The Periodic LawThe Periodic Law

Dmitri Mendeleev (1860) When the elements are placed in order by increasing atomic mass, their properties repeat in a periodic way.

Moseley (~1910)

Changed the elements’ order from atomic mass to atomic number.

An atom’s chemical properties are determined by its valence (outside energy level) electrons. The identity of the element (what element an atom is) is determined by the number of protons it has.

Protons

Atoms tend to lose, gain or share electrons in order to get an electron configuration like a noble gas.

                        

Elements are arranged:

Vertically into Groups

Horizontally Into Periods

Arrangement of Table

Metals

Metalloids

Nonmetals

Metals

• Over 75% of the elements are classified as metals.

• They are located to the left and lower parts of the periodic table.

a. Malleable a. Capable of being shaped or formed by being

hammered

b. Usually shiny, gray coloredc. Conduct electricity d. Conduct heate. Ductile

a. Capable of being drawn out into a wire

f. Usually solids at room temperature

Properties of Metals

Metals Form Cations & Metals Form Cations & AlloysAlloys

Metals Form Cations & Metals Form Cations & AlloysAlloys

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

Metals are mixed with other metals to form alloys.

Mg --> Mg2+ + 2 e- Stainless Steel Refrigerator

Nonmetals

• They are found in the upper right part of the table.

Metals

Metalloids

Nonmetals

Nonmetal properties are more diverse than the metals.

• solid, liquid, or gas at room temp

•usually poor heat conductors

•usually poor electrical conductors

•solids are brittle

An ANION forms when an atom gains one or more electrons

Nonmetals Form AnionsNonmetals Form AnionsNonmetals Form AnionsNonmetals Form Anions

Metalloids (also called semimetals)

• They are found on the table between the metals and the nonmetals.

Metals

Metalloids

Nonmetals

•They have properties of both metals and nonmetals.

Examples are silicon, arsenic, and germanium

Periods (Energy Levels)

• There are 7 periods in the periodic table.

• The inner transition metals are actually “inside” periods 6 and 7.

Horizontally Rows

Periodic Trends

• Across a period, atomic radius tends to decrease .

• Across a period, ionization energy tends to increase .

Elements are arranged:

Vertically into

Groups (also called chemical families)

Groups

• Eight tall groups of main group (representative) elements, numbers ending in A, or #1-2 & 13-18.

• Ten shorter groups of transition metals, numbers ending in B or #3-12.

• Elements in the same group have the same valence electron configuration, and therefore have similar chemical and physical properties.

Down a group, atomic radius increases and

ionization energy decreases.

Increasing

Increasing

Alkali Metals

reacting with water:

• Li (Lithium) – least reactive

• Na (Sodium)

• K (Potassium)

• Rb (Rubidium)• Cs (Cesium) – more reactive

What would you expect from Francium?!?!

Group or Family Members

Group 1A: Alkali Metals Group 1A: Alkali Metals PropertiesProperties

Group 1A: Alkali Metals Group 1A: Alkali Metals PropertiesProperties

Group 1A: Alkali Metals Group 1A: Alkali Metals PropertiesProperties

Group 1A: Alkali Metals Group 1A: Alkali Metals PropertiesProperties

2) Highly reactive with H2O to form alkaline solution.

Valence electron configuration (period)s1

1) Soft, silver-colored metals

Group 1A: Alkali Metals Group 1A: Alkali Metals Properties cont.Properties cont.

Group 1A: Alkali Metals Group 1A: Alkali Metals Properties cont.Properties cont.

3) They tend to form +1 ions

4) Low density (some float in water

Li --> Li1+ + 1 e-

They are part of the s block.

Now get one color and outline the Alkali Metal Family.

Group 2A: Alkaline Earth Metals

Silvery-White Metals

Many are found in rocks in the earth’s crust

Group 2A: Alkaline Earth Metals cont.

Valence electron configuration (period) s2

Group 2A: Alkaline Earth Metals Properties

1)react w/water to form alkaline solution

2)not as reactive as Group 1

3)not as soft as Group 1

4)tend to form +2 ions Mg --> Mg2+ + 2 e-

Part of the s-block

Now get one color and outline the Alkaline Earth Metal Family.

Groups 3B through 2B or 3 through 12 Transition Metals

Groups 3B through 2B or 3 through 12 Transition Metals

Properties

1) often form colored compounds

2) harder than Groups 1 and 2

Groups 3B through 2B or 3 through 12 Transition Metals

Many of these elements can form ions with varying charges, such as Fe+3/Fe+2, Cu+2/Cu+1

Part of the d-block

Now get one color and outline the Transition Metals

Groups 3A or 13: Boron Family (sometimes known as Aluminum

Family)

Valence electron configuration (period) s2 p1

Properties become more metallic down the group.

Part of the p -block

Now get one color and outline the Boron Family (sometimes known as Aluminum Family)

Groups 4A or 14: Carbon Family

nonmetals C

metalloids Si, Ge

metals Sn, Pb

Groups 4A or 14: Carbon Family cont.

Valence electron configuration (period) s2 p2

Properties become more metallic down the group.

Part of the p -block

Groups 4A or 14: Carbon Family cont.

Elements that exist in more than one form are called allotropes.

An example is carbon in forms of

Graphite Diamonds Buckyballs Amorphic

Now get one color and outline the Carbon Family

Group 5A or 15: Nitrogen Family

nonmetals N, P

metalloids As, Sb

metals Bi

Group 5A or 15: Nitrogen Family

Valence electron configuration (period) s2 p3

Properties become more metallic down the group.

Nonmetals tend to form ions with - 3 charge.

Part of the p -block

N --> N3- + 3 e-

Now get one color and outline the Nitrogen Family

Group 6A or 16: Oxygen Family

nonmetals O, S, Se

metalloid Te

metals Po

Valence electron configuration (period) s2 p4

Group 6A or 16: Oxygen Family

Properties become more metallic down the group.

Nonmetals tend to form ions with - 2 charge. O --> O2- + 2 e-

Part of the p -block

Important allotropes from this group are oxygen in forms O2, oxygen gas and O3, ozone

Now get one color and outline the Oxygen Family

Group 7A or 17: Halogen Family (“saltmakers”)

Members – all nonmetals F, Cl, Br, I, At

Valence electron configuration (period) s2 p5

Part of the p -block

Group 7A or 17: Halogen Family (“saltmakers”) cont.

Very reactive, electronegative (measurement of the attraction for electrons) because these atoms need only one electron to have the same electron configuration as a noble gas.

Tend to form ions with - 1 charge.

F --> F1- + 1 e-

Now get one color and outline the Halogen Family

Group 8A or 18: Noble Gases

Sometimes called “inert gases,” though most can be made to react.

Valence electron configuration for He 1s2, all others (period) s2 p6

Group 8A or 18: Noble Gases cont.

Properties

1. all are gases at room temp

2. relatively unreactive

Part of the p -block

They have no common ionic charge because they don’t form ions, have stable electron configurations

Now get one color and outline the Noble Gases

Inner Transition Metals

Usually considered together because of their similar properties.

Belong inside periods 6 and 7, but are moved to fit on a page better.

Elements 57-71 are called the lanthanides; 89—103 are the actinides.

Inner Transition Metals cont.

Part of the f block

Many of these are radioactive (have unstable nuclei); Pm and all elements past uranium are radioactive.

Tend to form ions with +3 charge.

Now get one color and outline the Inner Transition Metals