Chem Chapter 2: Atoms and Elements

Flashcards covering key concepts related to atoms, elements, and their properties.

Atom

The smallest identifiable unit of an element, consisting of protons, neutrons, and electrons.

Brownian Motion

The random motion of particles suspended in a fluid, confirming the particulate nature of matter.

Law of Conservation of Mass

In a chemical reaction, the total mass of the substances involved does not change.

Law of Definite Proportions

A given compound always contains the same proportion of elements by mass.

Isotope

Atoms of the same element with the same number of protons but different numbers of neutrons.

Atomic Number (Z)

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

Mass Number (A)

The total number of protons and neutrons in an atom's nucleus.

Ion

An atom that has gained or lost one or more electrons, thus acquiring an electric charge.

Cation

A positively charged ion that has lost one or more electrons.

Anion

A negatively charged ion that has gained one or more electrons.

Mole

A quantity of substance that contains 6.022 x 10^23 particles (Avogadro's number).

Avogadro's Number

The number of particles in one mole of a substance, approximately 6.022 x 10^23.

Molar Mass

The mass of one mole of a substance, usually expressed in grams per mole (g/mol).

Periodic Law

The properties of elements are periodic functions of their atomic number.

Mass Spectrometry

A technique that separates particles based on their mass to determine isotopic composition.