Lab 2 Review

Molecular Models

Atoms

The basic units of matter and determine the chemical properties of elements

Molecules

Formed when atoms bond together

• a chemical structure made of two or more atoms held together by covalent or ionic bonds

Compounds

A molecule made from two or more different elements joined in a specific ratio

Compounds vs. Molecules

A molecule is any two or more atoms bonded together (like O₂ or H₂O). A compound must contain at least two different elements. Therefore, all compounds are molecules, but not all molecules are compounds

Carbon

Important in biology because It can form many stables bonds, allowing living organisms to build complex molecules.

Organic compounds

Molecules that contain carbon

• A chemical molecule that contains carbon atoms covalently bonded to hydrogen atoms

Inorganic compounds

Molecules without carbon

• chemical substances that generally lack carbon-hydrogen (C-H) bonds

• Ex; although CO₂ contains a carbon atom, it lacks a carbon-hydrogen bond, thus being inorganic

Functional groups

Specific groups of atoms attached to carbon skeletons that give organic molecules their unique chemical properties, shapes, and reactivities

• They affect how the moleule behaves

Hydroxyl group

A functional group with the formula -OH, consisting of a hydrogen atom covalently bonded to an oxygen atom

• Can increase polarity because oxygen has a much higher electronegativity than hydrogen and carbon, pulling shared electrons closer to itself and creating an unequal distribution of charge

Carboxyl group

A specific arrangement of atoms (-COOH) consisting of a carbon atom double-bonded to an oxygen atom and single-bonded to a hydroxyl group (-OH)

• Can act as an acid because it can easily release a hydrogen ion

Amino group

Functional group with the chemical formula (-NH₂) consisting of a single nitrogen atom bonded to two hydrogen atoms

• Can act as a base

Empirical formula

Lists the types and numbers of atoms in a molecule

• Ex; water is written as H₂O because each water molecule contains two hydrogen atoms and one oxygen atom

Structural formula

Shows how atoms in a molecule are arranged and chemically bonded to one another

Shortest sticks

Used for hydrogen atoms

Medium sticks

Used for single covalent bonds

Longest flexible gray sticks

Used for multiple covalent bonds

Amino acid structure

Proteins are built from amino acids. Although there are 20 different amino acids, they all share the same basic structure:

• An amino group (-NH2)

• A carboxyl group (-COOH)

• A central carbon

R group

The unique side chain of each amino acid

• Differences in this group hep determine an amino acid’s polarity, charge, and role in protein folding

“Pentose” sugar

A simple five-carbon monosaccharide that serves as the central structural component of nucleotides in DNA and RNA

Deoxyribose

A five-carbon sugar found in DNA

• Empirical formula: C5H10O4

What is the difference between ribose and deoxyribose?

Ribose has a hydroxyl group (-OH) attached to its second carbon, while deoxyribose has only a hydrogen atom (-H), meaning it has "lost" an oxygen

What does “deoxy” mean

A molecule has less oxygen or has lost an oxygen atom compared to its original or parent compound

• Deoxyribose has one less oxygen than ribose

Dehydration synthesis

Glucose and fructose join to form sucrose, a disaccharide. During this reaction, a hydroxyl group (-OH) is removed from one monosaccharide and a hydrogen atom (H) is removed from the other. These removed groups combine to form water, allowing the two sugars to bond

What does the suffix “ose” indicate?

Indicates that a molecule is a carbohydrate or sugar

• this suffix used to name simple sugars (monosaccharides) like glucose and fructose, as well as double sugars (disaccharides) like sucrose and lactose

What atom does each black ball represent?

Carbon

What atom does each red ball represent?

Oxygen

What atom does each white ball represent?

Hydrogen

What do the shortest bond sticks represent?

• Hydrogen atoms

• Single covalent bonds

Why is Carbon Dioxide nonpolar?

Because its geometric shape is completely linear, causing its individual bond polarities to cancel each other out

Where are peptide bonds found?

Found in proteins (and polypeptides), specifically linking adjacent amino acids together in the primary structure of the protein backbone

What happens during dehydration synthesis, and why is water produced?

During dehydration synthesis, small molecules (monomers) join together to form larger chains (polymers) while releasing a water molecule as a byproduct

Isomers

Molecules that have the same molecular formula (the same number and types of atoms) but different structural arrangements, which gives them unique chemical properties and biological functions

How can two molecules have the same formula but different structures (isomers)?

Because atoms can connect in different orders or arrange themselves differently in three-dimensional space