Chemistry Vocabulary

Alchemy
The prescientific investigation of substances, including the search for ways to change common metals into gold.
Atmosphere
The layer of gases surrounding a planet.
Atom
The smallest particle of an element.
Atomic number
The number assigned to an element, based on the number of protons in the nucleus of its atom.
Average kinetic energy
Temperature.
Blood plasma
The clear, amber solution that is the liquid portion of blood.
Bond
An attractive force acting between atoms.
Calibrated
Divided into units that correspond to a standard.
Calorie
The unit of energy that will raise the temperature of 1 gram of water 1 degree Celsius.
Carbohydrate
A group of carbon-based nutrients, including sugars and starches.
Carbon dioxide gas
A compound made from carbon and oxygen; CO2.
Chemical equation
A representation of a chemical reaction using chemical formulas.
Chemical formula
A code that represents the number and kinds of atoms in one particle of a substance.
Chemical property
A characteristic of a substance that determines how it interacts with other substances.
Chemical reaction
A process during which starting substances (reactants) change into new substances (products) with different arrangements of atoms.
Combustion
A chemical reaction, commonly called burning.
Compound
A substance whose particle is made of two or more different kinds of atoms.
Compressed
Reduced in volume as a result of applied pressure.
Concentrated
A solution with a large amount of solute dissolved in a small amount of solvent.
Concentration
The amount of solute dissolved in a measure of solvent.
Condensation
The change of phase from gas to liquid.
Conduction
The transfer of energy (heat) from one particle to another as a result of contact.
Conserved
Unchanged.
Contraction
The reduction of volume of a sample of matter as a result of cooling.
Crust
Earth’s hard outer layer of solid rock.

Cyclotron
An instrument used to create new elements.
Density
The ratio of mass and volume in a sample of matter.
Deposit
The change of phase from gas directly to solid.
Dilute
A solution with a small amount of solute dissolved in a large amount of solvent.
Dissolve
To incorporate one substance uniformly into another substance at the particle level.
Dry ice
The solid phase of carbon dioxide.
Electron
A subatomic particle with a negative charge.
Element
A fundamental substance that cannot be broken into simpler substances by chemical or physical processes.
Energy transfer
The movement of energy from one location to another.
Equilibrium
A condition in which a system is experiencing no net change.
Evaporation
The change of phase from liquid to gas.
Expansion
An increase of volume.
Force
A push or a pull.
Freeze
To change phase from liquid to solid.
Fundamental
Simple and basic.
Gas
A phase of matter that has no definite shape or volume. Particles of gas fly independently through space.
Gaseous
Existing in the gas phase.
Global warming
The increase of average temperature worldwide.
Heat of fusion
Heat that causes the solid/liquid phase change without changing the temperature of the substance.
Herbicide
A plant poison.
Hydrocarbon
A group of carbon-based substances made of carbon and hydrogen only.
Insoluble
Not capable of being dissolved. Sand is insoluble in water.
Kinetic energy
Energy of motion.
Lava
Molten rock flowing on Earth’s surface.
Lipid
A group of organic substances that includes oils and fats.
Liquid
A phase of matter that has definite volume but no definite shape. Particles of liquid are loosely bonded, but can flow over and around one another.
Mantle
The large rocky part of planet Earth, located between the core and the crust.
Mass
A measure of the quantity of matter.
Matter
Anything that has mass and takes up space.
Melt
To change phase from solid to liquid.
Metal
A group of elements that stretch, bend, and conduct heat and electricity.
Mixture
Two or more substances together.
Molecule
A particle made of two or more atoms that are held together with strong (covalent) bonds.
Neutron
A subatomic particle with no charge.
Nitrogen
A colorless, odorless, gaseous element that makes up about 78% of Earth’s atmosphere.
Noble gas
A gaseous element that does not react with other elements.
Nucleus
The center of an atom, composed of protons and neutrons.
Octane
An eight-carbon molecule. Octane is one of the main ingredients in gasoline.
Organic compound
A large class of substances produced by organisms.
Particle
The smallest piece of a substance that is still that substance.
Periodic table of the elements
A way to organize the elements based on atomic number and chemical property.
Phase
The physical appearance of a sample of matter based on the kinetic energy of its particles. Common phases include solid, liquid, and gas.
Phloem
A plant tissue that transports nutrients to all parts of the plant.
Physical property
A characteristic of a substance that can be observed without changing it chemically, such as size, shape, density, and phase
Potash
An impure form of potassium carbonate.
Precipitate
An insoluble product of a reaction.
Predict
To make an accurate estimation of a future event based on knowledge.
Product
A substance produced in a chemical reaction.
Protein
A group of nitrogen-containing organic substances.
Proton
A subatomic particle that has a positive charge.
Radiation
A form of energy that travels through space.
Radioactivity
Radiation given off by the elements.
Ratio
The relationship between two numbers.
Reactant
A starting substance in a chemical reaction.
Room temperature
The average kinetic energy of the particles in the air and other objects in a room.
Salt
The product that forms when a metal reacts with an acid.
Saturated
A solution with the maximum amount of dissolved solute.
Scanning tunneling microscope (STM)
An instrument that can create images of arrays of atoms.
Solid
A phase of matter that has definite volume and definite shape. The particles of a solid are tightly bonded and cannot move around.
Soluble
Capable of being dissolved. Table salt is soluble in water.
Solute
A substance that dissolves in a solvent to form a solution.
Solution
A mixture formed when one substance dissolves in another.
Solvent
A substance in which a solute dissolves to form a solution.
Sublime
To change phase from solid to gas.
Substance
A type of matter defined by a unique particle.
Transparent
Matter through which an image can be seen clearly.
Vibrating
Moving rapidly back and forth.
Volume
A defined quantity of space.
Water vapor
The gas phase of water.
Well-ordered array
A repeating pattern.
Xylem
A plant tissue that transports water and minerals to all parts of the plant.