PERIODIC TABLE

The Language of Chemistry• CHEMICAL ELEMENTS -

– pure substances that cannot be decomposed by ordinary means to other substances.

Sodium Bromine

Aluminum

The Language of Chemistry

• The elements, their names, and symbols are given on the PERIODIC TABLE

The Periodic Table

Dmitri Mendeleev (1834 - 1907) arranged elements in order of increasing atomic mass.

Groups in the Periodic Table

Vertical columns

Elements in groups react in similar ways!Have similar chemical and physical properties

Periods in the Periodic Table

Horizontal rows = 7

Regions of the Periodic Table

3 classes of elementsMetals

Nonmetalsmetalloids

METALS• 80% of elements are metals• Metallic lust, shiny• Good conductors (heat, electricity)• Solid at room temperature (except Hg)• Ductile – can be pulled through wires• Malleable

NonMetals• Most are gases at room temperature• Dull color if solid• P and S are solids• Br - liquid• Poor conductors of heat and temperature

– Carbon is the exception

METALLOIDS• Have characteristics of metals and nonmetals• Can be metallic• Brittle (not malleable or ductile• Semiconductors ( Si)

Group 1A: Alkali Metals

Cutting sodium metal

Silvery coloredVery Reactivehttp://www.youtube.com/watch?v=QSZ-3wScePMMalleable,ductile good conductorssoft

Magnesium

Magnesium oxide

Group 2A: Alkaline Earth Metals

Very reactive

Transition Elements

Lanthanides and actinidesCan have several oxidation (Lose Electrons) states

Malleable

Good conductors of electricity and heat

Iron, Cobalt and Nickel can create magneticfields

Group 7A: The Halogens (salt makers) F, Cl, Br, I, At

Non MetalsExtremely

reactive/Dangerous Forms salts (NaCl)Forms Acids (HF)

Used in: lamps (halogen), Teflon (Flourine + Carbon)

http://www.youtube.com/watch?v=u2ogMUDBaf4&feature=related

Group 8A: The Noble (Inert) Gases

He, Ne, Ar, Kr, Xe, Rn• Lighter than air

balloons• “Neon” signs• Very Unreactive

because they have full electron shells

XeOF4

The Periodic Table -Review

1. Name group 1

2. Name group 7

3. 2 Characteristics of metals

4. 2 characteristics of nonmetals

PERIODIC TRENDS

• Atomic size- Increase in atomic number draws electrons closer to the nucleus = smaller

Ionization Energy• The energy required to remove an electron

from an atom in order to form an ion• Easy to remove electrons from group 1A more

difficult to remove electrons across a row

IONS • IONS are atoms or groups of atoms with a

positive or negative charge. • Taking away an electron from an atom gives a

CATION with a positive charge• Adding an electron to an atom gives an

ANION with a negative charge.• To tell the difference between an atom and an

ion, look to see if there is a charge in the superscript! Examples: Na+ Ca+2 I- O-2

Na Ca I O

Forming Cations & Anions

A CATION forms when an atom loses one or more electrons.

An ANION forms when an atom gains one or more electrons

Mg --> Mg2+ + 2 e- F + e- --> F-

PREDICTING ION CHARGES

In general

• metals (Mg) lose electrons ---> cations• nonmetals (F) gain electrons ---> anions

Charges on Common Ions

-1-2-3+1+2

By losing or gaining e-, atom has same number of e-’s as nearest Group 8A atom.

Ionic Size

• Cations are always smaller than the atoms they form

• Anions are always larger than the atoms from which they form

Electronegativity

• Ability of an atom in an element to attract electrons when the atom is in a compound