Significant Figures, Calculations, and Atomic Theory

A comprehensive set of flashcards covering significant figures, calculations in chemistry, and atomic theory.

Significant Figures

Digits in a measurement that are known with certainty plus one additional digit that contains some uncertainty.

Precision

The degree to which repeated measurements under unchanged conditions show the same results.

Rounding Rules

If the digit following the last significant figure is 1-4, round down; if 6-9, round up.

Dimensional Analysis

A method for converting units by using conversion factors corresponding to known quantities.

Exact Values

Values that are used in calculations representing an exact relationship and contain no uncertainty.

Intermediate Values

Values that may be calculated as part of a longer calculation but are not the final result, kept to avoid rounding errors.

Atomic Number (Z)

The number of protons in the nucleus of an atom, defining the element's identity.

Protons and Neutrons

Subatomic particles in the nucleus of an atom, protons are positively charged, neutrons have no charge.

Electron

A negatively charged subatomic particle that orbits the nucleus of an atom.

Ion

A charged atom formed when an atom gains or loses electrons.

Anion

A negatively charged ion formed when a neutral atom gains one or more electrons.

Cation

A positively charged ion formed when a neutral atom loses one or more electrons.

Isotope

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

Mass Number (A)

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