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Periodic Trends  Chemistry Periodic Trends  Chemistry

Periodic Trends Chemistry - PowerPoint Presentation

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Periodic Trends Chemistry - PPT Presentation

Classification of Elements 1829 German Chemist JW Dobereiner published a classification system to sort elements Noted trends and patterns related to chemical properties Classified the elements into TRIADSsets of three elements of similar properties ID: 738235

group elements energy electrons elements group electrons energy metals amp atomic properties periodic element electron reactive valence metal ionization

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Slide1

Periodic Trends ChemistrySlide2

Classification of Elements1829 German Chemist J.W. Dobereiner published a classification system to sort elements

Noted trends and patterns related to chemical properties

Classified the elements into TRIADS(sets of three elements of similar propertiesSlide3

1st Periodic Table

1871

Dmitri Mendeleev- a Russian chemist who arranged elements in order of their increasing atomic massesSlide4

Modern Periodic TableHenry G.J.Moseley

Father of Modern Periodic Table

1913 British Physicists

determined the atomic number for each known element

Arranged the periodic table according to increasing atomic numbersSlide5

ROWS= PERIODS OR SERIESAdjacent elements in each horizontal row(period) differ in both chemical and physical properties but the properties change in a regular way across each periodSlide6

COLUMNS= GROUPS OR FAMILIESProperties of elements in any vertical column do differ. They are similar but not identical in chemical behavior.Why do elements in a group have similar properties?

Similar electron arrangementsSlide7

IUPAC International

U

nion of

P

ure and

A

pplied

C

hemistry –the organization that sets standards for chemistry1985 proposed a new system for labeling periodic table.

Groups 1-18 labeled in black from left to right

Used in U.S. and Europe

Divided into metals, nonmetals and metalloidsSlide8

METALS80% of elements

PROPERTIES OF METALS

DUCTILE-can be drawn into wires

HIGH LUSTER

MALLEABLE- can be hammered or rolled into sheets

GOOD CONDUCTORS of heat & electricity

METALLIC BONDING-electrons are layered and the outer layers are weakly heldSlide9

METALLIC BONDINGA type of bonding that is neither ionic nor covalentThe outermost electrons wander freely through the metalSlide10

NonMetalsMost are gaseous at room temperature

Some are solid and one is liquid(Bromine)

Dull

Brittle and powdery

Poor conductors of heat and electricity

Not malleable or ductile

Generally have low melting points

H, C, N, P, As(Arsenic), O, S, Se(Selenium), & Group 17 & 18.Slide11

METALLOIDSProperties of both metals and nonmetalsDepending on the conditionsMost are semiconductors-a substance that can conduct electricity under given conditions

Used to make computer chipsSlide12

Structure of Periodic TableDisplays symbols and names of the elements and infoElements are sorted based on their electron configuration and location on table

Noble gases

R

epresentative elements

Group B Elements

Transition metals

Inner transition metalsSlide13

While atoms of different elements have different numbers of electrons, they may have the same number of electrons in their outer energy levelsSlide14

Electron Configurations in GroupsNoble gases- inert gases

Group 18 or 8A

s & p

energy levels

filled

Orginally

called noble because they did not “mix” with common “folk” or other elements. However some compound have been made in laboratory settings

.

Inert=rarely take place in chemical reactions

Contain 8 electrons in their outer most energy level and are therefore very stable.

Used in “Neon” signs and laser shows.Slide15

Electron Configurations in GroupsRepresentative ElementsGroups 1A-7A ( 1,2, 13,14,15,16,17)

Wide range of physical and chemical properties

Metals, Nonmetals, & Metalloids

Solids-Bromine only liquid

s & p

of highest energy levels

not filled

Group number equals valence electronsSlide16

HYDROGEN-Group 1A(nonmetal) H

2

= DIATOMIC MOLECULE

90 % of all atoms in the universe are Hydrogen

Found in foods, and water and account for 60% of body mass

Reactive(

ie

. H2 burns in oxygen to form H

2O)Hydrogen will share e’ with NONMETALS or

Hydrogen will gain an e’ from METALSSlide17

Group 1A-Alkali MetalsArabic word

al

aqali

= the ashes

Wood ashes are high in Na and K

Highly reactive and found naturally only in compounds

One valence electronSlide18

Group 2A- Alkaline Earth MetalsLithium Compounds are used to treat bipolar disordersLithium is used in rechargeable batteries

Francium- radioactive and extremely rare( only 25-30 g can be found in the Earths crust at one time)

Sodium-hard as butter and can be cut w/ a knife. Can float in water

NaCl

-table salt-obtained from evaporation of seawater or from

lg

salt deposits on the surface of Earth or underground

Essential dietary salt

Potassium- stored in oil because will react violently with water vapor and oxygen in air

Cesium must be kept in sealed glass tube containing argon gas.Slide19

Group 2A-Alkaline Earth MetalsContain two valence electronsHighly reactive

Found in nature in compounds

Calcium

Body needs for strong bones and teeth

Calcium Carbonate-chalk, limestone, coral, and pearls.

