2017 Periodic Table.ppt

The Periodic Table

Mendeleev

• The original periodic table was created by Dmitri Mendeleev.

• He organized the table by atomic mass. • He predicted existence of 3 missing

Modern Periodic Table

• The modern periodic table is organized by atomic number.

• Vertical columns  called groups or families

• Horizontal rows  called periods also represent the shells or energy levels

Major Categories of Elements

• 1) metals 2) non-metals 3) metalloids • Metals are found to the left of the

“staircase”

• Non-metals are found to the right of “staircase”

Properties of Metals

• Solid at room temperature (except Hg) • Shiny, Have luster

• Malleable • Ductile

• Generally have high melting points

Properties of Non-metals

• Can be solid, liquid or gas at room temp • S  examples C, S, I₂

• L  Br₂

• G  O₂, Ne, F₂

• Allotropes- different molecular forms of the same element (different properties, too) O₂ and O₃

• Dull, lack luster • Brittle

Properties of Metalloids

• Solid at room temperature • Semi-conductors

• Metals tend to lose electrons to form a full valence shell and + ions.

Groups on the Periodic Table

• In general, elements found within the same group have similar chemical and physical properties.

Alkali Metals (Group I)

• Metals

• Have one valence electron

• Tend to lose that one electron to become a more stable ion.

Lithium(Li), Sodium(Na), and

Potassium(K)

• Three examples of alkali metals • VERY reactive metals

• Exist as solids at room temperature, but are soft

Applications of Lithium

• Compounds containing Li have many applications:

• lithium hydroxide is used to absorb carbon dioxide in space vehicles

• lithium is used in the manufacture of special high strength glasses and ceramics

Applications of Sodium

• Sodium compounds include:

• "common salt" (sodium chloride, NaCl), • "soda ash" (sodium carbonate, Na₂CO₃)

• "baking soda" (sodium bicarbonate, NaHCO₃) • "caustic soda" (sodium hydroxide, NaOH), are

important to the paper, glass, soap, textile, petroleum, chemical, and metal industries

Applications of Potassium

• The metal is the seventh most abundant and makes up about 1.5 % by weight of the

earth's crust.

Comparing 3 Alkali Metals

Potassium Sodium

Alkaline Earth Metals (Group II)

• Metals

• Have two valence electrons

Magnesium(Mg), Calcium(Ca)

and Strontium(Sr)

• Examples of alkaline earth metals • Exist as solids at room temperature

Applications of Magnesium

• Magnesium is the eighth most abundant element in the earth's crust although not found in it's elemental form.

• used in flares and pyrotechnics

Applications of Calcium

• Forms more than 3% of the earth’s crust

• Is an essential constituent of leaves, bones, teeth, and shells

Applications of Strontium

• fireworks (red flame), flares

• 90Sr is a radioactive isotope produced by

nuclear fallout. 90Sr has the potential for use

as lightweight nuclear producing electricity • used to produce glass for color television

Halogens Group 17

• Have 7 valence electrons • Non-metals (F, Cl, Br, I)

• F, Cl (gases), Br (liquid), I (solid)

• Tend to gain one electron to form a more stable ion

Fluorine

Chlorine

Noble Gases Group 18

• Very stable because of filled valence shell. • Do not react in the presence of other

elements (relatively inert)

Argon

• Used in light bulbs and lasers.

Xenon

Transition Metals

• Also known as “heavy metals” • Tend to be very dense

• Have varying reactivity

• Have multiple oxidation states (can form more than one ion)

Copper

Nickel

Silver

Lanthanide and Actinide Series

• Rare earth metals

Periodic Trends

• Trends occur in the periodic table in the following areas:

-reactivity -metallic/non-metallic character -atomic radius* -ionization energy* -ionic radius -electronegativity*

Reactivity (metals)

• Atoms react when they gain, lose or share electrons (bonding).

Metals – lose e-,

bigger loser = more reactive

Reactivity (non metals)

• Atoms react when they gain, lose or share electrons (bonding).

non metals – gain e-,

Better gainer = more reactive

Metallic Character

• Remember best metal is Francium (lower left) • Metallic character is relative to Fr.

• Across a period (away from Fr) metallic character decreases.

Non metallic Character

• Remember best non metal is Fluorine (upper right)

• Non metallic character is relative to F.

• Across a period (towards F) non metallic character increases.

Atomic Radius

Atomic radius provides a basis for the size of an atom.

Atomic radius is equal to half the distance

between 2 neighboring nuclei of the same

Group Trends in Atomic Radius

• As you move down a group in the periodic table, atomic radius generally increases.

• This is due to the fact that as you move down a column the number of shells increases

Period Trends in Atomic Radius

• As one moves across a period of the

Periodic Table, atomic radius generally decreases.

• This is due to the fact that each successive element has one more proton that increases the nuclear charge. This positive charge

Period Trends in Atomic Radius

Ionization Energy

• The energy required to remove an electron from an atom is known as the FIRST

IONIZATION ENERGY.

• To remove a second electron requires what is called the SECOND IONIZATION

Group Trends in Ionization Energy

• As one moves down a group, first

ionization energy generally decreases. • This is due to the fact that as one moves

An Analogy: Football

• Remember, as atomic size increases, the outermost electrons become further away from the nucleus.

• If a football player is holding the ball very close to himself, it is more difficult to

remove it from him.

• If a football player is holding the ball far

Period Trends in Ionization Energy

• As one moves across a period of the Periodic Table, first ionization energy generally

increases.

• This is due the fact that as atomic number (number of protons) increases, so does

nuclear charge.

Another Analogy: Football

• Increasing atomic number and

therefore nuclear charge would be analogous to the football player building strength.

Stop and Practice

How would you describe the

atomic radius of a period-2

alkaline earth metal with that

of a period-4 alkaline earth

metal?

Answer: The atomic radius of a period-2

More practice

Which has a larger atomic

radius within the same

period: a halogen or an

alkali metal?

Answer: An alkali metal has a larger

More Practice

Which element in group 16 has the highest first ionization

energy? In period 2?

Ion Formation

• Atoms with low ionization energies (they lose electrons easily) form positive ions (CATIONS). Metals do this.

• Atoms with high ionization energies tend to gain electrons to form negative ions

Ionic Size (Cations)

• The gaining or loss of an electron affects the size of atom (that

turns into an ion). • Positive ions are

Cation Size

• When an electron is lost from an atom, the

nucleus now has more pull on the outer energy level making the ion SMALLER.

MINUS ONE

Ionic Size (Anions)

Anion Size

• When an electron is gained the nucleus now has less pull on the outer energy level making the ion

LARGER.

Trends in Ionic Radius

(Both Cations and Anions)

Electronegativity

• Can be defined as an atom’s ability to attract electrons. • Expressed in arbitrary units

on Table S of your Reference Tables.

• Non-metals tend to have higher electronegativities because they like to gain electrons.

atoms

Trends in Electronegativity

• In one sentence

THE CLOSER AN ATOM IS TO

FLUORINE ON THE PERIODIC TABLE, THE HIGHER THE

ELECTRONEGATIVITY.

Stop and Practice

How does the ionic radius of

sodium compare with that of

cesium? Boron with fluorine?