Chem 109A Chapter 1.2 Notes

Matter

Stuff in the universe that has mass and occupies volume.

States of Matter

Solid, liquid, gas, plasma, and Bose-Einstein condensate.

Plasma

A high-energy state where electrons are separated from nuclei, common in stars.

Bose-Einstein condensate

A state of matter achieved at ultra-low temperatures where particles occupy the same quantum state.

Composition

The parts or components of matter.

Properties

Observable characteristics of matter.

Solid

Particles are tightly packed, maintain shape and volume, exhibit vibrational motion.

Liquid

Particles have more space than in a solid, flows and takes the shape of its container, has definite volume.

Gas

Large spaces between particles, easily compressed, expands to fill the shape and volume of its container.

Phase Coexistence

When matter exhibits all three states (solid, liquid, gas) at the same time (e.g., melting ice).

Atom

Basic unit of matter, consisting of a nucleus (protons and neutrons) and an electron cloud.

Electron

Negatively charged particle forming an electron cloud around the nucleus.

Nucleus

Contains protons and neutrons (nucleons) at the center of an atom.

Element

A pure substance containing only one type of atom. There are 118 discovered so far.

Neutral Element

An element with the same number of protons and electrons (Z = P = E).

Noble Gases

Group 18 elements, largely nonreactive due to complete valence electron shells.

Alkali Metals

Group 1 (first column) of the periodic table.

Alkaline Earth Metals

Group 2 (second column) of the periodic table.

Molecule

Two or more atoms chemically combined in specific geometric arrangements.

Diatomic Molecule

A molecule containing exactly two atoms.

Seven Diatomic Molecules

H2, N2, O2, F2, Cl2, Br2, I_2