CHEMISTRY!

Chemistry - Video Chemistry – The study of matter and changes in matter Matter – Anything that has a mass and occupies space

Compounds – Two or more elements combined. Ex: H2O or NaCl

Element – Pure substance made from one sort of atom. Ex: H or O

Atom – The smallest unit of matter

Five parts to an atom: Nucleus – the centre of the atom – contains neutrons and protons. protons – Positive charge (+) neutrons – No charge or neutral (0) electrons – Negative charge (-) Electron shell – the region around the nucleus where the electrons are found.

The Periodic Table

Pre-Periodic Table Chemistry … …was a mess!!! No organization of elements. Difficult to find information. Chemistry didn’t make sense.

Dmitri Mendeleev Father of the Periodic Table WHAT HE DID… Put elements in rows by increasing atomic weight Put elements in columns by the way they reacted. SOME PROBLEMS… He left blank spaces for what he said were undiscovered elements. He broke some patterns

A: Atomic number = number of protons B: The elements charge C: The elements symbol D: The name of the element E: Atomic Mass or the number of protons and neutrons

Atomic number - # of protons Atomic Mass – Mass of protons and neutrons So… how do you calculate the number of neutrons? Atomic Mass – Atomic number = # of neutrons! Number of Electrons equals the number of protons in a neutral atom.

Notes – Chemistry Introduction Sheet to complete: Atomic Structure Worksheet

The Periodic Table

A: Atomic number = number of protons B: The elements charge C: The elements symbol D: The name of the element E: Atomic Mass or the number of protons and neutrons

The Periodic Table Groups Periods

Period: indicates the number of shells of an element

Group/family: indicates the number of electrons on the valence shell

Group 1 – Alkaline metals The most reactive group of elements Reactivity increases as you move down the group Cs and Fr are liquids; all others are solid

Group 2 - Alkaline Earth Metals Reactive but not as reactive as the Alkaline metals Several of these elements are important mineral nutrients (such as Mg and Ca) All are solids

Group 3 – 12 – Transition Metals Less reactive metals Not as predictable as other metals Have a wide variety of properties Hg is the only liquid; all others are solid

Group 17 - Halogens Very reactive nonmetals Fluorine is the most reactive this decreases as you move down the group F and Cl are gas; Br is liquid; I and At are solid

Group 18 – Noble Gases Extremely low chemical reactivity or inert (very stable) Used in common items such as neon signs or balloons All are gas

Lanthanides & Actinides Lanthanides: atomic numbers 57 – 71 (top row) Actinides: atomic numbers 89 – 103 (bottom row) All solid

Metals, Nonmetals, and Metalloids 6.1 Metals, Nonmetals, and Metalloids

Metals To the left of the staircase line Physical Properties: Luster (shiny) Good conductors High melting point Solids at room temperature (mercury is an exception) Chemical Properties: Easily lose electrons Corrode easily (rusting or tarnishing)

Non-metals to the right of the staircase line Chemical Properties: Tend to gain electrons Physical Properties: Dull (not shiny) Poor conductor of electricity Brittle Low Melting Point

Metalloids along the staircase line Solids Shiny or dull Conduct heat and electricity better than non metal but not as well as metals

Notes – The Periodic Table Sheet to complete: The periodic table

Electron Shell Diagram (Bohr-Rutherford) Period: Indicates the number of shells or energy levels of the element

Electron Shell Diagrams – Bohr-Rutherford

Electron Dot Diagram (Lewis Diagram) Group/family: indicates the number of electrons in the outer shell (valence shell)

Practice! Electron Dot Diagram – Lewis diagram

Electrons on the Move! The goal of every atom is to become stable like the Noble Gases. There are three ways this can be accomplished: Lose electrons Gain electrons Share electrons

Remember Valence Electrons? What are they? Electrons on the last shell or energy level of the atom How many valence electrons around each of these elements? Na S Br Ne

Ions Ions are an atom or a group of atoms that have a positive or negative charge. An ion is formed when atoms lose or gain electrons There are two types: Cation – a positively charged atom caused by a neutral atom losing one or more electrons Anion: a negatively charged atom caused by a neutral atom gaining one or several electrons.

Metals form cations because they lose electrons easily Metals form cations because they lose electrons easily. Therefore their charge is positive. How many electrons will the following metals lose? Na Mg B Non metals form anions because they gain electrons. Therefore their charge is negative. How many electrons will the following non-metals gain? N O F Ne After losing or gaining electrons, their valence shell is full and therefore stable.

Ex: N is a non-metal and in group 15, therefore it has to gain 3 electrons to become the anion N3- . Ex: O is a non-metal in group 16, therefore it has to gain 2 electrons to become stable. It will become the anion O2- . Ex: Na is a metal in group 1, therefore it has to lose 1 electron to become stable. It will become the cation Na+.

To Do: Animation: What are ions? Notes: Ions Practice Sheets Ions Sheet Review Electrons on the move