Periodic Table of Periodic Table of ElementsElements

4.14.1

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Dmitri MenveleevDmitri MenveleevIn the last century, a scientist named In the last century, a scientist named

Dmitri MendeleevDmitri Mendeleev looked for ways to looked for ways to organize the current knowledge about organize the current knowledge about newly discovered elements and their newly discovered elements and their atoms. atoms.

He invented a periodic table – an He invented a periodic table – an organized arrangement of elements that organized arrangement of elements that explained and predicted physical and explained and predicted physical and chemical properties. chemical properties.

Mendeleev’s table was key to Mendeleev’s table was key to understanding elements and discovering understanding elements and discovering new elements and compounds.new elements and compounds.

Initially, Mendeleev organized elements Initially, Mendeleev organized elements based on their based on their atomic massatomic mass (average (average weight of the atoms in the element).weight of the atoms in the element).

He found that this did not always work.He found that this did not always work.So he decided to group elements based So he decided to group elements based

on their on their atomic numberatomic number (the number (the number of protons in the nucleus) instead.of protons in the nucleus) instead.

Using the periodic table, Mendeleev Using the periodic table, Mendeleev was able to actually predict the was able to actually predict the existance of certain elements even existance of certain elements even before they were discovered!before they were discovered!

Ex. Gallium was predicted in 1871 and Ex. Gallium was predicted in 1871 and not actually discovered until 1875.not actually discovered until 1875.

Mendeleev’s decision to use the Mendeleev’s decision to use the atomic number rather than atomic atomic number rather than atomic mass proved to be a good one. When mass proved to be a good one. When subatomic particles (protons, subatomic particles (protons, neutrons, and electrons) were later neutrons, and electrons) were later discovered, it became clear that the discovered, it became clear that the atomic number (number of protons in atomic number (number of protons in the nucleus) held the key to the the nucleus) held the key to the identity of an element.identity of an element.

Groups of ElementsGroups of Elements

The periodic table groups elements The periodic table groups elements with similar properties. You can with similar properties. You can quickly identify an element as a quickly identify an element as a metal if it is on the left or in the metal if it is on the left or in the centre of the table.centre of the table.

Non-metals are generally found on the Non-metals are generally found on the right side.right side.

Chemical GroupsChemical Groups

The set of elements in the same The set of elements in the same column in the table is called a column in the table is called a chemical groupchemical group (having similar (having similar chemical and physical properties). chemical and physical properties).

These properties, however, vary from These properties, however, vary from element to element in a column.element to element in a column.

PeriodsPeriods

The horizontal rows of elements are The horizontal rows of elements are called called periodsperiods. The first period . The first period contains two elements: hydrogen contains two elements: hydrogen and helium.and helium.

As you go from left to right within a As you go from left to right within a row, the atomic number increases row, the atomic number increases and the elements gradually change and the elements gradually change from from metallicmetallic (lithium)(lithium) to to non-non-metallicmetallic (flourine), and then finally to (flourine), and then finally to noble gasesnoble gases (neon) at the far right. (neon) at the far right.

REPRESENTATIVE REPRESENTATIVE ELEMENTSELEMENTS

Are the elements in Groups 1,2 and 13-Are the elements in Groups 1,2 and 13-1818

Of all the elements, the representative Of all the elements, the representative elements best follow the periodic law.elements best follow the periodic law.

The laws and theories presented in The laws and theories presented in introductory chemistry courses are introductory chemistry courses are often restricted to these elements.often restricted to these elements.

TRANSITION ELEMENTSTRANSITION ELEMENTS

Are elements in Groups 3 to 12.Are elements in Groups 3 to 12. These elements exhibit a wide range These elements exhibit a wide range

of chemical and physical properties.of chemical and physical properties.

Today, the modern periodic law states:Today, the modern periodic law states:

If the elements are arranged according If the elements are arranged according to their atomic number, a pattern can to their atomic number, a pattern can be seen in which similar properties be seen in which similar properties occur regularly.occur regularly.

Hand out tables and colour groups to Hand out tables and colour groups to match the table at the back of the match the table at the back of the book.book.

