CHAPTER 12: Periodic Table

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Early 1860’s• Scientists knew some of the properties of more

than 60 elements that existed.• BUT…..they were not in any order.

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Demitri Mendeleev 1869 • Mendeleev was the first scientist to

write the names and properties of each element on the an index card.

• He used properties such as; density, appearance, and melting point.

• He then arranged the elements in order of increasing atomic mass.

• Mendeleev discovered a repeating pattern that took place among the elements going from left to right across and up and down.

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Demitri Mendeleev 1869 • Periodic – means happening at regular intervals,

“repeating”.• Example – the days of the week.

• He left spaces or question marks for unknown or undiscovered elements.

• Mendeleev’s arrangement of elements became known as the periodic table of elements.

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Henry Moseley 1914

• Moseley – a British scientist, determined the atomic number (# of protons) in an atom.

• Periodic Table is also arranged by increasing atomic number or by increasing number of protons.

• Periodic Law – the repeating chemical and physical properties of elements change periodically with the element’s atomic numbers.

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Periodic Table• A periodic table is an arrangement of elements in

columns, based on a set of properties that repeat from row to row. (page 338-339)

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• Periods are the rows in the periodic table (horizontal).• Elements change from metals to nonmetals as you move

from left to right across the period.• Groups/Families are the columns on the periodic table.

(vertical) • Properties of elements repeat in a predictable way.

(Periodic Law)

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Period ------------Period ------------Period ------------Period ------------

Gro

up

--G

rou

p --

Gro

up

--G

rou

p --

Classes of elements• Elements are classified as metals, metalloids, and

nonmetals based on their properties.1. Metals – Start at the far left hand side and stop at the

zigzag line.• - Most elements are metals.• - Most are solids at room temperature.• - The exception: Mercury (Hg)• - Metals tend to be shiny, luster.• - Malleable – hammered into thin sheets.• - Good conductors of electricity/heat.• - Ductile – made into thin wires. 8

Classes of elements2. Nonmetals – Start at the far right hand side and stop at

the zigzag line.• - More than half are gases at room temperature.• - Nonmetals tend to be dull, lack luster.• - Brittle –will shatter if struck with a hard object.• - Poor conductors of electricity/heat - insulator• - Non-ductile – cannot be drawn into wires.

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Classes of elements3. Metalloids – elements that border the zigzag line.• - Tend to have properties that are in between

metals and nonmetals.• - Called semiconductors

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Tellurium is shiny, but it is brittle and can easily be smashed into a powder.

Boron is very brittle. At high temperatures it is a good conductor of electricity/heat.

Valence Electrons•A Valence Electron is an electron that is in the highest occupied energy level of an atom.•Elements in a group have similar properties because they have the same number of valence electrons.

Group Valence Electrons

1A 1

2A 2

3A 3

4A 4

5A 5

6A 6

7A 711

Alkali Metals family•Group 1•Most reactive metals

• Reactivity increases from the top to the bottom.

• Francium is the most reactive metal!

• So reactive many are kept under oil to prevent reacting with water or oxygen.

• Found in nature only in a compound.

• One Valence Electron• Give away one valence electron

and form +1 ion in order to become stable.

Element Symbol

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Lithium Li

Sodium Na

Potassium K

Rubidium Rb

Cesium Cs

Francium Fr12

Alkaline Earth Metals FamilyElement Symbol

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Beryllium Be

Magnesium Mg

Calcium Ca

Strontium Sr

Barium Ba

Radium Ra

•Group 2•2 Valence Electrons•Give away 2 valence electrons and form +2 Ions in order to become stable.•Less reactive than group 1.•Magnesium used in photosynthesis.•Calcium used in teeth and bone.

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Transition Metals•Groups 3 – 12•1 or 2 valence electrons•Less reactive than alkaline earth metals•Shiny, good conductors of heat and electricity.•Their properties vary widely.

14Many are solids at room temp, except Mercury.

Many are silver in color except Gold.

Titanium not very reactive.

Iron is very reactive and can react with oxygen in the air to form rust.

Transition MetalsLanthanides and Actinides

•Transition metals from periods 6 and 7.

•Lanthanides are shiny reactive metals.• - Some of these elements are used to make steel.•Actinides are radioactive, or unstable. • - Elements listed after Plutonium, element 94 do not occur naturally in nature.

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Boron Family•Group 13•3 Valence electrons•Give away 3 valence electrons and form +3 ions in order to become stable.•1 metalloid (Boron)•Five metals•Aluminum is the most abundant metal in the Earth’s crust.

Element Symbol

Hyperlink

Boron B

Aluminum Al

Gallium Ga

Indium In

Thallium Tl

Ununtrium Uut16

Carbon Family•Group 14•4 Valence Electrons•Can give away 4 or take 4 valence electrons and form +/- 4 Ions in order to become stable.•1 Nonmetal•2 Metalloids•3 Metals•With the exception of water, most of the compounds in your body contain carbon.

Element Symbol

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Carbon C

Silicon Si

Germanium Ge

Tin Sn

Lead Pb

Ununquadium

Uuq17

Nitrogen FamilyElement Symbol

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Nitrogen N

Phosphorus P

Arsenic As

Antimony Sb

Bismuth Bi

Ununpentium Uup

•Group 15•5 Valence Electrons•Take 3 valence electrons and form -3 Ions in order to become stable.•2 nonmetals•2 metalloids•2 Metals•Nitrogen and Phosphorus are used in fertilizers.

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Oxygen FamilyElement Symbol

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Oxygen O

Sulfur S

Selenium Se

Tellurium Te

Polonium Po

Ununhexium Uuh

•Group 16•6 Valence Electrons•Take 2 valence electrons and forms -2 Ions in order to become stable.•3 nonmetals•1 metalloid•2 metal•Oxygen is the most abundant element in the Earth’s Crust.

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Halogen FamilyElement Symbol

Hyperlink

Fluorine F

Chlorine Cl

Bromine Br

Iodine I

Astatine At

Ununspetium Uus

•Group 17•7 Valence electrons•Take 1 valence electron and form -1 Ions in order to become stable.•Most reactive nonmetals•Reactivity increases from bottom to top.•Fluorine is the most reactive nonmetal.

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Noble Gas Family•Group 18•8 Valence Electrons•Un-reactive (Do not form Ions) because they are stable.•The Noble Gases are odorless and colorless.•Used in light bulbs (Argon).•Make balloons float (Helium).•Used to make neon lights.

Element Symbol

Hyperlink

Helium He

Neon Ne

Argon Ar

Krypton Kr

Xenon Xe

Radon Rn

Ununoctium Uuo 21