The Periodic Table of Elements

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Classifying Elements: The Periodic Table

Periodic Law: Properties of periodic elements are functions of their atomic numbers.

Dmitri Mendeleev: arranged all of the known elements into the periodic table.

What is the Periodic Table?

~This table is organized by atomic number and gives physical/chemical/and atomic characteristics of each element by grouping similar ones together.

Periodic Table: Chemical Symbols

Each element is represented by a single capital letter pair of letters, or three letters with the first letter of the set being capitalized. (Ex: single letter = N, pair= Na)

Each letter corresponds to the name of the element, however some are derived from other languages (Ex: Sodium is labeled “Na” due to its Latin name “natrium”.

Use IUPAC naming system.

Reading the Periodic Table

Definitions Atomic Number: The number of protons in the

nucleus of an atom.

Oxidation States: State of an element in which number of electrons differs.

Symbol: The letter(s) used to express a specific element

Atomic Mass: Number of protons and neutrons added together (Ex: Oxygen~ 8 protons +8 neutrons= mass of 16)

Electron Configuration: The arrangement of electrons around the nucleus of an atom in its ground state.

Trends: Definitions Atomic Radii: half the distance between two adjacent

atoms in a crystal.

Ionization Energy: the amount of energy needed to remove the most loosely bound electron from a neutral atom.

Ionic Radii: distance from the nucleus to the outer energy level of the ion.

Electronegativity: value of an atom is a measure of its attraction for electrons when bonded to another atom.

Periodic Table: Periods Placed in horizontal rows with the number beginning

the period showing its principle energy level. (Ex: Potassium (K) is in period 4, so it has electrons in the fourth principle energy level).

The number of valence electrons increases from left to right.

There are 7 periods!

Groups & Families Organized by vertical columns.

Each member of a specific group contains the same number of valence electrons.

Members of the same group/family have similar chemical properties and characteristics (just like you have similar characteristics to those in your family!)

Group 1 & 2

Group 1: Alkali Metals

Group 2: Alkaline Earth Metals

Both groups show typical metallic characteristics, easily lose their electrons, and are always found in compounds in nature (never in their atomic state).

Both have low ionization energy and electronegativity.

Group 1 Alkali Metals are the most reactive metals on the

periodic table and do not exist free in nature. They must be stored under oil or they will quickly oxidize . They have very low ionization energy and give up their outer electrons very easily. They are very soft metals that can be cut with a knife. They react violently with water. The lower the ionization energy the more reactive these metals. So, lithium is the least reactive and Cesium is the most reactive.

Group 2

Group 3-12 Transition elements tend to have high tensile strength, density and

melting and boiling points. As with many properties of transition metals, this is due to d orbital electrons' ability to delocalize within the metal lattice. In metallic substances, the more electrons shared between nuclei, the stronger the metal.

There are several common characteristic properties of transition elements:

They often form colored compounds.

They can have a variety of different oxidation states.

At least one of their compounds has an incomplete d-electron subshell.

They are often good catalysts.

They are silvery-blue at room temperature (except copper and gold).

They are solids at room temperature (except mercury).

They form complex ions (aqua ions included).

They are often paramagnetic.

These are the metals you think of….

Special Transition Metals

Lanthanoids and Actinoids are Transition Metals, but are separated because their reactivity is very different than those of the main transition period.

These elements are much more RADIOACTIVE.

Group 15 & 16 Are the border line of elements with metallic and non-

metallic characteristics from top to bottom of the group.

Group 17

Also known as the “Halogens”.

Only occur in nature in combined state.

Fluorine is the most reactive Halogen.

Group 18

Also known as the “Noble Gases”

Elements of this group have a complete “octet” (8 electrons) or outer energy level, so they are chemically un-reactive.

Groups: Hydrogen is the Exception

Hydrogen does not belong to Group 1 and does not have similar characteristics to its neighboring metals.

Sections on the Periodic Table Elements in the Periodic Table are grouped due to

similar characteristics: Metals, Non-Metals, Metalloids, and Noble Gases.

Metals Most known elements are metals

Most active metals are located in Groups 1 & 2

Metallic properties increase from top to bottom of the group

Standard Properties of Metals:

Solids at room Temperature (72⁰F) except Mercury which is liquid (used in old thermometers),

Most have density greater than water (sink) except alkali metals

Are malleable (shaped)

Ductile (can be made into wire)

Have luster (shiney)

can conduct heat and electricity

have low ionization energy/electronegativity values

tend to lose electrons (become positive)

Metals: Transition Metals/Elements

Groups 3-12 which have the outermost d orbitals filled

Typically hard solids

Have multiple oxidation states

Less reactive than groups 1 and 2

Often form ions that have color

Metalloids Sometimes called “Semimetals”

Can be found adjacent to the diagonal of the stair-step line.

Are an intermediate element that embody both metal and non-metal characteristics

Metalloids Seven elements on the Periodic table have

somewhat metal/non-metal characteristics.

All are located near the “Step” line in between metals and non-metal elements.

The special 7 include: B, Si, Ge, As, Sb, Te, Po, and At

Non-Metals Standard Properties of non-metals:

Many are gases or molecular solids at room temperature (except Bromine is a liquid)

Not malleable or ductile

Tend to be brittle and lack luster

High ionization energy and electronegativity values

Poor conductors of heat and electricity

Tend to gain electrons and become negative

Gases: Noble Gases

Located in Group 18

Are very unreactive, so they do not have many non-metal properties

Has a completely filled outer shell

Have a complete “Octet” and are very stable

Allotropes When non-metals can exist in two or more forms in

the same phase. Example: O3 and O2 both are in the gaseous state.

Allotropes will have different chemical properties

EXAMPLE: Carbon can be found as graphite and diamond…both have very different properties, but are Carbon with the formula of C60

Test Your Skills!

Trends: Atomic Radii/Size

Atomic Size increase toward the left and downward!

Size dealing with Cations/Anions Cations (positive character) usually are smaller than

Anions (negative) due to the loss of electrons around their nucleus. Less electrons means less rings which take up less space due to greater pull inward from the electrons.

Trends: Ionization Energy

Ionization energy increases going toward the right and up!

Trends: Ionic Size

Ionic Size increases to the left and downward!

Trends: Electronegativity

Electronegativity increases toward the right and upward!