What is a polyatomic ion?

A polyatomic ion is a covalently bonded group of atoms that behaves as a single unit with a net positive or negative charge (e.g. Ammonium NH₄⁺, Carbonate CO₃²⁻).

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Core Study Guide

Elements & Nomenclature

Pure substances, mixtures, and the IUPAC naming system.

An element is a pure substance consisting of only one type of atom. Compounds represent chemically combined elements.

This unit covers elements, homogenous/heterogenous mixtures, and the standard rules for writing and naming chemical formulas (IUPAC nomenclature).

Key Takeaways

•Elements cannot be broken down into simpler substances by chemical means.
•Mixtures are physically combined substances that retain their individual chemical properties.
•Nomenclature rules dictate how binary ionic and covalent compounds are named.

Core Concepts & Definitions

1Elements, Compounds, and Mixtures

Matter is classified based on purity and physical combination status.

•Elements: gold, oxygen (pure atoms).

•Compounds: water, carbon dioxide (chemically bonded elements).

•Mixtures: air, saltwater (physically mixed).

Quick Revision Notes

•In ionic nomenclature, the cation is always named first, followed by the anion (with -ide ending).
•Roman numerals are used for transition metals with variable oxidation states (e.g. Iron(III) Chloride is FeCl3).