Grade 9/10 Chemistry Review Ms. Richardson SCH3U/4C

Safety in the Laboratory Always wear protective clothing when using materials that could shatter or splash Goggles, lab coat, etc. Be aware of the safety equipment that is available and where they are located Fire blanket, fire extinguisher, eye-wash station Know the proper procedures for using safety equipment

Safety in the Laboratory Follow instructions for proper disposal of broken glass and chemicals WHMIS (Workplace Hazardous Materials Information System) symbols are used in Canada to identify dangerous materials

The Atom The atom is the basic unit of a chemical element. Atoms are indivisible, and are made up of 3 subatomic particles: Positive protons (p+) Neutral neutrons (n0) Negative Electrons (e-)

Compounds & Molecules Two or more different atoms chemically combine to form compounds. A molecule is the smallest form of any element or compound that has the properties of that substance. Diatomic molecules are molecules composed of 2 atoms of the same element. There are 7 diatomic molecules.

Chemical Symbols Every element has a unique chemical symbol that is universally recognized The chemical symbol for an element is typically made up of 1-2 letters Only the first letter of the chemical symbol is upper case You should be familiar with the names and symbols for the first 20 elements

Standard Atomic Notation We can describe elements through standard atomic notation

Chemical Changes During chemical reactions, a new substance is produced. The properties of the new substance(s) will differ from the properties of the original substance(s). Evidence that a chemical change has occurred: Gas forms (bubbles/fizzing) Precipitate (solid) forms from two liquids Heat is released/absorbed Light is produced The colour changes

Ionic Compounds An ionic compound forms when one or more electrons are transferred from a metal to a non-metal atom.

The Octet Rule Atoms tend to combine in such a way that each atom has eight electrons in its valence (outermost) shell. This is accomplished through one of two ways: The transfer of electrons (ionic compounds) The sharing of electrons (covalent/molecular compounds)

Ionic Compounds Ionic compounds form when one or more electrons are transferred from a metal atom to a non-metal atom. Atoms that lose electrons become cations (positive ions) Atoms that gain electrons become anions (negative ions) The amount of the charge is based on the number of electrons transferred.

Polyatomic Ions Ionic compounds can be composed of polyatomic ions. A polyatomic ion is a group of atoms that act as a single unit and have a charge.

Naming Ionic Compounds Example: NaCl sodium sodium chlor- sodium chloride Most ionic compounds can be named by following these steps: Write the name of the metal. Next, write the prefix of the non-metal. Change the ending of the non-metal to –ide. ** What about naming ionic compounds containing polyatomic ions?

Writing Formula for Ionic Compounds The sum of the charges in any ionic compound must equal zero. We use subscripts to indicate the number of each ion in a compound. Example: barium chloride Ba Cl2 (2+) + [2(1-)] = 0

Covalent (Molecular) Compounds Covalent compounds form when electrons are shared between two non-metal atoms.

Naming Covalent Compounds When naming covalent compounds, we use prefixes to indicate the number of atoms of each element. Example: P2I4 diphosphorus tetraiodide