Toothpaste may contain Calcium carbonate to help polish teeth

Plaster cast contains calcium sulfate Slide20

Group 2A-Alkaline Earth MetalsMagnesiumKey role in photosynthesis-found in chlorophyll molecules

Used in alloys-strong as steel yet lighter

Cars, bicycles, and backpacks

Used to produce bright white color in fireworks

Old flash bulbs of cameras

Strontium

Used to produce bright red color

in fireworks

Barium compounds

used to diagnose some digestive disorders

Radium

radioactive and once used to treat cancers

Beryllium

lightweight, strong, hard metal that is easy to shape

used in nuclear weapons and reactors.Slide21

MIXED GROUPS Groups 13-16Vertical groups that contain combinations of METALS, NONMETALS, AND METALLOIDS.Named for the first element of the family/group.Slide22

BORON GROUP Group 3A Boron-(METALLOID) Boric Acid used to kill insects & make polymers like slime, Borax used to whiten clothes.

Aluminum(METAL)-cans, foil, etc

Gallium, Indium, and Thallium(METALS) are used to produce semiconductors(conduct electric current under certain conditions)Slide23

CARBON GROUP Group 4A

Carbon

Contains

four electrons in outer energy level

VERY VERSITILE

2

ND

common element in bodyNonmetal Allotropes-different forms of the same element having different molecular structures.

Graphite(hexagonal) carbon bonded w/3 other carbons

Silicon,

Germainum

(METALLOID) also used to produce semiconductors

Tin

(METAL)-typical properties

Lead-

(typical METAL)-too much in bloodstream can lead to organ damage

especially

in yo

ung children.Slide24

ALLOTROPES OF CARBONDiamond STRUCTURE

GRAPHITE STRUCTURE

(tetrahedron)carbon bonded w/ 4 other carbons

(hexagonal) carbon bonded w/3 other carbonsSlide25

NITROGEN GROUP Group 5AContain 5 valence electrons(covalent)

Nitrogen

-NONMETAL; diatomic molecule N2

80% of every breath

4

th

element in abundance in body

Phosphorus =NONMETAL

Arsenic & Antimony=METALLOIDS

Bismuth

=METALSlide26

OXYGEN GROUP Group 6A Contains 6 valence electrons

Oxygen –NONMETAL, diatomic molecule O2

20% of air

O3-ozone molecule; an allotrope of O2

What is the benefit of ozone?

Sulfur & Selenium-NONMETALS

Selenium is used in dandruff shampoos

Tellurium & Polonium-METALLOIDS

Polonium is most toxic element knownSlide27

HALOGENS Group 7A Salt Formers-produce “salts”

Halogens have seven(7) electrons in their outer energy level

If an halogen gains and electron from a metal(ionic) a salt is formed

When in gaseous state they form diatomic(covalent)molecules and give distinctive colors.

Fluorine

is the most chemically reactive

Iodine

is a grey solid at room temperature that is obtained from brine. When heated it changes directly into a purple vapor without forming a liquid(sublimation). What role does iodine play in the body?

Bromine

-used in some cosmetic dyes.Slide28

Electron Configurations in GroupsGroup B Elements

Classified according to electron configurations

Transition Metals

Inner Transition Metals

Transition Metals

Highest

s

sublevel and nearest

d sublevel contain electrons

Inner Transition Metals

f

orbitals

contain

electrons, contain 1 or 2 valence electrons

Once thought to be rare earth metals now known to be most abundant

Lanthanoid

Series(Elements #57-71)

Actinoid

Series( Elements # 89-103)

Transuranium

Elements(#93-118) are all synthetic. Slide29

Transition Elements

IRON TRIAD

Iron, Cobalt, & Nickel

First elements of groups 8,9, &10

They have magnetic properties

All three are used to create steel and other metal mixtures

Nickel is added to steel for strength & shiny protective coating to other metals

Iron is the 2

nd

most abundant in Earth crust

CoINAGE

METALS

Copper, silver, & gold

First three members of Group 11

Stable, very malleable and ductile

Found in elemental form in nature

Used to make coins and jewelry

Copper is used in electrical wiring

Silver Iodide and Silver bromide are used in photography paper Slide30

Zinc, Cadmium, & MercuryFirst three elements of group 12Zinc and Cadmium are used to electroplate other metals

Cadmium

is used in rechargeable batteries (Ni-

Cd

)

Mercury- silvery liquid metal at room temperature.

