Unit 4: Overview- Honors Chemistry

Periodic Table

Classifying Octet Rule

Metals: Increasing stability /lowering Reactivity, valence , Alkali, alkaline earth, energy (Coulomb's law) core charge, atomic radii, transition, inner transition valence electrons, cations, ionic radii, ,

(rare earth- lanthanides and anions actinides)

Non-metals:

Halogens, noble gases

Metalloids

Enduring Understandings

I. Chemists use the properties of elements to sort them into groups.  Mendeleev arranged the elements in his periodic table in order of increasing atomic mass. Science has predictive power. Mendeleev was able to use his table to predict the properties of undiscovered elements.  Moseley studied atoms with x-rays and arranged his periodic table in order of increasing atomic number. For the first time, regions of the periodic table were “filled.”

II. Valence electrons- electrons in the highest occupied energy level (n)  For any representative element- use group number to determine the number of valence electrons.  Valence electrons and valence shell configuration influence physical and chemical properties considerably

III. Shielding- valence electrons experience less nuclear attraction due to two contributing factors:  Distance from the nucleus (valence electrons are further from the nucleus)  Electron repulsion (valence electrons are repelled outward by electrons in the core of the )

IV. Octet rule- in forming compounds, atoms tend to seek the lower energy / greater stability by achieving the of the nearest noble gas.  Metals lose electrons while forming octets  Non-metals gain electrons while forming octets

V. Ions- atoms or group of atoms with a charge  Cations are positively charged ions that are often formed from group IA-IIIA metals.  Anions are negatively charged ions that are often formed from group VA-VIIA non-metals.

VI. Ionization energy- energy required to remove an outermost electron

VII. Electronegativity- ability of an element to attract electrons toward itself when bonding in a compound  Pauling scale- relative indication of electronegativity; based on fluorine (F) as highest- 4.0

VIII. Physical and chemical properties are a function of atomic number.  Reactivity  Atomic / ionic radius Decreasing across series- valence electrons and core charge increasing Increasing down group- shielding  Ionization energy Increasing across series- moving toward non-metals with smaller radius that are seeking octet by gaining electrons Decreasing down group- shielding (easier to remove a when more shells are present)  Electronegativity Increasing across series- moving toward non-metals with smaller radius that are seeking octet by gaining electrons Decreasing down group- shielding (harder to attract electrons with more shells present)