid and a base to form water and a salt, involving H+ and OH- ions

heat capacity of water

amount of energy required to raise the temperature of that sample by one degree Celsius

takes 4184 joules of heat to raise temp of 1kg of water to one degree

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density of water as a liquid vs solid

less dense as ice (solid) than as liquid because molecules arrange themselves in a rigid tetrahedral structure in ice, but water molecules remain in linear bonding form

polar molecules

when atoms have significantly different electronegativities and do not share electrons equally

hydrophobic molecules

typically covalent compounds

do not dissolve in water (oil, wax, fats) tend to repel or not absorb water

non-polar

attract other neutral molecules and nonpolar solvents

non-polar molecules

electronegativity difference is less than 0.5

alkynes and noble gases

hydrophilic molecules

ions, alcohols

often charges and capable of hydrogen bonding

dissolve in water more quickly

hydrophilic substances have the ability to draw water out of the air naturally by acting as attractants for it

van der waals forces

forces that attract and repel neutral molecules to and from one another

strength is dependent on size, shape and polarity

caused by correlations in fluctuating polarizations of nearby particles

types of van der waals forces

1. electrostatic

2. induction

3. dispersion

dehydration

when you use up or lose more fluid than you take in

condensation reaction

two molecules combine to form a single molecule with the loss of a small molecule, usually water

AKA dehydration synthesis if water is also lost

used to make crucial large molecules called macromolecules in body such as carbohydrates, lipids and proteins

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hydrolysis reactions

when molecule of water breaks one or more chemical bonds

used for substitution, elimination, solvation reactions

nucleophile

chemical species that forms bonds by donating an electron pair

redox reaction

AKA oxidation-reduction

involves transfer of reactions between 2 species

number of molecule atom or ion changes by gaining or losing electrons

oxidization

loss of electrons

reduction

gain of electrons

isotopes

different forms of the same element

radioisotopes

unstable isotope that decays to release particles