TEAS 7 Chemistry Crash Guide: Balancing Equations, pH & Bonds

Chemistry Is Predictable — Use That

Chemistry makes up roughly a fifth of the TEAS Science section — about 8 questions — and it ambushes students who spent all their time on anatomy. Here is the reassuring part: TEAS chemistry is high-school general chemistry with no organic molecules, no thermodynamics, and no advanced math. Six self-contained topics cover nearly every question, and each one runs on a small set of rules. Learn the rules and this becomes one of the easiest places to bank Science points.

This crash guide covers all six topics in study order — atomic structure, the periodic table, bonding, reactions and balancing, acids and bases, and solutions — with worked examples in true exam style.

Atomic Structure: Protons Define Everything

Particle	Charge	Location	Mass
Proton	Positive	Nucleus	About 1 amu
Neutron	Neutral	Nucleus	About 1 amu
Electron	Negative	Shells around nucleus	Nearly zero

Three numbers define any atom. The atomic number equals the proton count and identifies the element — every carbon atom has 6 protons, no exceptions. The mass number equals protons plus neutrons. Atoms of one element with different neutron counts are isotopes. Atoms that gain or lose electrons become ions: cations are positive (lost electrons), anions are negative (gained electrons). A handy memory hook: cats have paws — cations are positive; an anion sounds like "a negative."

The Periodic Table: Read It, Don't Memorize It

You will not need to recite the table, but you must read its organization. Horizontal rows are periods (each row adds an electron shell); vertical columns are groups whose members share properties because they carry the same number of valence electrons. Know the four famous groups: alkali metals (Group 1, one valence electron, very reactive), alkaline earth metals (Group 2, two valence electrons), halogens (Group 17, seven valence electrons, reactive nonmetals), and noble gases (Group 18, full shells, inert). Metals sit left of the stair-step line, nonmetals right — and that position predicts bonding, which comes next.

Chemical Bonding: Transfer or Share

Bond	What happens	Forms between	Example
Ionic	Electrons transfer	Metal + nonmetal	NaCl table salt
Covalent	Electrons shared	Nonmetal + nonmetal	H2O water
Hydrogen	Weak attraction	H with O, N, or F	Between water molecules

The one-line test for any bonding question: transfer means ionic, share means covalent. Atoms bond to fill their outer shell — the octet rule of eight valence electrons. When sodium (a metal) meets chlorine (a nonmetal), sodium donates an electron and they lock together ionically; when two nonmetals like hydrogen and oxygen meet, they share instead.

Reactions and Balancing Equations

Learn the five reaction patterns by shape, since the exam often asks you to classify rather than compute:

Type	Pattern	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 obeys the law of conservation of mass: atoms are never created or destroyed, so each element needs equal counts on both sides. Adjust only the coefficients (big numbers in front) — never the subscripts inside formulas. Worked example: H2 + O2 → H2O is unbalanced (2 oxygen left, 1 right). Put 2 before water (2H2O gives 4 H, 2 O), then 2 before H2: 2H2 + O2 → 2H2O. Check: 4 hydrogen and 2 oxygen on each side. Balanced.

Acids, Bases, and the pH Scale

Property	Acids	Bases
pH	Below 7	Above 7
Hydrogen ions	Donate H+	Accept H+
Taste and feel	Sour	Bitter, slippery
Litmus paper	Turns red	Turns blue
Examples	HCl, vinegar, citrus	NaOH, ammonia, soap

The pH scale runs 0 to 14 and is logarithmic: each whole-number step means a tenfold change in hydrogen-ion concentration. A pH 3 solution is ten times more acidic than pH 4 — and a pH 2 solution is 10 × 10 × 10 = 1,000 times more acidic than pH 5. Pure water is neutral at 7, and human blood is held near 7.4 by bicarbonate buffers. An acid plus a base undergoes neutralization, producing salt and water: HCl + NaOH → NaCl + H2O.

Solutions, Concentration, and States of Matter

A solution is a solute dissolved in a solvent, and concentration is usually given as molarity: moles of solute per liter of solution. Adding solvent dilutes the solution and lowers molarity. Reactions that release energy are exothermic; those absorbing energy are endothermic. For states of matter, remember the particle story: solids hold fixed shape and volume with vibrating packed particles, liquids keep volume but take the container's shape, and gases fill both. Melting or boiling changes form only (physical change); burning or rusting creates a new substance (chemical change).

5 Traps That Catch Chemistry Students

1. Changing subscripts to balance. Only coefficients move — touching subscripts rewrites the substance itself.
2. Treating pH as linear. Every unit is a factor of ten, not one more unit of acidity.
3. Forgetting the pulmonary-style exceptions. Not chemistry, but the same lesson: definitions have edge cases, and the TEAS loves them.
4. Confusing mass number with atomic mass. Mass number is protons plus neutrons in one atom; atomic mass is the weighted average across isotopes.
5. Calling dissolving a chemical change. Salt in water is still salt and water — no new substance, so it is physical.

Study Checklist

• Compute protons, neutrons, and electrons for any element from its atomic number and mass number.
• Classify any bond as ionic or covalent from the elements involved.
• Balance a synthesis or combustion equation using coefficients only.
• Calculate pH strength differences as powers of ten.
• Sort any change as physical or chemical with one reason.

Chemistry rewards rule-learners. Six topics, a handful of patterns, and consistent practice with balancing and pH math will convert this ambush section into reliable points.