The Periodic Table

The Periodic TableElements

Why is the Periodic Table important to me?

• The periodic table is the most useful tool to a chemist.

• You get to use it on every test.

• It organizes lots of information about all the known elements.

Pre-Periodic Table Chemistry …

• …was a mess!!!• No organization of

elements.• Imagine going to a grocery

store with no organization!!• Difficult to find information.• Chemistry didn’t make

sense.

Discovery of Elements

• Science has come along way since Aristotle’s theory of Air, Water, Fire, and Earth.

• Scientists have identified 90 naturally occurring elements, and created about 28 others.

The most abundant element in the earth’s crust is oxygen.

Dmitri Mendeleev: Father of the Table

HOW HIS WORKED…• Put elements in rows by

increasing atomic weight.• Put elements in columns

by the way they reacted.

SOME PROBLEMS…• He left blank spaces for

what he said were undiscovered elements. (Turned out he was right!)

• He broke the pattern of increasing atomic weight to keep similar reacting elements together.

The Current Periodic Table• Mendeleev wasn’t too far off.

•Now the elements are put in rows by increasing

ATOMIC NUMBER!!• The horizontal rows are called periods and are

labeled from 1 to 7.• The vertical columns are called (families) groups are

labeled from 1 to 18.

Families • Columns of elements are called groups or families. • Elements in each family have similar but not identical

properties.• For example, lithium (Li), sodium (Na), potassium (K),

and other members of family IA are all soft, white, shiny metals.

• All elements in a family have the same number of valence electrons.

Periods

• Each horizontal row of elements is called a period.• The elements in a period are not alike in properties.• In fact, the properties change greatly across even given

row.• The first element in a period is always an extremely

active solid. The last element in a period, is always an inactive gas.

Groups…Here’s Where the Periodic Table Gets Useful!!• Elements in the

same group have similar chemical and physical properties!!

• (Mendeleev did that on purpose.)

Why??• They have the same

number of valence electrons.

• They will form the same kinds of ions.

Families on the Periodic Table

• Columns are groups of families.

• Families may be one column, or several columns put together.

• Families have names rather than numbers. (Just like your family has a common last name.)

Vocabulary used to explain metals.Malleable = can be pounded into thin sheets

Ductile = can be drawn out into a thin wire

Lustrous: Shiny Brittle: hard but easy to break.

Hydrogen • Hydrogen belongs to a family of its own.

• Hydrogen is a diatomic, reactive gas.• Hydrogen was involved in the

explosion of the Hindenberg.• Hydrogen is promising as an

alternative fuel source for automobiles• Hydrogen bomb

Alkali Metals

• 1st column on the periodic table (Group 1) not including hydrogen.

• Most reactive metals, always combined with something else in nature (like in salt).

• Soft enough to cut with a butter knife

• They react violently with water.

What does it mean to be reactive?– An incomplete valence electron level.– All atoms (except hydrogen) want to

have 8 electrons in their very outermost energy level (This is

called the rule of octet.)– Atoms bond until this level is

complete. Atoms with few valence electrons lose them during bonding. Atoms with 6, 7, or 8 valence electrons gain electrons during bonding.

Alkaline Earth Metals

• Second column on the periodic table. (Group 2)

• Reactive metals that are always combined with nonmetals in nature.

• Several of these elements are important mineral nutrients (such as Mg and Ca

Transition Metals

• Elements in groups 3-12• Less reactive harder metals• Includes metals used in jewelry and

construction.• Metals used “as metal.”

Metalloids “The Ladder”Properties between metals and nonmetals

Sometimes lose and sometimes gain electrons

Ex: Si appears lustrous, is brittle, not malleable or ductile. Poorer conductor of heat and electricity than metals.

Useful in the semiconductor industry.

Gases• Boron Family• Carbon Family• Nitrogen Family• Oxygen Family• Halogens• Noble Gases

Boron Family

• Elements in group 13• Aluminum metal was once

rare and expensive, not a “disposable metal.”

Carbon Family• Elements in group 14• Contains elements important to life

and computers.• Carbon is the basis for an entire

branch of chemistry.• Silicon and Germanium are

important semiconductors.

Nitrogen Family• Elements in group 15• Nitrogen makes up over ¾

of the atmosphere.• Nitrogen and phosphorus

are both important in living things.

• Most of the world’s nitrogen is not available to living things.

• The red stuff on the tip of matches is phosphorus.

Oxygen Family or Chalcogens• Elements in group 16• Oxygen is necessary for

respiration and combustion.• Many things that stink, contain

sulfur (rotten eggs, garlic, skunks,etc.)

Halogens

• Elements in group 17• Very reactive, volatile,

diatomic, nonmetals• Always found combined

with other element in nature .

• Used as disinfectants and to strengthen teeth.

The Noble Gases

The Noble Gases

• Elements in group 18• VERY unreactive,

monatomic gases• Used in lighted “neon”

signs• Used in blimps to fix the

Hindenberg problem.• Have a full valence

shell.

Lanthanide and Actinide series.• The 30 rare earth

elements are composed of the lanthanide and actinide series.

• One element of the lanthanide series and most of the elements in the actinide series are called trans-uranium, which means synthetic or man-made.

Periodic Trends

• Atomic Radii• Electronegativity• Ionization Energy• Electron Affinity

Atomic Radii(Radius)Increase

down group

Decrease across period

ElectronegativityType of Measure

Ability of an atom to attract electrons– Dec. down

group (electron shielding)

– Inc. across period

Ionization Energy

Amount of energy needed to remove an electron– Inc. across

period– Dec. down group

(electron shielding)

Electron Affinity

Amount of energy released when an electron is added to a neutral atom.

Periodic Trends1. Rank the following elements by increasing atomic radius:

C, Al, O, K.2. Rank the following elements by increasing electronegativity:

S, O, Ne, Al.3. What is the difference between electron affinity and ionization

energy?

4. Why does fluorine have a higher ionization energy than iodine?

5. Why do elements in the same family generally have similar

properties?

O, C, Al, K

Al, S,O,Ne

EA. Ability to attract electrons and I.E.energy to remove electron

Fluorine is located above the Iodine in the column.

They have identical number of electrons in their outermost shell.

Matter

• All matter is composed of atoms and groups of atoms bonded together, called molecules.– Substances that are made from one type of atom only are

called pure substances. Can not be separated chemically or physically.

– Substances that are made from more than one or more than one type of atom bonded together are called compounds. Can be separated by chemical means only.

– Compounds that are combined physically, but not chemically, are called mixtures. Can be separated.

Elements, Compounds, Mixtures

• Sodium(Na+) an element.• Chlorine (Cl-) is an element.• When sodium and chlorine bond they make the

compound sodium chloride(NaCl), commonly known as table salt.

Salt is a compound.

Ocean is a mixture

Elements, compounds, and mixtures

• Mixtures can be separated by physical means.• Compounds can only be separated by chemical

means.• Elements are pure substances. When the

subatomic particles of an element are separated from its atom, it no longer retains the properties of that element.