Unit 4: Reactions

Compounds

Elements that combine in whole number ratios and have their own unique properties

Chemical Formula

A combination of chemical symbols and numbers to represent a substance

Subscript

A number written slightly below and to the right of a chemical symbol that shows how many atoms of an element are in a compound.

Superscript

A number written slightly above and to the right of a chemical symbol that shows the charge of an element/polyatomic ion

Atomic Stability

Occurs when the element contains all of the electrons necessary to have a full outer shell

Lewis Dot Diagram

a representation of the valence electrons in an atom, using dots

Chemical Bond

the force that holds two atoms together in a compound

Ion

A charged atom

Cation

an atom that has lost electrons (positive charge)

Anion

an atom that has gained electrons (negative charge)

Covalent Bond

A chemical bond that involves sharing a pair of electrons between atoms in a molecule

Single Covalent Bond

a bond formed when two atoms share a two valence electrons

Double Bond

A chemical bond formed when two atoms share four valence electrons

Binary Compound

a compound composed of two elements

Polyatomic Ion

A charged group of covalently bonded atoms

Chemical Reaction

the process by which one or more substances change to produce one or more different substances

Reactant

A chemical substance that is present at the start of a chemical reaction

Product

A substance that is present at the end of a chemical reaction

Law of Conservation of Mass

the law that states that mass cannot be created or destroyed in ordinary chemical and physical changes

Coefficient

A number in front of a chemical formula in an equation that indicates how many molecules or atoms of each reactant and product are involved in a reaction.

Valence Electrons

Electrons on the outermost energy level of an atom