Periodic Table

The Periodic Law Elements are arranged by increasing atomic number What is atomic number? Period – A row in the table of elements Varies in number of available orbitals (this will make sense later) Group – A column in the periodic table Elements within a group have similar properties Periodic Law – Patterns of repeating properties The Periodic Law

All Periodic Tables usually contain: 4 pieces of information: Name of the Element Symbol of the Element Atomic Number Atomic Mass – Average distribution of naturally occurring masses and their isotopes Atomic Mass

Classes of Elements Metals Transition Metals Nonmetals Metalloids Good conductors of electricity and heat Most are malleable, ductile, solid at room temperature (except for mercury) Transition Metals Able to form compounds with distinctive colors Iron or chromium can make glass green Copper or gold can make glass red Cobalt makes glass blue Nonmetals Poor conductors of heat and electricity Low boiling points, some are gases at room temperature, brittle (if solid at room temp) Metalloids Have properties that fall between those of metals and nonmetals Properties become LESS METALLIC AND MORE METALLIC across a period Classes of Elements

Valence Electrons – an electron that is in the highest occupied energy level of an atom Play a key role in chemical reactions Valence electrons INCREASE across a period Elements in a group have similar properties because they have the same number of valence electrons Valence Electrons

Alkali Metals Look at your Periodic Table Group 1 Called ALKALI METALS Have 1 valance electron Extremely reactive Found in nature only in compounds Example Table Salt – Sodium Chloride - NaCl Alkali Metals

Alkaline Earth Metals Group 2 Called ALKALINE EARTH METALS Have 2 valance electrons Very reactive Reacts with water Example Calcium have essential biological functions (Calcium Carbonate CaCO3) Alkaline Earth Metals

The Boron Family Group 3 Called the Boron Family Have 3 valance electrons Contains metals and metalloids Example A compound of boron, silicon, and oxygen is used to make a type of glass that does not shatter easily when it undergoes a rapid change in temperature The Boron Family

The Carbon Family Group 4 Called the Carbon Family Have 4 valance electrons Contains nonmetals, metals, and metalloids Example Silicon carbide – used to tip saw blades, making them last longer than steel blades The Carbon Family

The Nitrogen Family Group 5 Called the Nitrogen Family Have 5 valance electrons Contains nonmetals, metals, and metalloids Example Red phosphorus is used on match tips to ignite them. The Nitrogen Family

The Oxygen Family Group 6 Called the Oxygen Family Have 6 valance electrons Contains nonmetals and metalloids Example Sulfuric acid is used to make fertilizers The Oxygen Family

The Halogens Group 7 Called the Halogens Have 7 valance electrons Contains nonmetals Example Fluorine is used to prevent tooth decay The Halogens

The Noble Gases Group 8 Called the Noble Gases Have 8 valance electrons Contains nonmetals Example Used in neon signs Helium – pink Neon – orange/red Argon – purple Krypton – white Xenon - Blue The Noble Gases

Octet Rule – The tendency for all elements to want to have EIGHT electrons by gaining or losing electrons and forming ions Ion – An atom or group of atoms that has a positive or negative charge Octet Rule

Practice How many valence electrons are in the following elements? Si Selenium I Astatine Rn Barium Fr Tl Lead Antimony Practice