chem

Matter

Anything that has mass and takes up space

Element

Pure substance made of only one type of atom

Compound

Substance made of two or more elements chemically bonded

Mixture

Physical combination of substances that are not chemically bonded

Physical change

Change in form or state but not chemical composition (example: ice melting)

Chemical change

Change that forms a new substance (example: burning wood)

Solid

Matter with fixed shape and volume

Liquid

Matter with fixed volume but takes shape of container

Gas

Matter with no fixed shape or volume

Atom

Smallest unit of an element that retains its properties

Proton

Positive particle in nucleus — determines atomic number

Neutron

Neutral particle in nucleus — adds mass to atom

Electron

Negative particle outside nucleus — involved in bonding

Atomic number

Number of protons in an atom

Atomic mass

Protons + neutrons in an atom

Ionic bond

Bond formed when electrons are transferred between atoms (metal + nonmetal)

Covalent bond

Bond formed when atoms share electrons (nonmetal + nonmetal)

Solute

Substance that is dissolved in a solution

Solvent

Substance that dissolves the solute (usually water)

Solution

Homogeneous mixture of solute and solvent

Acid

Substance with pH less than 7 — releases hydrogen ions (H⁺)

Base

Substance with pH greater than 7 — accepts hydrogen ions (H⁺)

Neutral

pH of 7 — equal hydrogen and hydroxide ions

Conservation of mass

Matter is not created or destroyed in a chemical reaction — only rearranged