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AssignmentAssignmentRefer to your periodic table as the class Refer to your periodic table as the class

reads pages 110-113 in the text.reads pages 110-113 in the text.

Use a colour code and colour your in Use a colour code and colour your in the following sections on your the following sections on your periodic table:periodic table:

1.1. Group of One - GreenGroup of One - Green

2.2. Alkali Metals – BlueAlkali Metals – Blue

3.3. Alkali Earth Metals – RedAlkali Earth Metals – Red

4.4. Transition Metals - YellowTransition Metals - Yellow

5.5. Metalloids – Dark PurpleMetalloids – Dark Purple

6.6. Halogens – Light PurpleHalogens – Light Purple

7.7. Noble Gas - OrangeNoble Gas - Orange

Group of OneGroup of One

Hydrogen is a unique element (Hydrogen is a unique element (GreenGreen).). It’s most common isotope has only a It’s most common isotope has only a

single proton and no neutron in its single proton and no neutron in its nucleus.nucleus.

Hydrogen doesn’t have much in common Hydrogen doesn’t have much in common with the alkali metals. It’s a colorless, with the alkali metals. It’s a colorless, odorless, tasteless, highly flammable gas.odorless, tasteless, highly flammable gas.

Almost all of Earth’s hydrogen exists in Almost all of Earth’s hydrogen exists in combination with other elements. Its combination with other elements. Its reactivity is too great for it to exist in the reactivity is too great for it to exist in the atmosphere as a free element. atmosphere as a free element.

Alkali MetalsAlkali Metals

Occupy the far left column of the Occupy the far left column of the periodic table (periodic table (blueblue).).

Extremely reactive.Extremely reactive. Found in nature only as compounds, Found in nature only as compounds,

and are found everywhere on Earth.and are found everywhere on Earth. Most common are sodium Most common are sodium

compounds, which occur in plants, compounds, which occur in plants, animals, soil and sea water.animals, soil and sea water.

Lithium, sodium, potassuim, etc…Lithium, sodium, potassuim, etc…shiny, silvery.shiny, silvery.

Alkali Earth MetalsAlkali Earth Metals

Occupy the second to the left column Occupy the second to the left column of the periodic table (of the periodic table (redred).).

They are light, reactive metals that They are light, reactive metals that form oxide coatings when exposed to form oxide coatings when exposed to air.air.

Often insoluble in waterOften insoluble in water Also shiny, silver metalsAlso shiny, silver metals Beryllium, calcium, magnesium, Beryllium, calcium, magnesium,

bariumbarium

MetalloidsMetalloids

The staircase (The staircase (purplepurple)) Elements that possess both metallic Elements that possess both metallic

and non-metallic properties. Found and non-metallic properties. Found on both sides of the zigzag line that on both sides of the zigzag line that divides the metals from the non-divides the metals from the non-metals.metals.

Ex. silicon, boron, germanium, Ex. silicon, boron, germanium, arsenic, selenium, antimony, arsenic, selenium, antimony, tellurium, polonium, and astatine.tellurium, polonium, and astatine.

HalogensHalogens

Occupy the 17Occupy the 17thth column of the column of the periodic table (fluorine, chlorine, periodic table (fluorine, chlorine, bromine…) (bromine…) (light purplelight purple))

Most reactive non-metals.Most reactive non-metals. Because of their reactivity, they Because of their reactivity, they

almost always appear naturally as almost always appear naturally as compounds, not as elements.compounds, not as elements.

Most common halogen compounds Most common halogen compounds are chlorine compounds found in are chlorine compounds found in living things, ocean water and rocks.living things, ocean water and rocks.

Noble GasesNoble Gases

Occupy the far right column of the Occupy the far right column of the periodic table (periodic table (orangeorange).).

All gases at room temperature, the All gases at room temperature, the noble gases are often called inert noble gases are often called inert gases because they are so unreactive, gases because they are so unreactive, almost never forming chemical almost never forming chemical compounds with other elements.compounds with other elements.

Argon makes up 1% of every breath Argon makes up 1% of every breath you inhale.you inhale.

Very useful elements. Ex.: neon, Very useful elements. Ex.: neon, heliumhelium