Chemical Bonding and Molecular Properties

• Atoms are made of subatomic particles and are the simplest unit of an element.
• Molecules consist of 2 or more atoms combined.
• Compounds consist of 2 or more elements combined.
• Electron arrangement dictates how electrons fill orbitals, with the first shell holding 2 electrons and subsequent shells holding 8, 8, 18 electrons.
• Valence electrons are located in the outermost orbital and form bonds with other atoms.

Intramolecular Bonds

• Covalent bonds involve sharing valence electrons between non-metals and are common in organic molecules.
• Polar covalent bonds involve unequal sharing of valence electrons, resulting in partial charges (δ+ and δ-).
• Ionic bonds involve the transfer of electrons between a metal and a non-metal.

Polarity

• Polar bonds occur when the electronegativity difference between two elements is >0.5, creating partial positive and negative charges.
• Examples of molecules with polar bonds : carbon monoxide, water, ammonia, and cyanide.
• Non-polar bonds occur between the same element.

Lone Pair of Electrons

• Contribute to net charges, causing partial negativity.
• Molecules with both lone pairs and asymmetry are polar.
• A molecule with polar bonds can be non-polar if the polar bonds are symmetrical, canceling each other out.

Polarity and Properties

• Non-polar molecules tend not to attract one another, are not aqueous (hydrophobic), and have low melting/boiling points.
• Polar molecules attract one another, are aqueous (hydrophilic), and have higher melting/boiling points.

Isotopes

• Isotopes: Different forms of an element with varying masses due to differing numbers of neutrons.

Ions

• Ion: An element with a charge.
• Cation: Positively charged ion.
• Anion: Negatively charged ion.

Charge on Atoms

• Charge on atoms is determined by the number of electrons removed (+) or added (-), aiming to fill the outer valence shell for stability.
• Electron: Orbiting the nucleus with a charge of -1 and negligible mass (0 amu).
• Neutron: Located in the nucleus with a charge of 0 and a mass of 1 amu.
• Proton: Located in the nucleus with a charge of +1 and a mass of 1 amu.

Compounds

• Atoms combine to form compounds for increased stability, which are either ionic or covalent.
• Covalent compounds share electrons and consist of two non-metals.
• Ionic compounds involve electron transfer from one atom to another and consist of a metal and non-metal.
• Ions are held together by electrostatic attraction in an aqueous environment.

Carbon

• Carbon forms a variety of structures due to its four valence electrons.
• There are 92 natural elements, with 25 essential for life and 6 fundamental elements making up 98% of living things.
• The 6 fundamental elements are oxygen, carbon, hydrogen, phosphorus, nitrogen, and sulfur.
• These elements form 1, 4, 1, 3, 3, and 2 bonds, respectively.

Water

• All life is water-based, with living organisms being approximately 75% water.
• Water has slight charges, with oxygen being more negative and hydrogen more positive, causing it to be polar.
• Water molecules form hydrogen bonds with other polar molecules.

Intermolecular vs Intramolecular Bonds

• Intermolecular bonds are bonds between molecules, which can include hydrogen bonding, hydrophobic, and hydrophilic interactions.
• Intramolecular bonds are bonds within a molecule and can be covalent or ionic.

Solubility & Polarity

• "Like dissolves like," meaning polar molecules dissolve in polar solvents like water, while non-polar molecules dissolve in non-polar solvents.
• Hydrophilic substances like water and polar molecules, whereas hydrophobic substances do not dissolve in water and are non-polar.

Properties of Water

• Water has 6 key properties: adhesion and cohesion, lower density as a solid compared to liquid, high specific heat capacity, high heat of vaporization/fusion, good solvent capabilities, and ionization.
• Its molecular formula is H2O.
• Ice is less dense than liquid water
• Water molecules can form up to 4 hydrogen bonds.
• Has a very high specific heat capacity

Adhesion & Cohesion

• Cohesion is the clinging of a substance to itself.
• Adhesion is the clinging of one substance to another.
• Adhesion and cohesion aid in capillary action in plants, allowing water to be drawn up the xylem.

Surface tension

• Surface tension is the measure of how difficult it is to break the surface of a liquid.
• Water is most dense at 4°C.

