Chemistry key terms

The requirement that the total electrical charge is equal on both sides of an ionic or half equation.

The principle that energy cannot be created or destroyed, although it can be transferred between stores and between a system and its surroundings.

The principle that atoms are neither created nor destroyed in a chemical reaction, so the total mass of reactants equals the total mass of products.

A final mass that no longer changes after repeated cycles of heating, cooling and weighing, indicating that the reaction is complete.

Unwanted material introduced into a sample or apparatus, which may produce a misleading result.

The circumstances surrounding an issue that affect which choice is appropriate.

Manufacture in which reactants are supplied and product is removed continually while the process operates.

A comparison used to check whether an observed change was caused by the factor being investigated.

A trial carried out without the substance being tested, used as a baseline for comparison.

Conditions kept consistent so that comparisons between experimental results are valid.

Adding and combining reagents in a way that controls their amounts and the conditions in which they react.

An action or feature that reduces the likelihood or severity of harm, such as using a smaller quantity, a safety screen or suitable eye protection.

A factor kept the same between experimental conditions so that a difference in results can be linked to the factor being tested.

Factors kept constant so that any change in the result can be attributed to the independent variable.

A fraction made from two equivalent measurements, such as $\frac{1000\text{ g}}{1\text{ kg}}$. Its value is one, so multiplying by it changes the unit but not the physical quantity.

A stated equality between two measurements of the same quantity, such as $1\text{ kg}=1000\text{ g}$, used to change the unit without changing the quantity.

A salt made when copper(II) oxide reacts with sulfuric acid; it forms a blue solution and blue hydrated crystals.

A relationship in which two measured variables change together; it does not, by itself, show that one causes the other.

The destruction of a material by chemical reactions with substances in its environment.

The ability of a material to withstand chemical attack by its surroundings.

Able to resist chemical attack by substances in the surroundings.

Able to attack and damage materials or living tissue, including skin and eyes.

A strong bond between atoms formed when they share a pair of electrons.

A strong bond formed when atoms share a pair of electrons.

A compound formed when non-metal atoms share pairs of electrons.

A substance made of atoms joined by bonds in which they share electrons.

The breakdown of large hydrocarbon molecules into smaller, more useful molecules.

The mass of crop harvested from a given area of land.

A small heat-resistant container used to heat a solid strongly.

A naturally occurring fossil fuel that is a complex mixture of hydrocarbons.