Chemistry FAQ
Find answers to common questions about learning chemistry, the periodic table, chemical reactions, balancing equations, and pH.
What is the periodic table?
The periodic table organizes all known chemical elements by atomic number, electron configuration, and recurring chemical properties. Elements are arranged in 7 periods (rows) and 18 groups (columns). Elements in the same group have similar properties because they have the same number of valence electrons.
How do I balance chemical equations?
Balance chemical equations by adjusting coefficients (numbers in front of formulas) to ensure the same number of each type of atom appears on both sides. Never change subscripts. Start with elements appearing once, balance polyatomic ions as units, and save oxygen and hydrogen for last.
What is pH and how is it calculated?
pH measures acidity or alkalinity on a scale of 0-14, with 7 being neutral. The formula is pH = -log[H⁺], where [H⁺] is hydrogen ion concentration in moles per liter. Values below 7 are acidic, above 7 are basic. The scale is logarithmic—each whole number change represents a tenfold change in acidity.
What are the main groups in the periodic table?
Main groups include: Group 1 - Alkali metals (reactive, +1 ions), Group 2 - Alkaline earth metals (+2 ions), Groups 3-12 - Transition metals (multiple oxidation states), Group 17 - Halogens (reactive nonmetals, -1 ions), Group 18 - Noble gases (unreactive, full valence shells).
How do I calculate molar mass?
Molar mass is calculated by adding the atomic masses of all atoms in a chemical formula. For example, water (H₂O) has molar mass = (2 × 1.008) + 16.00 = 18.016 g/mol. Find atomic masses on the periodic table and multiply by the number of each atom in the formula.
What is the difference between acids and bases?
Acids donate hydrogen ions (H⁺) in solution and have pH below 7. Examples include hydrochloric acid (HCl) and acetic acid (vinegar). Bases accept hydrogen ions (or donate OH⁻) and have pH above 7. Examples include sodium hydroxide (NaOH) and ammonia (NH₃).
What are the states of matter?
The four main states of matter are solid (fixed shape and volume), liquid (fixed volume, takes shape of container), gas (no fixed shape or volume, fills container), and plasma (ionized gas, found in stars). Phase changes occur when energy is added or removed.
How do I use chemistry simulations?
Chemistry simulations let you conduct virtual experiments safely. You can mix chemicals, observe reactions, measure pH, explore the periodic table interactively, and visualize molecular structures. Adjust variables like concentration, temperature, and pressure to see how they affect chemical behavior.