Ch 2

Matter

Anything that has mass and occupies space.

Physical Change

A change in appearance without producing a new substance.

Chemical Change

A change that produces a new substance.

Element

A pure substance made of one type of atom.

Atom

The smallest unit of an element.

Atomic Number

The number of protons in an atom, which determines the element.

Atomic Mass

The sum of protons and neutrons in an atom.

Isotope

Atoms of the same element with different numbers of neutrons.

Electron Shells

The outer shell of an atom that determines its reactivity.

Ionic Bond

A chemical bond formed by the transfer of electrons.

Covalent Bond

A bond formed by the sharing of electrons between atoms.

Cation

An ion with a positive charge, formed by losing electrons.

Anion

An ion with a negative charge, formed by gaining electrons.

Electrolytes

Ions that conduct electricity in solution and are essential for body functions.

Molecule

Two or more atoms bonded together.

Compound

A substance made from two or more different elements.

Water

Essential molecule that serves as a universal solvent and regulates body temperature.

Oxygen

Used to create ATP, essential for energy production.

Carbon Dioxide

A waste product of metabolism, affects blood pH.

Enzymes

Biological catalysts that speed up chemical reactions without being consumed.

Acid

A substance that releases H⁺ ions and decreases pH.

Base

A substance that accepts H⁺ ions and increases pH.

ATP

The cell's energy currency, produced from food.