Chemical Reactions

for test

Physical Properties

Observable characteristics of material without changing its chemical makeup (e.g., color, hardness).

Chemical Properties

Describe how a substance interacts with others (e.g., flammability, reactivity with acids).

Physical Change

A change where the substance’s form alters but its chemical makeup remains (e.g., melting ice).

Chemical Change

A change that alters the substance's composition, resulting in new substances (e.g., rusting iron).

Indicators of a Chemical Change

Signs that a chemical change has occurred, such as color change and gas formation.

Reactants

The starting substances in a chemical reaction.

Products

The substances formed after a chemical reaction occurs.

Rate of Reaction

The speed at which reactants are converted into products in a chemical reaction.

Wanted Reactions

Reactions that have beneficial outcomes (e.g., photosynthesis, baking).

Unwanted Reactions

Reactions that have negative outcomes (e.g., rusting, food spoilage).

Elements

Pure substances that consist of only one type of atom.

Atoms

The smallest particles of an element that retain its chemical properties.

Molecules

Groups of atoms bonded together.

Nucleus of an Atom

The central part of an atom containing protons and neutrons.

Compounds

Substances formed by two or more different atoms bonded together (e.g., H₂O).

Mixtures

Combinaions of elements or compounds that are not chemically bonded (e.g., air).

Symbol for Oxygen

O₂, a colorless and odorless gas that supports combustion.

Symbol for Hydrogen

H₂, a highly flammable and lightest gas.

Symbol for Carbon Dioxide

CO₂, a non-flammable gas that is denser than air.

Chemical Test for Oxygen

Relights a glowing splint.

Chemical Test for Carbon Dioxide

Turns limewater cloudy.

Chemical Test for Hydrogen

Produces a popping sound with a lit splint.

Environmental Effect of CO₂

Contributes to global warming and leads to ocean acidification.