AtomsAtoms are the smallest units of an element that have the properties of that element.

ElementsElements are substances that cannot be broken down into simpler substances. They are the simplest substancessimplest substances.

Every substance in the universe is a combination of one or more elements.

ElementsElements

92 elements occur naturally on Earth; 23 have been created by scientists in laboratories.

•The elements and their symbols are shown on the PERIODIC TABLEPERIODIC TABLE

• How many elements are there?

PERIODIC PERIODIC TABLETABLE

listen to the “Element Song”

Elements are arranged on the Periodic Table:

Vertically into GroupsGroups

Horizontally Into PeriodsPeriods

Why?

If you looked at one atom of every element in a groupgroup you would

see…

Every atom in a group has the same number ofsame number of electronselectrons in its outermost in its outermost level.level.

For example…

The Group 2Group 2 atoms atoms all have 2 electrons2 electrons in their outer level

Be (Beryllium)

Atom

Mg (Magnesium) Atom

• The electrons in an atom’s outermost level are called the valencevalence electronselectrons.

• The number of valence electrons in an atom affects the way the atom bonds with other atoms.

• This is why elements in a group have similar properties– because they have the same number of valence electrons.

Electron Dot DiagramsElectron Dot Diagrams show the number of valence electrons in an atom.

Observe the electron dot diagrams of the Period 2 elements below.

What do you notice?

Electron Dot Electron Dot DiagramsDiagrams

Each group has distinct propertiesEach group has distinct properties• The Periodic Table is divided into groups

(vertical columns) based on the properties of each group’s elements.

Groups whose elements behave very similarly are called a familyfamily..

Soft, silvery-colored solids

Have 1 valence electron

Very reactive!!! especially with Halogens (Group 17)

video showing alkali metals mixing with water. Stand back…

Alkali Metals (Group 1)Alkali Metals (Group 1)

sodium reacting with water more Na + H2O

Lithium Sodium

Potassium

Rubidium Cesium

Alkali Metals

Francium

Alkaline Earth Metals Alkaline Earth Metals (Group 2) (Group 2)

Silvery-White Solids

Have 2 valence electrons

Fairly reactive

Many are found in rocks in the earth’s crust

CalciumMagnesium

Strontium

Beryllium

Barium Radium

Alkaline Earth Metals

Transition Metals Transition Metals Groups 3 to 12Groups 3 to 12

Malleable Malleable (easily hammered into sheets)

Most are good good conductors of conductors of electricityelectricity

DuctileDuctile (easily extruded into wire)• SolidsSolids (except for Mercury)

• High melting High melting pointspoints

• Shiny lusterShiny luster

Uses of Uses of Transition Transition

MetalsMetals

MetalloidsMetalloids

• share properties with both metals and non-metals

• Si (Silicon) and Ge (Germanium) are very important semi-conductors.

QuickTime™ and aTIFF (Uncompressed) decompressor

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• Semi-conductors are used in computer technology.

What are semiconductors used in?

NonmetalsNonmetals

Solids are brittle (break easily, don’t bend)

Do not conduct electricity

QuickTime™ and aTIFF (Uncompressed) decompressor

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Some are gases, some are solids, one is a liquid.

Non-Metals: Solids

Have 7 valence electrons

Reactive, especially with Alkali Alkali Metals (Group 1)Metals (Group 1)

Halogens (Group 17)Halogens (Group 17)

Exist as diatomic moleculesdiatomic molecules (F2, Cl2, Br2, I2), so that both atoms have a full outer electron layer.

Cl Cl

Remember:

BRINCLHOFBRINCLHOF

HalogensHalogens

• Fluorine is put into water supplies to kill harmful bacteria and to help keep teeth healthy.

• Chlorine is used in swimming pools to kill bacteria in the water.

• Bromine is used in pesticides. Silver bromide is used in photography.

• Iodine is used as an antiseptic on cuts, and as an indicator for starch.

