School in a Book: Chemistry

“So that’s what stuff is.” That’s an important realization. It could be a breakthrough moment in one’s education. Don’t underestimate young children’s ability to grasp many basic chemistry concepts, either; the earlier they start thinking about the big questions, the more interested and less intimidated they’ll be by them later on.

Like most other subjects, science is best learned through conversation. Experiments are great, too, but they’re not always necessary. If you have little kids who can’t yet handle close proximity to anything magnetic, explosive or filled with water, choose a few scientific concepts to talk about per day, and send the older kid to a more hands-on science class. (Video demonstrations, like those on YouTube, are great, too.)

That said, if you can manage it, there’s a huge number of great science project ideas out there, and hands-on projects are definitely a great memory aid.


Chemistry: The science of matter, including what it is and how it’s made

Chemical: Any substance made up of two or more atoms. Note that this word is also used to refer to human-synthesized substances; however, this is a colloquial usage.

Matter: Anything that is made of particles, takes up space (has volume), and has mass. It is one of only two “things” in the universe. The other is energy.

Weight: A measure of the force of gravity on something. It changes relative to where in space an object is located; for example, a book weighs less on the moon than on the earth.

Mass: A measure of something’s absolute heaviness (the amount of matter within it). It doesn’t change when the forces (such as the gravitational force) change because it is measured relative to an absolute standard (one kilogram).

Density: The measure of something’s mass per unit of volume. Objects with more of this are heavier than other objects that take up the same amount of space.

Particle: A very small unit of matter that has properties such as mass, charge, and spin. These include atoms, molecules, ions, protons, neutrons, and electrons. Note that physicists have also discovered other mysterious particles that don’t seem quite physical in nature.

The three states of matter: Solid, liquid and gas

Solid: A substance with a definite shape and definite volume

Liquid: A substance with definite volume but a varying shape

Gas: A substance without a definite shape or definite volume. Note that air is not a gas, but a mixture of gases and other particles. The various gases aren’t chemically bonded to each other, and can be separated without breaking any chemical bonds.

Atoms: The smallest units of matter that retain the chemical properties of an element; the building blocks of molecules. Each is made up of a nucleus containing protons and neutrons and a shell containing electrons that spin around the nucleus. They also contain other subatomic particles and a great deal of empty space. (The space between subatomic particles in an atom is relatively similar to the space between heavenly bodies in the universe.) Molecules are formed when atoms chemically bond together through sharing or transferring electrons. Note that whereas molecules can be easily split through everyday chemical reactions, atoms require extraordinary amounts of energy to split them. This is called atomic fission, and it is the basis of nuclear power. Also note that a sheet of paper is about one million atoms thick.

Subatomic particles: The incredibly tiny pieces of matter that make up atoms. They include protons, neutrons, electrons, quarks, and more. They cannot be separated from each other without using extraordinary amounts of energy. Some subatomic particles, like quarks, are too tiny to be directly observed.

Nucleus: The center part of an atom that holds protons and neutrons

Protons: The positively charged parts of an atom, which are located inside the nucleus. The number of protons in an atom corresponds to its element and its atomic number. For example, the oxygen atom has eight protons and its atomic number is eight.

Neutrons: The parts of an atom that contain no charge, are located inside the nucleus and, along with the protons, determine the atom’s mass number. The number of neutrons in an atom is variable, with each possible variation creating a different isotope of the same atom.

Electrons: The negatively charged parts of an atom, which are located outside the nucleus and spin around it, and that enable chemical bonding between atoms

Atomic shells: The layers within an atom that surround the nucleus and contain electrons. They are organized by energy level, with the electrons in the innermost shell having the lowest energy, and those in the outermost shell having the highest energy.

Quarks: Subatomic particles that make up protons and neutrons

Element: A substance that contains only one kind of atom

Isotope: A particular variation of an atom, which is determined by the number of neutrons in that atom. For example, carbon-12 and carbon-13 both have six protons but carbon-12 has six six neutrons and carbon-13 has seven neutrons. Isotopes of the same atom have different mass numbers from each other and might have some different physical properties but chemically they behave alike.

Molecule: Any chemically bonded group of atoms, whether atoms of the same type (which form an element) or atoms of different types (which form a compound). Molecule bonds can only be broken through chemical change. 

Compound: A combination of two or more substances that are chemically bonded together. The substances can’t be separated by physical means, only chemical reactions. An example is water, whose chemical bonds are broken only through chemical reactions.

Mixture: A combination of two or more substances that are not chemically bonded and can, therefore, be separated through physical means. An example is cake batter, which is a simple combination of ingredients that have not experienced molecular change.  

Periodic Table of the Elements: A chart listing each known element, organized by these elements’ atomic numbers

Atomic number: The number of protons in an atom, which indicates the atom’s chemical properties and, by extension, its substance type (element). The number of protons in an atom is the same as the number of electrons in an atom. 

