Comprehensive Study Notes: Atomic Structure, Bonding, Water, and Organic Chemistry

Protons

Positively charged sub-atomic particles located in the nucleus of an atom.

Neutrons

Neutral sub-atomic particles located in the nucleus of an atom.

Electrons

Negatively charged sub-atomic particles found in orbitals surrounding the nucleus.

Elements

Pure substances that contain only one type of atom.

Isotopes

Alternative forms of an element with the same number of protons but different numbers of neutrons.

Radioactivity

The gradual disintegration of unstable atoms, releasing sub-atomic particles and energy.

Valence electron shell

The outermost electron shell of an atom, which determines its reactivity.

Covalent bond

A chemical bond formed by the sharing of one or more pairs of electrons between atoms.

Nonpolar covalent bond

A covalent bond where electrons are shared equally between atoms, resulting in a symmetrical bond.

Polar covalent bond

A covalent bond where electrons are shared unequally because one atom is more electronegative, resulting in an asymmetrical bond.

Electronegativity

A measure of how tightly an atom in a molecule holds electrons.

Ions

Atoms that have gained or lost valence electrons, resulting in a net electrical charge.

Cation

A positively charged ion, formed when an atom loses one or more electrons.

Anion

A negatively charged ion, formed when an atom gains one or more electrons.

Ionic bonds

Atoms

Composed of sub-atomic particles: protons (positively charged), neutrons (neutral), and electrons (negatively charged).

Protons

Positively charged sub-atomic particles located in the nucleus of an atom.

Neutrons

Neutral sub-atomic particles located in the nucleus of an atom.

Electrons

Negatively charged sub-atomic particles found in orbitals surrounding the nucleus of an atom.

Elements

Pure substances that contain only one type of atom.

Isotopes

Alternative forms of an element with the same number of protons but different numbers of neutrons.

Radioactivity

Gradual disintegration of unstable atoms releasing sub-atomic particles and energy.

Chemical Bonding

Interaction between atoms with partly full valence shells to form molecules.

Molecule

Two or more atoms chemically joined by covalent bonds (can be same or different elements).

Compound

Two or more atoms of different elements chemically joined by covalent or ionic bonds.

Covalent Bond

Type of chemical bond where electrons are shared between atoms.

Nonpolar Covalent Bond

Electrons are shared equally between atoms; the bond is symmetrical.

Polar Covalent Bond

Electrons are shared unequally because one atom is more electronegative; the bond is asymmetrical.

Electronegativity

Measure of how tightly an atom in a molecule holds electrons.

Ion

An atom that has gained or lost valence electrons, resulting in a net positive (cation) or negative (anion) charge.

Cation

An ion that loses an electron and becomes positively charged.

Anion

An ion that gains an electron and becomes negatively charged.

Ionic Bond

Forms between oppositely charged ions via electrostatic forces.

Electrolyte

Any substance that is ionized in water and conducts electricity when dissolved.

Solution

A homogeneous mixture.

Solvent

The dissolving agent in a solution.

Solute

The substance that is dissolved in a solvent.

Aqueous Solution

A solution in which water is the solvent.

Hydrogen Bonds

Weak bonds formed between a hydrogen atom of one polar molecule (with a partial positive charge) and a more electronegative atom (with a partial negative charge) of another polar molecule.

Hydrophilic

Substances (ions or polar molecules) that stay in solution due to interactions with water's partial charges, meaning they are 'water-loving'.

Hydrophobic

Mainly nonpolar substances that do not interact well with water, meaning they are 'water-fearing'.

Adhesion

A property of water where it forms hydrogen bonds with other substances (e.g., plastic, cells).

Cohesion

A property of water where water molecules form hydrogen bonds with each other.

Surface Tension

Created by the cohesive forces between water molecules at the water-air interface, causing them to bind more tightly to each other than to air.

Capillary Action

Water moves through narrow spaces due to adhesion to polar surfaces and cohesion among water molecules.

Specific Heat (Water)

A large amount of heat is required to raise the temperature of water by 1 ext{ degree}, contributing to temperature stabilization.

Heat of Vaporization (Water)

A large amount of energy is required to break hydrogen bonds and convert liquid water to vapor, which is crucial for cooling organisms via evaporation.

Dissociation of Water

Water can spontaneously and reversibly dissociate into ext{H}^+ and ext{OH}^- ions, or more accurately, form hydronium ( ext{H}_3 ext{O}^+) and hydroxide ( ext{OH}^-) ions.

Acidic Solutions

Solutions that have more ext{H}^+ (hydrogen ions) than ext{OH}^- (hydroxide ions), characterized by a pH less than 7.

Basic Solutions

Solutions that have more ext{OH}^- (hydroxide ions) than ext{H}^+ (hydrogen ions), characterized by a pH greater than 7.

pH Scale

A logarithmic scale indicating the concentration of hydrogen ions [ ext{H}^+] in a solution, defined as ext{pH} = - ext{log} [ ext{H}^+] . A pH of 7 is neutral.

Organic Compounds

Compounds that contain mostly carbon (e.g., methane, ext{CH}_4).

Inorganic Compounds

Compounds that contain little or no carbon (e.g., water, ext{H}_2 ext{O}).

Functional Groups

Specific groups of atoms attached to a carbon skeleton that influence a molecule's chemical behavior and interactions.

Amino Group

A polar functional group (- ext{NH}_2 or - ext{NH}_3^+ when ionized) that can accept a proton in solution.

Carboxyl Group

A polar functional group (- ext{COOH} or - ext{COO}^- when ionized) that releases a proton in solution.

Carbonyl Group

A polar functional group ( ext{C=O}) that acts as a site to link molecules; can be an aldehyde (at molecule ends) or a ketone (in molecule interior).

Hydroxyl Group

A polar functional group (- ext{OH}) that acts as a weak acid and can donate ext{H}^+ in solution.

Phosphate Group

A polar functional group (- ext{PO}_4^{2-}) with two negative charges when ionized; functions in energy transfer or as part of nucleic acids, also a good buffer.

Sulfhydryl Group

A polar functional group (- ext{SH}) that can link together via covalent disulfide bonds ( ext{S--S}), common