Specific Heat Capacity

• Specific heat capacity is the amount of energy needed to heat 1 g of a substance by 1°C.
• Water's high specific heat capacity allows aquatic life to survive even when the atmospheric temperature drops.

Heat of Vaporization

• Is the amount of energy needed to change heat from liquid to gas.
• Sweating cools us down as water evaporates, drawing heat from the body

Heat of Fusion

• Heat of fusion is a lot of energy is needed to change ice from solid to liquid.

Solubility

• Solubility: Water is a versatile solvent due to its polarity by dissolving into polar regions.
• Ionization of water helps mitochondria produce ATP (energy) and maintain the body's pH balance.

Functional Groups

• Hydrocarbons contain carbon and hydrogen.
• Saturated: Hydrocarbons with single bonds only.
• Unsaturated: Hydrocarbons with double or triple bonds.
• A functional group is a group of atoms attached to a carbon skeleton, typically involved in chemical reactions.

Hydroxyl Group (-OH)

• Polar, helps dissolve organic compounds, enables hydrogen bonding.

Carbonyl Group (C=O)

• If carbonyl group is at the end of the carbon chain = Aldehyde
• If carbonyl group is in the middle of the carbon chain = Ketone

Carboxyl Group (-COOH)

• Polar tendencies, engages in H-bonding, and has the potential to dissociate, giving shares and taking away from (electronegativity differences).

Amino Group (-NH2)

• Important in proteins, enables H-bonding.

Sulfhydryl Group (-SH)

• Helps stabilize the protein structures of structures.

Phosphate Group (-OPO3^2-)

• Very polar due to high electronegativity of oxygen, enables H-bonding, and is found in ATP and DNA.

Ether Linkage

• Ether linkage forms from condensation.

Ester Linkage

• Forms from the condensation of an alcohol and carboxylic

Condensation Reactions & Hydrolysis

• Condensation reactions: Subunits merge together into one large molecules by removing water.
• Hydrolysis reactions: One large molecule can be broken into two subunits by adding water.

Carbohydrates

• Are sugars and contain carbon, hydrogen, and oxygen in a 1:2:1 ratio.
• Made of monosaccharides joined together in long chains = Polysaccharides
• All of life converts the majority of its organic components in their bodies to sugars.

Glucose (C6H12O6)

• Glucose is the basic sugar produced by plants through photosynthesis
• Glucose - primary energy source for cell respication.
• A simple sugar, or monosaccharide
• It is most often found when complex chains break down into glucose
• It has two types: alpha (α) and beta (β), with the difference being the location of the OH group.

Fructose (C6H12O6)

• Common sugar found in fruits and honey
• Has the same formula as glucose, but a different structure hence it is an isomer of glucose

Galactose

• Identifies human blood types
• Blood types A and B differ due to one monosaccharide - "A" contains N-acetyl galactosamine, whereas "B" contains galactose.

Sucrose

• Made from glucose and fructose
• How plants transport sugar

Monosaccharides to Disaccharides

• 2 monosaccharides form - a disaccharide
• It needs to be connected via condensation reaction (Water must is removed)

Glycosidic Linkages

• Glycosidic linkages links the 2 molecules
  • maltose = glucose + glucose
  • lactose = galactose + glucose
  • sucrose = glucose + fructose

Polymers

• The monosaccharide chains linked in long strands are also known as polysaccharides. _Common in plants, are very recorrent
  • Starches are made by the use of alpha Glucose
• Most starches don't dissolve in water and plants use these long chains for storage.
• The Two are amylose and amylopectin
  • Amylose - Is a straight chain of 1→4 bonded glucose that forms chains. Creates 1,6 bonds causing it to create branches causing it to create branches.
  • This is better because these branches leave more "Ends" than amylose - making it easier to break down.

Glycogen

• Animal starch is the glucose is that is stored for their bodies.
• Forms strong chains and branches

Hydrolysis

• Reverse of condensation (water is needed) Water will breakthe glycosidic link bonds for glucose . Can occurs in polymers and disaccharides

Cellulose

• Plants build strong branches called cellulose. This helps retain the plants structure and water.
• Most of it forms straight chains
• The first chain lines up and bonds by H = cells → OH for plants