Uses of the HalogensUses of the Halogens

Outer electron levels are full

Non-reactive (stable)

Gases at room temperature

Low melting & boiling points

Exist as single atoms rather than diatomic molecules (He, Ne, Ar, Kr, Xe, Rn)(He, Ne, Ar, Kr, Xe, Rn)

Noble Gases Noble Gases (Group 18)(Group 18)

HeliumHelium is lighter then air and is used in balloons and airships.

Jellyfish lamps made with noble gases artist- Eric Ehlenberger

Colors Noble Gases produce in lamp tubes:

• Ne (Neon):Ne (Neon): orange-redorange-red

• Hg (Mercury):Hg (Mercury): light bluelight blue

• Ar (Argon):Ar (Argon): purplepurple

• He (Helium):He (Helium): pale peachpale peach

• Kr (Krypton):Kr (Krypton): silvery-whitesilvery-white

• Xe (Xenon):Xe (Xenon): blue-greenblue-green

Actinide SeriesActinide SeriesLanthanide SeriesLanthanide Series

Both are silver, silvery-white, or gray metals. The metals have a high luster, but tarnish readily in air. The metals have high electrical conductivityhigh electrical conductivity. Many fluoresce under UV lightfluoresce under UV light.

LanthanidesLanthanides are relatively soft, have high melting and boiling points, burn in air, and are very reactive. Most are widely used in laserslasers.

ActinidesActinides are very dense radioactive metalsvery dense radioactive metals, which combine directly with most nonmetals.

Lanthanides & ActinidesLanthanides & Actinides

We are all carbon-based

life forms; carboncarbon is found in every living thing on Earth.

78% of the Earth’s

atmosphere is NitrogenNitrogen..

OxygenOxygen makes up 21% of Earth’s atmosphere, 47% of the Earth’s crust, and is found in 100% of all living things on Earth.

Really Important ElementsReally Important Elements

46.6% Oxygen (O)27.7% Silicon (Si) 8.1% Aluminum (Al) 5.0% Iron (Fe) 3.6% Calcium (Ca) 2.8% Sodium (Na) 2.6% Potassium (K) 2.1% Magnesium (Mg)

The 8 most common elements in Earth’s crust (by mass):

1. Oxygen (65%) 2. Carbon (18%) 3. Hydrogen (10%) 4. Nitrogen (3%) 5. Calcium (1.5%) 6. Phosphorus (1.0%) 7. Potassium (0.35%) 8. Sulfur (0.25%) 9. Sodium (0.15%) 10. Magnesium (0.05%)

Hydrogen Nitrogen

Top 10 elements in the human body

BismuthBismuth MercuryMercury

the only metal that is liquid at STP

Some Cool ElementsSome Cool Elements

Gold Silver

Platinum

Elements used in jewelry

Dmitri MendeleevDmitri Mendeleev (1834 - 1907) organized the 63 (1834 - 1907) organized the 63 elements that were known at that time (1869) elements that were known at that time (1869) into the Periodic Table. He predicted the into the Periodic Table. He predicted the existence of 3 elements that had not yet been existence of 3 elements that had not yet been discovered, based on the gaps in his periodic discovered, based on the gaps in his periodic table. The 3 elements were discovered later table. The 3 elements were discovered later (scandium, gallium, germanium).(scandium, gallium, germanium).

Mendeleev’s Periodic TableMendeleev’s Periodic Table

Early versions Early versions of Mendeleev’s of Mendeleev’s

tabletable

Glenn Glenn SeaborgSeaborg(1912-(1912-1999)1999)

• Discovered 8 Discovered 8 new elementsnew elements

• Only living Only living person for person for whom an whom an element was element was named (named (Sg, Sg, seaborgiumseaborgium, , element 106)element 106)

RutherfordRutherford

BohrBohr

MeitnerMeitner

RoentgenRoentgen

CurieCurie

EinsteinEinstein

FermiFermi

MendeleevMendeleev

Other scientists who have had elements named after them…