4.8 Chemistry Basics
Key Takeaways
- Atoms have protons (+) and neutrons (0) in the nucleus, electrons (-) in shells
- Ionic bonds transfer electrons; covalent bonds share electrons
- pH scale: <7 acid, 7 neutral, >7 base; blood pH is approximately 7.4
- Reaction types include synthesis, decomposition, single/double replacement, and combustion
- Exothermic reactions release energy; endothermic reactions absorb energy
Last updated: January 2026
The TEAS tests fundamental chemistry concepts including atomic structure, chemical bonding, reactions, and solutions. These concepts apply to understanding medications, body chemistry, and laboratory values.
Atomic Structure
| Component | Charge | Location | Mass |
|---|---|---|---|
| Proton | Positive (+) | Nucleus | 1 amu |
| Neutron | Neutral (0) | Nucleus | 1 amu |
| Electron | Negative (-) | Electron shells | ~0 amu |
Key numbers:
- Atomic number = number of protons (defines element)
- Mass number = protons + neutrons
- Atomic mass = weighted average of isotopes
The Periodic Table
| Group | Elements | Properties |
|---|---|---|
| Alkali metals | Li, Na, K | Highly reactive, 1 valence electron |
| Alkaline earth metals | Mg, Ca | Reactive, 2 valence electrons |
| Halogens | F, Cl, Br, I | Very reactive nonmetals, 7 valence electrons |
| Noble gases | He, Ne, Ar | Unreactive, full outer shell (8 electrons) |
Periods: Horizontal rows (indicate electron shells) Groups: Vertical columns (similar properties)
Chemical Bonding
| Bond Type | Description | Example |
|---|---|---|
| Ionic | Transfer of electrons | NaCl (table salt) |
| Covalent | Sharing of electrons | H₂O (water) |
| Hydrogen | Weak attraction between H and O/N/F | Water molecules |
Ionic bonds: Form between metals and nonmetals Covalent bonds: Form between nonmetals
Types of Chemical Reactions
| Type | Description | Example |
|---|---|---|
| Synthesis | A + B → AB | 2H₂ + O₂ → 2H₂O |
| Decomposition | AB → A + B | 2H₂O → 2H₂ + O₂ |
| Single replacement | A + BC → AC + B | Zn + 2HCl → ZnCl₂ + H₂ |
| Double replacement | AB + CD → AD + CB | AgNO₃ + NaCl → AgCl + NaNO₃ |
| Combustion | Fuel + O₂ → CO₂ + H₂O | CH₄ + 2O₂ → CO₂ + 2H₂O |
Balancing Chemical Equations
Law of Conservation of Mass: Atoms are neither created nor destroyed.
Steps:
- Count atoms on each side
- Add coefficients to balance
- Check your work
Example: Balance H₂ + O₂ → H₂O
- Unbalanced: 2 H, 2 O → 2 H, 1 O
- Balanced: 2H₂ + O₂ → 2H₂O
Acids and Bases
| Property | Acids | Bases |
|---|---|---|
| pH | Below 7 | Above 7 |
| H⁺ ions | Donate H⁺ | Accept H⁺ |
| Taste | Sour | Bitter |
| Feel | — | Slippery |
| Examples | HCl, vinegar, citrus | NaOH, ammonia, soap |
pH Scale
| pH | Classification | Examples |
|---|---|---|
| 0-2 | Strong acid | Stomach acid (pH 1-2) |
| 3-6 | Weak acid | Coffee (pH 5), urine (pH 6) |
| 7 | Neutral | Pure water |
| 8-11 | Weak base | Blood (pH 7.4), baking soda |
| 12-14 | Strong base | Bleach (pH 13) |
Solutions
| Term | Definition |
|---|---|
| Solute | Substance being dissolved (smaller amount) |
| Solvent | Substance doing the dissolving (larger amount) |
| Solution | Homogeneous mixture of solute and solvent |
| Concentration | Amount of solute per unit of solution |
Types of solutions:
- Saturated: Maximum solute dissolved
- Unsaturated: Can dissolve more solute
- Supersaturated: More solute than normally possible
Factors Affecting Solubility
| Factor | Effect on Solubility (solid in liquid) |
|---|---|
| Temperature | Usually increases solubility |
| Pressure | Little effect on solids |
| Stirring | Speeds dissolving (not amount) |
| Particle size | Smaller particles dissolve faster |
Energy in Reactions
| Type | Energy | Temperature |
|---|---|---|
| Exothermic | Releases energy | Feels warm |
| Endothermic | Absorbs energy | Feels cold |
Healthcare Chemistry Applications
| Application | Chemistry Concept |
|---|---|
| Blood pH regulation | Acid-base balance |
| Medication concentration | Solutions |
| IV fluids | Osmolarity |
| Drug interactions | Chemical reactions |
Test Your Knowledge
What type of bond involves the sharing of electrons?
A
B
C
D
Test Your Knowledge
A substance with a pH of 3 would be classified as:
A
B
C
D
Test Your Knowledge
In the equation 2H₂ + O₂ → 2H₂O, what type of reaction is this?
A
B
C
D