SCI/CHEM
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Chemistry Review · Biology Exam

Chemistry

Interactive reference for every compound, bond type, functional group, and reaction on the exam. Click any atom to explore its role.

3
Bond Types
7
Func. Groups
4
Key Molecules
2
Core Reactions
01 — Bond Types

How atoms connect

The main elements of life are O, C, H, N. The way they bond determines the molecule's properties and behavior.

Covalent

Shared Electrons

Two atoms share a pair of valence electrons. Carbon's 4 valence electrons let it form single, double, or triple covalent bonds — the basis of organic chemistry.

C shared e⁻ C e: 2.5 e: 2.5

Ex: H₂O, CO₂, glucose, organic molecules

Ionic

Electron Transfer

An electron is stripped from one atom, creating a (+) cation and a (–) anion. The electrostatic attraction between the two ions forms the ionic bond.

Na ⁺ e⁻ Cl ⁻

Ex: NaCl — (+) cation · (–) anion attract

Hydrogen

Partial Attraction

Electron pulled slightly toward highly electronegative O or N, exposing the H proton (δ+). This δ+ is attracted to lone pairs on nearby electronegative atoms.

O δ– H δ+ H-bond O ...

Gives H₂O: cohesion · surface tension · high Cₚ

02 — Key Molecules

Interactive structures

Click any highlighted atom or group to open a detailed explanation panel.

Water
H₂O · Amphoteric · Universal Solvent
O δ– H δ+ H δ+ 104.5° bond angle μ dipole

Amphoteric (acts as acid & base) · High specific heat · Ice less dense than liquid (floats) · High cohesion + adhesion → surface tension

Amino Acid
Monomer of proteins · R-group varies across 20 types
Cα H –NH₂ Amino –COOH Carboxyl R-group side chain

Links via peptide bonds (dehydration synthesis). The chain of amino acids folds into 1°→2°→3°→4° protein structures driven by R-group interactions.

Glucose
C₆H₁₂O₆ · Monosaccharide · Primary energy source
Haworth projection · α-D-glucose O C1 C2 C3 C4 C5 –OH –OH –OH –OH CH₂OH α–OH

Links via glycosidic bonds (dehydration) → starch/cellulose. α linkage = starch (digestible). β linkage = cellulose (structural, indigestible).

Nucleotide
Monomer of DNA/RNA · Phosphate + Sugar + N-Base
–OPO₃ ²⁻ Phosphate Pentose deoxyribose/ribose Sugar N-Base A T C G (or U in RNA) 3′ 5′ DNA: deoxyribose · A-T-C-G · double helix (A=T, G≡C) RNA: ribose · A-U-C-G · single strand (A=U, G≡C)

Joined 5′→3′ via phosphodiester bonds (dehydration). DNA: double-stranded antiparallel. A=T (2 H-bonds), G≡C (3 H-bonds, stronger).

3D Model — Water (H₂O) · Three.js
H₂O — drag to rotate · scroll to zoom
three.js r128 · covalent ball-and-stick
03 — Functional Groups

The 7 groups of biology

These groups define chemical behavior of all macromolecules. Click any card to expand a full explanation.

04 — Core Reactions

Building and breaking

Every polymer in biology is built by dehydration synthesis and broken down by hydrolysis. They are inverse reactions.

Photosynthesis vs Cellular Respiration (key biochemical reactions)
6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂  ·  C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP
Dehydration Synthesis
Anabolism · Bond formation · H₂O removed
Monomer A
–OH
+
Monomer B
H–
→
Polymer
–O–
+
H₂O
released
–OH from one monomer reacts with H– from another
→ H₂O is released + covalent bond forms

Examples: Glucose→Starch (glycosidic bond) · Amino acid→Protein (peptide bond) · Nucleotide→DNA (phosphodiester bond)
Hydrolysis
Catabolism · Bond breaking · H₂O added
Polymer
–O–
+
H₂O
added
→
Monomer A
–OH
+
Monomer B
H–
H₂O is added to break the covalent bond
→ polymer split into monomers restored

Examples: Starch→Glucose · Protein→Amino acids · DNA→Nucleotides · Fats→Fatty acids + Glycerol
⚠ Protein Denaturing

When temperature, pH, or chemicals change, the hydrogen bonds holding the 3D protein shape break. The chain unfolds → wrong shape = no function. The primary structure (amino acid sequence) is unchanged — only 2°, 3°, 4° structures are disrupted. Example: boiling an egg (albumin denatures irreversibly).