Periodic Table Groups
Group 1: Alkali Metals All metals, except for hydrogen React violently and quickly Form ions with a charge of +1 One valence electron
Group 2: Alkaline-Earth Metals Very reactive Harder and denser than group 1 Form ions with a charge of +2 Two valence electrons
Group 3-12: Transition Metals Malleable (flat sheets) Ductile (made into a wire) Lusterous (shiny) Cannot tell their valence electrons from looking at their group #
F-Block: Rare Earth Metals Plentiful in Earth’s crust, but not found in large quantities at a time Many are man-made Many are radioactive
Group 17: Halogens Contains elements in each state of matter Extremely reactive Form diatomic molecules Form ions with a -1 charge Seven valence electrons
Group 18: Noble Gases Extremely unreactive Do not form ions, stable All gases Eight valence electrons, except He
Periodic Trends Atomic radius Electronegativity Ions & Ionic Radius Ionization energy Reactivity & Metallic properties
Atomic Radius Distance from the nucleus to the outer valence electron
Radius increases down a group since we add energy levels.
Effective Nuclear Charge- Strong force pulling the electrons toward the nucleus (like a magnet) This is because of the positive pull from the protons in the nucleus on the negative electrons As you go LR, you add 1 p+ and 1 e- increasing the attractive force
radius decreases from L R b/c the more e- the more pull from the p+ in the nucleus making the atom SMALLER
Valence (outer) electrons 1 8 2 3 4 5 6 7 Re-emphasize why an element will more likely lose or gain an electrons, Octet Rule
Backwards again!!! UGH! Atoms that become Cations lose electrons to become positive and smaller Atoms that become Anions gain electrons to become negative and larger
Common charges – oxidation #’s 1+ 2+ 3+ 4± 3- 2- 1- Metals LOSE Nonmetals GAIN Re-emphasize why an element will more likely lose or gain an electrons, Octet Rule
Ionic Radius – size of the atom after it gains or loses an electron Cation- smaller than its neutral atom (because it loses electrons) Anion- larger than its neutral atom (because it gains electrons)
Neutral atom is in gray Cation (+) is in red - notice it is SMALLER than the neutral Anion (-) is in blue - notice it is BIGGER than the neutral
5 4 Let’s Practice! Name Symbo l At # e- in neutral atom e- in ion ox # cation anion neither or both Group Period Valence e- 5 4
(new flap) Electronegativity The tendency for an atom to attract electrons to itself when it is chemically combined with another element.
Tug of war for shared electrons Electronegativity L VE of electrons Tug of war for shared electrons Pair of Shared Electrons
Noble gases (group 18) are already stable with 8 electrons in their outer shell (NO LOVE!!) Floozy Fluorine is the most electronegative element. Electronegativity increases from L R Electronegativity decreases going down
Electronegativity http://www.webelements.com/webelements/properties/text/image-balls/electroneg-pauling.html
First Ionization Energies (Group) As you go down a group IE decreases since you’re adding energy levels (easier to steal)
First Ionization Energies (Period) Since the effective nuclear charge increases as you go across the period (left to right), electrons are held tighter by the nucleus and require more energy to be removed (high IE = harder to steal).
First Ionization Energies http://www.iun.edu/~cpanhd/C101webnotes/modern-atomic-theory/ionization-energy.html
2nd Ionization Energy Energy required to remove a second electron from the outermost electrons.
Ionization Energies
Metallic Properties Having properties of a metal ie, luster, malleability, ductility Increase down a group. Increase across a period Right to left Francium Fr- most metallic
Metallic Properties
Reactivity The state and degree to which a substance will react with another substance. N O E
Energy released when an atom gains an electron
Electron The electron is the most important subatomic particle in determining physical and chemical properties.