Topic 3 Periodicity

Topic 3 Periodicity - Topic 3 Periodicity 3.2 physical...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Topic 3 Periodicity 3.2 physical properties 3.2.1 Define the term first ionization energy and electronegativity First ionization energy: energy required to remove the first electron from an atom Electronegativity: chemical property; tendency of an atom to attract electrons 3.2.2 Describe and explain the trends in atomic radii, ionic radii, first ionization energies, electronegativity’s and melting points for the alkali metals and halogens Characteristics Trend (descending Gr 1) Reason Atomic radius Increases - number of electron shells increase Ionic radius Increases - number of electron shells increase Electronegativi ty Decrease - attracting power of the nucleus is shielded by the inner electron shells Ionization energy Decrease - shielding effect of the inner electron shells increases Melting point Decrease - larger ions have weaker metallic bonding =>charge density is smaller Characteristics Trend (descending gr 7) Reason Atomic radius Increases - number of electron shells increase Ionic radius Increases - number of electron shells increase Electronegativi ty Decrease - attracting power of the nucleus is shielded by the inner electron shells Ionization energy Decrease - shielding effect of the inner electron shells increases Melting point increase - larger halogens have greater dispersion forces; holding molecules together 3.2.3 Describe and explain the trends in atomic radii, ionic radii, first
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
ionization energies and electronegativities for elements across period 3 Characteristic s Trend (left to right) Reasons Atomic radius Decreases in size Increase attractive force (acting on the same energy shell) of the nucleus increase as the # of protons increase Ionic radius Decrease until formation of negative ion which lead to sudden increase In general, as above. Sudden increase due to new (larger) outer shell Electronegativ ity Increases More e attracting power due to larger nuclear charge Ionization energy Increases Increase in nuclear charge Melting point Na => Al Steady increase Strong metallic bond More Delocalized electrons Si massive increase Giant macromolecular structure P large decrease P 4 molecules S mall increase S 8 crown shaped molecules
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 08/22/2011 for the course CHEMISTRY 101 taught by Professor Jameslee during the Three '09 term at Victoria AU.

Page1 / 7

Topic 3 Periodicity - Topic 3 Periodicity 3.2 physical...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online