Mass number: The total number of protons and neutrons in an atom

Chemical bonding: The joining of atoms to create molecules

Chemical reaction: The process that occurs when bonds between atoms in a substance are broken and the atoms rearrange to form new substances with different properties. An example is baking a cake: the cake is formed after heat changes the molecular structure of the batter.

Chemical symbol: The letters that represent the atoms of a particular element; for example, C for carbon

Chemical formula: A notation using chemical symbols and numbers to indicate the types and numbers of atoms present; for example, CO2 and H2O

Ion: A charged particle that is formed when an atom or molecule gains or loses one or more electrons. When an atom gains one or more electrons, it becomes a negatively charged ion, and when it loses one or more electrons, it becomes a positively charged ion.

Covalent bond: A chemical bond formed when atoms share electrons. Each atom still has its proper total number, but some of its electrons are attracted to the other atoms and stick there. Most non-metal elements are formed with covalent bonds.

Double bond: A chemical bond formed when two atoms share two electrons each with each other

Ionic bond: A chemical bond formed when one atom loses one or more electrons to another atom. This creates a positively charged ion in one atom and a negatively charged ion in the other, which are attracted to each other.

Metallic bond: A chemical bond between metal atoms formed when the atoms share a pool of electrons, which allow the metals to easily conduct electricity

Hydrogen (H): The most abundant element in the universe, which forms water when it is burned in oxygen and which can form compounds with most other elements

Helium (He): The second most abundant element in the universe, though is not abundant in the earth’s atmosphere due to its low atomic weight and high velocity

Oxygen (O): The third most abundant element in the universe, which helps plants and animals release energy from food through the process of cellular respiration

Carbon (C): The fourth most abundant element in the universe, which is found in all organic compounds and in more compounds overall than any other element

Water (H2O): The most common liquid on earth, one that is a universal solvent and necessary for life, and that is formed when two H2 molecules and one O2 molecule undergo a chemical reaction called combustion, releasing two H2O molecules and energy

Carbon dioxide (CO2): A greenhouse gas produced through plant respiration, decomposition of organic material, the burning of fossil fuels and more

Sodium chloride (NaCl): Table salt, a combination of a metal (sodium) and a non-metal (chlorine)

Carbon monoxide: A poisonous gas formed when fuels burn in a place with limited oxygen, such as an engine

Soluble: Able to dissolve in a solvent

Insoluble: Unable to dissolve in a solvent

Solution: The combination of a solvent and the substance that is dissolved in it

Corrosion: The damaging chemical reaction that occurs to a substance by its surrounding environment. For example, metal corrosion can occur when oxide forms on the surface of the metal.

Electrolysis: The separating of individual elements in a compound by passing an electric current through it when it is molten or in a solution

Salt: A chemical compound formed from the reaction of an acid with a base, which usually crystallizes in the form of cubes

Organic compound: Any compound that includes carbon (with a few exceptions)

Fermentation: The process in which yeast and some bacteria break down sugars or other organic compounds into simpler compounds like carbon dioxide to produce energy without the use of oxygen

Metal: An element or an alloy that is shiny in appearance; conducts heat and electricity; and usually remains solid at room temperature (though not always). Some, like iron and nickel, are also magnetic. Note that the definition of the term “metal” is not exact, and changes as its application changes. Some non-metal elements become metals at very high temperatures.

Alloy: A mixture of two or more metals or a metal and a different element to make a substance with enhanced usefulness

Semiconductor: A substance with some conduction, but not as much as a true conductor has

Acid: A chemical substance with a pH less than 7 that donates protons or hydrogen ions when dissolved in water, donates electrons to form chemical bonds and tastes sour when found in liquid solutions

Base/alkaline: A chemical substance with a pH greater than 7 that accepts protons from hydrogen ions in liquid solutions

pH: A measure of how acidic or basic a solution is. A pH of 7 is neutral, while a pH higher than 7 shows alkalinity and a pH of less than 7 shows acidity. Note that adding a base to an acid helps neutralize the acid and produces water and salts.

pH scale: The 14-point scale used to measure whether a liquid solution is basic, acidic or neutral

Endothermic reaction: A chemical process that absorbs heat

Exothermic reaction: A chemical process that emits heat

Oxidation: A chemical reaction in which a substance loses electrons, often by the addition of oxygen, causing it to change in some way. An example is the presence of iron oxide (rust) in metal exposed to water.

Reduction: A chemical reaction in which a substance gains electrons, often by the removal of oxygen, causing it to change in some way. An example is the conversion of iron oxide (rust) to iron in the presence of a reducing agent, such as hydrogen gas.

Oxidation-reduction (redox) reaction: A chemical reaction in which substance undergoes reduction, causing another to undergo oxidation. This happens because the substance undergoing reduction donates electrons to the other substance.


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