A change that forms one or more new substances with different properties. Example: Burning wood.

Clearly different or separate; easy to tell apart. Example: Salt is _____ from sugar in taste and appearance.

A process where reactants turn into products, forming new substances. Example: Baking soda + vinegar = bubbles.

A trait that helps identify a substance and stays the same no matter the amount. Example: Boiling point.

The amount of mass in a given volume. Formula: mass ÷ volume. Example: Steel is denser than water.

How well a substance dissolves in a liquid. Example: Sugar dissolves in water, sand does not.

The ability of a substance to catch fire. Example: Gasoline is very ______.

How harmful a substance is to living things. Example: Mercury is toxic to humans.

The temperature at which a liquid becomes a gas. Water boils at 100°C (212°F).

The temperature at which a solid becomes a liquid. Ice melts at 0°C (32°F).

A formula that shows what happens during a chemical reaction using symbols and arrows. Example: H₂ + O₂ → H₂O.

The new substances formed in a chemical reaction. Example: Water is the ________ of H₂ and O₂.

The starting substances in a chemical reaction. Example: H₂ and O₂ are _____ in making water.

The arrow (→) in a chemical equation showing the direction of the reaction—from reactants to products.

Mass cannot be created or destroyed in a chemical reaction; the total mass stays the same.

Energy is not created or destroyed—just changed from one form to another. Example: Chemical energy → heat.

Man-made substances created from natural resources. Example: Nylon, plastic.

Synthetic materials that can be molded and hardened. Example: Water bottles, containers.

Long chains of repeating molecules. Can be natural or synthetic. Example: Rubber, DNA, plastics.

Materials found in nature that humans use. Example: Water, coal, wood, oil.

Turning used materials into new products to reduce waste. Example: ________ aluminum cans into new ones.

The smallest unit of an element that keeps the properties of that element. Everything is made of atoms.

Two or more atoms bonded together. Can be the same or different elements. Example: O₂ or H₂O.

A substance made from two or more elements that are chemically bonded. Example: Water (H₂O).

Two or more substances physically combined. They are not chemically bonded. Example: Salt water or salad.

A pure substance made of only one type of atom. Example: Oxygen (O), Gold (Au).

The total motion energy of particles in a substance. Increases with heat.

A chemical reaction that absorbs heat from the surroundings. Example: Photosynthesis.

A chemical reaction that releases heat. Example: Burning wood or fireworks.