The Periodic Table!

Important People to Remember Dmitri Mendeleev - published 1st periodic table in 1869 - arranged elements by atomic mass

Important People to Remember Henry Moseley - arranged the periodic table for today - arranged elements by atomic number

Groups and Periods On the periodic table: Elements are arranged according to similar properties. Periods Groups Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Metals, Nonmetals, and Metalloids The heavy zigzag line separates metals and nonmetals. Metals are located to the left. Nonmetals are located to the right. Metalloids are located along the heavy zigzag line between the metals and nonmetals. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Metals To the left of the Zigzag Malleable (smashed into thin sheets) Ductile (stretched into wires) Conduct heat and electricity Shiny Reactive High Melting Points Mostly Solids at room temperature - except Hg (liquid)

Examples of Metals Fe

Non-Metals Right of the zigzag (Upper right side) Poor conductor of electricity Dull Brittle Low Melting Points Mostly gases at room temperature Liquid (Bromine) Solids (Sulfur, Phosphorus, Carbon)

Examples of Nonmetals Sulfur Carbon

Metalloids Along the zigzag line! Has properties of both metals AND nonmetals! Somewhat shiny solids, not much luster Semiconductive B, Si, Ge, As, Sb, Te, Po, At

Examples of Metalloids Silicon

Names of Some Representative Elements Several groups of representative elements are known by common names. Copyright © 2008 by Pearson Education, Inc. Publishing as Benjamin Cummings

Alkali Metals Group 1: Li, Na, K, Rb, Cs, Fr VERY reactive Soft Metals Rarely exist in nature alone Form salts when combined

Alkaline Earth Metals Group 2: Be, Mg, Ca, Sr, Ba, Ra Reactive Found in compounds that are in the Earth’s Crust More dense and harder than alkali metals

Transition Metals In the middle (d-block) Much LESS reactive Electron in highest energy level can change Therefore when they form ions, their charges can vary.

Examples: Cu+2 Cu+1

Halogens Group 7: F, Cl, Br, I, At Most reactive non metals Fluorine most reactive non metal Physical properties very within group

Noble Gases Group 8: He, Ne, Ar, Kr, Xe, Rn Don’t react or combine with anyone! (Unless forced) INERT GASES Low Boiling Points All gases at room temperture

Lanthanides Elements 58-71 - All occur in nature except 61 Rare earth metals Very reactive High melting points and boiling points Used in lamps, lasers, magnets, and motion picture projectors.

Actinides Elements 90-103 Most are synthetic (man-made) Almost all are radio active Very dense Can be found in smoke detectors, nuclear weapons, and radio active minerals

Periodic Law Periodic Law = trends that occur throughout the periodic table -Atomic Radius -Ionization Energy -Electronegativity

How are the elements organized? Atoms in the same group have the same number of valence electrons. Outer shell = valence shell (outside electrons) 8 valence electrons= stable Valence electrons determine reactivity and how strongly an atom will bond with other atoms.

Determine Valence Electrons These atoms want 8 valence electrons - Is it easier for them to gain or lose a certain amount of electrons?

Atomic Radius Trend What is atomic radius? - Distance from the nucleus to the valence electrons - It’s the size of the atom!

Atomic Radius -As you go across the period what happens to the atomic radius? -As you go down a group what happens to the atomic radius?

Atomic Radius Trend More attractions = SMALL atomic radius As you go across a period, the number of protons increases (e- increase too, but on the same energy level). More p+ can pull in e- closer, decreasing the radius. More attractions = SMALL atomic radius As you go down a group, e- are added to new energy levels. Each level is further from the nucleus, which increases the radius. More energy levels = LARGE atomic radius

Electronegativity Electronegativity is the atom’s want to gain electrons An atoms LOVE for electrons!!

Electronegativity What happens when you go across a period? Down a group?

Electronegativity As you go across a period, electrons are held more closely because the atomic radius decreases. It is easier to attract electrons, so electronegativity increases. Small radius (more attractions) = HIGH electronegativity As you move down a group, electrons are further away from nucleus because the atomic radius increases. It is harder to attract electrons, so electronegativity decreases. Large radius (less attractions) = LOW electronegativity

Electronegativity Look at the dot structures! The atom that wants to GAIN electrons will have a high electronegativity!

Ionization energy Ionization Energy is the energy needed to remove a valence electron -What do see as you go across the period? -What happens to the energy going down a group?

Ionization energy •As you go across a period, electrons are held more closely because the atomic radius decreases. It is easier to attract electrons, so electronegativity increases. Small radius (more attractions) = HIGH ionization energy As you go down a group, electrons are further from nucleus because the atomic radius increases. It takes less energy to remove an electron, so the ionization energy decreases. Large radius (less attractions) = LOW ionization energy You can also look at the dot structures!