Used in thermometers, thermostats, switches, and batteries. Poisonous and accumulates in the body.Slide31

SYNTHETIC ELEMENTS Periods 6 & 7Synthetic elements are those created in laboratory settings or “synthesized”

There are

24

synthetic elements-12 of which are in the

Lanthanoid

&

Actinoid SeriesSlide32

Synthetic Elements cont’d

Lanthanoid

Series

(Elements #57-71)

Promethium-used to power pacemakers and artificial hearts

Actinoid

Series

( Elements # 89-103)

Americium-found in smoke detectors

Transuranium

Elements(#93-118) are all synthetic. These are the elements with atomic numbers higher than uranium(#92)

Plutonium-most toxic element known

All synthetic elements are radioactive.

Why? These elements have higher atomic number and are held together less securely than other elements which have fewer p+ and n

0

in their nucleus. Therefore particle or energy can escape from their nuclei,

ie

. Alpha particles, beta particles, and gamma rays.Slide33

SYNTHETIC ELEMENTS cont’dPlutonium-most toxic element knownAll synthetic elements are radioactive.

Why? These elements have higher atomic number and are held together less securely than other elements which have fewer p+ and n

0

in their nucleus. Therefore particle or energy can escape from their nuclei,

ie

. Alpha particles, beta particles, and gamma rays.Slide34

Electron Configurations of GroupsSlide35

Periodic TrendsSlide36

Periodic Law----Periodic TrendsPERIODIC LAW: WHEN ELEMENTS ARE ARRANGED IN ORDER OF INCREASING ATOMIC NUMBER, THERE IS PERIODIC REPETITION OF PHYSICAL AND CHEMICAL PROPERTIES

The properties of the elements within a period change as you move across a period from left to right.

The pattern of properties within a period repeats as you move from one period to the nextSlide37

What are alternative names for these?Slide38

Atomic Radius (Atomic Size)Atomic radius is ½ distance between the nuclei of two atoms of the same element when joined together.

Measured in

picometers

( 1x 10

12

, one trillion)

Atomic size increases from top to bottom in a group

Atomic size decreases from left to right across a periodSlide39

INCREASES from

RIGHT

LEFT

TOP

BOTTOM

HOW DOES ATOMIC RADIUS INCREASE?Slide40

HOW DOES ATOMIC RADIUS INCREASE?Slide41

Cation vs. Ion SizeCations

(lose electrons become smaller)

Anions

(Gain electrons become larger)Slide42

RANK FROM SMALLEST RADIUS TO BIGGESTFluorineHeliumCesium

Francium

Vanadium

Zinc

Silicon

Yttrium

Phosphorus

Jumpstart

4 minutesSlide43

IONIZATION ENERGYSlide44

IONIZATION ENERGYIonization energy is the amount of energy used to remove an electron

Electrons move to higher energy levels when the atom absorbs energy

Electrons need energy to escape the attractive force of the protons Slide45

IONIZATION ENERGYSlide46

IONIZATION ENERGYINCREASES FROM LEFT TO RIGHT ACROSS A PERIOD

Takes more energy to remove e’ from a nonmetal than a metal

DECREASES FROM THE TOP OF A GROUP TO THE BOTTOM

Ex. K has a lower ionization energy than Na.

it is easier to remove an e’ from K than Na.

K is more reactive than NaSlide47

IONIZATION ENERGYSlide48

Element

Atomic #

Ionization Energy

H

1

13.6

Li

3

5.4

K

19

4.3

Na

11

5.1

P

15

11.0

Cl

17

13.0

HOW DOES IONIZATION EN. INCREASE?

L

R, RL, Top Bottom, Bottom Top?Slide49

ELECTRONEGATIVITYSlide50

ElectronegativityWhen atoms bond with each other to form molecules, they share their electrons.

Electronegativity

is the ability an atom has to attract other electrons. Atoms that have high

electronegativities

will attract more electrons and may even steal from other atoms.

Atoms

with low

electronegativities will share the most, sometimes to the point of losing their own electrons. Slide51

Electronegativity Slide52

Elements in the same group have similar behaviors

Because they have the same number of valence electrons!!!

BUT MAGNITUDE CHANGES!Slide53

ReactivitySlide54

REACTIVITYAtoms will undergochemical reactions to Become stable.

Remember: The nature of the universe is that of chaos and all matter is trying to achieve some degree of stability.

Can you think of some examples?Slide55

OCTET RULETHE GOAL OF AN ATOM IS TO HAVE 8 VALENCE ELECTRONS OR A FULL OUTER ENERGY LEVELTHE EXCEPTIONS ARE H AND He

The # of e’ in the outer energy level will determine the chemical properties of the element i.e. different elements with the same # of e’ in the outer energy level will have similar chemical propertiesSlide56

Reactivity

Metals –

more reactive as you go

DOWN a group

Easier to lose electrons

because valence electrons are further away from nucleus

Lower ionization energy

Non-metals –

more reactive as you go

UP

Smaller the atom the more it wants an electron to gain

Higher electronegativity means its easier to take one from another atomSlide57

Reactivity

Most Reactive

Most Reactive

Closest to a

Full

Octet

Full

Valence Shell

Least Reactive

INERTSlide58

ReactivitySlide59

Periodic Trends Summarized