Physics 2.1-2.2

Relationship between atoms and elements

Atoms are the smallest unit of matter that still has the properties of an element. An element is a substance made up of only one kind of atom.

Ages of atoms vs. ages of materials they compose

Atoms are billions of years old, created during the early universe, while the materials they compose (like rocks, living things, or manufactured objects) are much younger and change form over time.

Examples showing small size of atoms

A human hair is about 1,000,000 atoms wide; a single sheet of paper is about 100,000 atoms thick.

Evidence for the existence of atoms

Brownian motion, scanning tunneling microscope images, and Rutherford’s gold foil experiment all provide evidence for atoms.

Atom vs. molecule

An atom is a single particle of an element, while a molecule is two or more atoms chemically bonded together.

Element vs. compound

An element is made of only one type of atom, while a compound is a substance formed by two or more different elements chemically combined.

Three basic building blocks of an atom and where they’re found

Protons (in the nucleus), neutrons (in the nucleus), and electrons (in the electron cloud around the nucleus).

Significance of horizontal rows (periods) and vertical columns (groups) in the periodic table

Periods show increasing atomic number and energy levels, while groups/families contain elements with similar chemical properties.

How plasma differs from solids, liquids, and gases

Plasma is an ionized state where atoms lose electrons, creating charged particles. Unlike solids, liquids, and gases, plasma conducts electricity and responds to magnetic fields.