Organizing the Elements The Periodic Table

Elements There are 118 different kinds of atoms. Most matter is made up of two or more kinds of atoms, but some consist of just one type of atom. When matter is composed of one type of atom it is called an element. 94 elements are naturally occurring and the remaining are synthetic or unstable elements (24)

Elements Single atom of oxygen Molecule of oxygen

Element… Element: An element is a pure substance that cannot be broken down into a simpler chemical substance by any physical or chemical means Ex. Gold, copper, carbon, lead

Representing Elements… Element Symbol: An abbreviation for a chemical element. The symbols for elements are the same all over the world, regardless of the language. The symbol of an element is taken from its name. Often the first letter is used. (Fluorine = F)

Element symbols.. ElementSymbol OxygenO CarbonC NitrogenN

The name of an element may begin with the letter of a symbol already in use. So they are named by: The element’s first two letters, Os, for Osmium The first letter and some other letter in the name, Cl, for Chlorine Symbols are taken from their Greek or Latin names, Aurium for gold Symbols are sometimes named after famous scientists or places eg. Einsteinium or Americium

ElementSymbol HeliumHe Lead (plumbum)Pb CalciumCa Gold (aurium)Au Copper (cuprum)Cu EuropiumEu Curium (Marie Curie)Cm

Rules for writing symbols: The symbol always begins with a capital letter If there is a second or third letter, it is always a lowercase letter There is no period at the end of the symbol

Early Classification of Elements… Alphabetical, colour, taste didn’t work Metals vs. non-metals These just didn’t seem to cut it….

Mendeleev Russian chemist Organized 64 elements known at that time He did it by atomic mass Found similarities in physical properties of those in the same columns

Today’s Table Periodic table: a table in which the elements are organized into rows and columns according to their atomic numbers and properties

Today’s Table Primarily organized by; 1.atomic number, 2.metal/non-metal 3.properties like reactivity Organized into groups/families and periods

The periodic Table of Elements… MbII0

Metals, metalloids, Non- metals

Metals Metals: an element that is lustrous, malleable, ductile and conducts heat and electricity Even if the metal appears to be dull in colour on the surface, freshly cut a metallic sheen can be seen Located on the left side of the periodic table

Non-metals Non-metals: an element usually a gas or dull powdery solid that does not conduct heat or electricity. Upper right portion of the periodic table Bromine is the only liquid non-metal at room temperature

Metalloids Metalloids: an element that has properties of both a metal and a non-metal. Found along the staircase line between metals and non-metals

Periods (there are 7) Each row represents a separate period Have the same number of electron shells (energy levels)

Groups (there are 18) Arranged together in rows (numbered 1 to 18) Also called a family All elements in each group have similar properties

Group 1: Alkali Metals React rapidly when exposed to air and water Shiny, silvery and soft Highly reactive, often explosive in water

Group 2: Alkaline Earth Metals Be, Mg, Ca, Sr, Ba, Ra Shiny and silvery, but not soft Less reactive than alkali metals These metals have a distinguishable flame color, Mg & Be white, brick-red for Ca, magenta-red for Sr, green for Ba and crimson red for Ra.

Group 3-12:Transition Metal Includes Ga, In, Sn, Tl, Pb, Bi, Lu, Lr and all the Uu… metals Low reactivity Rare earth metals/ inner transition metals often included

Group 18: Noble Gases Unreactive, colourless, odourless All gases (He, Ne, Ar, Kr, Xe, Rn) He- low density for balloons, Used for neon signs(glow with electric current) –Ar: blue, Kr: pink/white, Xe: purple, Ne:red 1whUQ

Group 17: Halogens Most reactive non-metals Rarely found in elemental form Poisonous in large amounts Many common uses: –Chlorine: pools –Iodine: clean wounds –Bromine: halogen light bulbs

Hydrogen? As you may have noticed hydrogen is not classified with any other group Hydrogen is unique in the sense that it has a single electron in the first orbital Hydrogen can donate an electron like the alkali metals but can accept an electron like a halogen Non-metal

Periodic Trends We saw changing reactivity between groups – Group 1 more reactive than group 2 –Group 17 more reactive than group 16 in the same row Other trends:

Other trends As you go down a family, the number of electron orbits increases Within a family all elements have the same # of electrons in the outer most shell Reactivity is based on the number of electrons in the outer shell

Most reactive groups

GROUP # VALENCE ELECTRONS GAIN/LOSE to be STABLE Overall Charge of ion Metal/Non- metal Group 11Lose 1 electron1+ chargemetal Group 22 Lose 2 electrons 2+metal Group 133 Lose 3 electrons 3+metal Group 144 Gain or lose 4 electrons 4+ or 4-Non-metal Group 155Gain 33-Non-metal Group 166Gain 22-Non-metal Group 177Gain 11-Non-metal Group 182 or 8NOT REACTIVE NO CHARGENon-metal