Chemical Compounds
A compound is a pure substance formed from atoms of two or more elements, characterized by their
unique properties and limited resources. Ionic compounds, formed by non-metals and metals, are a type
of compound. Covalent bonds, formed by the simultaneous attraction of two nuclei for a shared pair of
electrons, are a fundamental concept in chemistry.
Solutions and Mixtures
A solution is a homogeneous mixture of dissolved substances, consisting of a solute and a solvent. A
concentrated solution contains a high ratio of solute to solvent. The mole ratio refers to the ratio of
coefficients in a balanced chemical equation.
Properties of Solutions
Qualitative properties of solutions are attributes that can be observed with one or more of the five
senses. Standard solutions have precisely known concentrations.
Atomic Structure
Valence electrons are the electrons that occupy the outermost energy level in an atom. Electrons are
negatively charged particles located in the region surrounding the nucleus. Neutrons and protons are
neutrally and positively charged