wunder beta⚗️ Intro to Chemistry
From atoms and the periodic table to bonds, reactions, and the chemistry hiding in your kitchen.
What you’ll learn
- Atoms: The Building BlocksDescribe the structure of the atom and how protons, neutrons, electrons, isotopes, and ions define matter.Atoms have a dense nucleus of positive protons and neutral neutrons surrounded by negative electrons, with almost all mass in the nucleus. The number of protons, the atomic number, defines the element. Varying the neutron count gives isotopes of different mass, and the periodic table's atomic mass is a weighted average of them. Gaining or losing electrons turns a neutral atom into a charged ion.
- Elements and the Periodic TableExplain what an element is and how the periodic table's layout and trends reflect electron arrangement.An element is a substance of one kind of atom, defined by atomic number. Mendeleev arranged the elements so properties recurred periodically, even predicting undiscovered ones. Rows are periods and columns are groups; elements in a group share valence electrons and behave alike, from reactive alkali metals to inert noble gases. Trends in size, reactivity, and electronegativity follow from nuclear charge and electron shells.
- Chemical BondsDistinguish ionic, covalent, and polar bonds and explain why atoms bond at all.Atoms bond to fill their outer electron shells and reach a stable, lower-energy state. Ionic bonds transfer electrons, forming charged ions that lock into crystal lattices like table salt. Covalent bonds share electron pairs, forming discrete molecules like water and methane. When sharing is uneven, the bond is polar, as in water, whose polarity underlies much of its life-supporting behavior.
- Molecules and CompoundsRead chemical formulas and distinguish molecules, compounds, and mixtures.A molecule is bonded atoms; a compound is a molecule of more than one element, with properties unlike its ingredients. Chemical formulas use symbols and subscripts to state exact composition, like H2O or C6H12O6. Compounds have elements chemically bonded in fixed ratios and need a reaction to separate, whereas mixtures are physically combined and can be separated by physical means.
- Reactions and Conservation of MassExplain chemical reactions, conservation of mass, balancing equations, and reaction energy.A reaction breaks and forms bonds, turning reactants into products while conserving atoms and total mass, a law Lavoisier established by careful weighing. Equations are balanced by adjusting coefficients, never subscripts, so each element matches on both sides. Reactions also move energy: exothermic ones release heat or light, endothermic ones absorb it, and many need activation energy to begin.
- Acids, Bases, and pHDefine acids and bases, interpret the pH scale, and measure acidity with indicators.Acids release hydrogen ions and bases accept them or release hydroxide ions, and mixing them neutralizes to form water and a salt. The pH scale runs 0 to 14, with 7 neutral, lower acidic, higher basic, and is logarithmic so each unit is a tenfold change. Indicators like litmus, universal indicator, and red cabbage reveal pH by color, while a pH meter reads it precisely.
- States of MatterExplain the states of matter, changes of state, and temperature as particle motion.Solids hold shape and volume with fixed, vibrating particles; liquids keep volume but flow; gases spread to fill space. Adding or removing heat drives changes of state, melting, boiling, condensing, freezing, subliming, which are physical changes leaving the substance unchanged. Temperature measures particle motion, so heating speeds particles up and cooling slows them toward absolute zero.
- Chemistry in Daily LifeConnect core chemistry to cooking, batteries, and soap, and meet the field's pioneers.Cooking is chemistry: the Maillard reaction browns food, leavening releases carbon dioxide, and heat denatures proteins. Batteries convert chemical reactions into electricity through controlled electron transfer. Soap cleans because its molecules have a water-loving and an oil-loving end that trap grease in micelles. Pioneers like Lavoisier, Mendeleev, and Curie built the science through careful measurement.
Questions this course answers
Where is nearly all of an atom's mass located?
Protons and neutrons sit in the nucleus and are about 2000 times heavier than electrons, so almost all the mass is concentrated there.
What determines which element an atom is?
The atomic number, the count of protons, defines the element. Change the proton count and you change the element itself.
An atom that has lost an electron becomes what?
Losing a negative electron leaves the atom with more protons than electrons, so it carries a net positive charge and is called a cation.
What insight let Mendeleev predict undiscovered elements?
Mendeleev saw properties recur in a periodic pattern, so he left gaps and predicted the properties of elements that would fill them, like gallium.
Why do elements in the same group of the periodic table behave similarly?
Chemistry is governed by outer electrons, and elements in a group share the same valence electron count, so they react in similar ways.
Why are the noble gases in Group 18 almost unreactive?
A full outer shell is the stable arrangement atoms seek, so the noble gases have no drive to gain, lose, or share electrons.
Grounded in trusted sources
- Royal Society of Chemistry
- Encyclopaedia Britannica
- US National Institute of Standards and Technology
- IUPAC (International Union of Pure and Applied Chemistry)
Every Wunder lesson is built from real, reputable sources — never invented.
Related Science courses
Wunder is a personalized learn-anything platform — tell it any topic and it builds a beautiful, fact-checked course in minutes, with narration, a knowledge check, and a college-style University track.
Browse more Science courses · All topics · Home
© 2026 Wunder Learning LLC · Terms & Privacy