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 MetalloidsThe 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+1
Cu+2
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
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!