Quantifying Reactants and Products

Front

Stoichiometry Noun

---

[stoy-kee-om-i-tree]

Back

Stoichiometry

---

The calculation of relative quantities of reactants and products in chemical reactions using a balanced chemical equation.

---

Example: This diagram shows a balanced chemical reaction, demonstrating how specific quantities of reactants (methane and oxygen) rearrange to form specific quantities of products.

Front

Reactants Noun

---

[ree-ak-tuhnts]

Back

Reactants

---

The starting materials in a chemical reaction that are consumed during the process and found on the equation's left side.

---

Example: This diagram shows a chemical reaction where hydrogen (H₂) and oxygen (O₂) are the reactants, the starting materials on the left of the arrow.

Front

Products Noun

---

[prod-uhkts]

Back

Products

---

The substances that are formed as a result of a chemical reaction, appearing on the right side of the equation.

---

Example: In a chemical reaction, reactants like methane and oxygen rearrange their atoms to form new substances called products, such as carbon dioxide and water.

Front

Balanced Chemical Equation Noun

---

[bal-uhnsd kem-i-kuhl ee-kwey-zhuhn]

Back

Balanced Chemical Equation

---

A chemical equation in which the number of atoms for each element is equal on both the reactant and product sides.

---

Example: The image shows that the total mass of chemicals before a reaction (reactants) is equal to the total mass after the reaction (products).

Front

Coefficients Noun

---

[koh-uh-fish-uhnts]

Back

Coefficients

---

Numbers placed before chemical formulas in an equation to indicate the relative number of moles of each substance involved.

---

Example: This image shows a coefficient (the number '6') in a chemical equation, indicating the number of molecules needed to balance the reactants and products.

Front

Law of Conservation of Mass Noun

---

[law uv kon-ser-vey-shuhn uv mas]

Back

Law of Conservation of Mass

---

The principle stating that mass is neither created nor destroyed during a chemical reaction; atoms are simply rearranged.

---

Example: This diagram shows a chemical reaction where atoms are rearranged, not lost. Counting the atoms on the left (reactants) and right (products) shows they are equal.

Front

Atom Noun

---

[at-uhm]

Back

Atom

---

The smallest fundamental unit of a chemical element that retains the properties of that element and can exist independently.

---

Example: This diagram shows an atom's basic structure: a central nucleus with protons and neutrons, surrounded by electrons orbiting in shells.

Front

Molecule Noun

---

[mol-i-kyool]

Back

Molecule

---

A neutral group of two or more atoms held together by covalent chemical bonds, representing the smallest unit of a compound.

---

Example: This diagram shows a single water molecule, which is made of two hydrogen (H) atoms chemically bonded to one oxygen (O) atom.

Front

Mole (mol) Noun

---

[mohl]

Back

Mole (mol)

---

The SI unit for the amount of a substance, defined as containing exactly 6.022 x 10^23 elementary entities.

---

Example: A mole is a specific quantity of a substance, equal to 6.022 x 10^23 particles. For the element carbon-12, one mole has a mass of exactly 12 grams.

Front

Molar Mass Noun

---

[moh-ler mas]

Back

Molar Mass

---

The mass of one mole of a given substance, which is typically expressed in units of grams per mole (g/mol).

---

Example: The molar mass of a compound (like water, H₂O) is found by adding the atomic masses of each atom in the molecule.