Periodic Trends

Half of the distance between two bonding atoms nuclei Atomic Radius Half of the distance between two bonding atoms nuclei

Atomic Radius Trend Increases Increases

Atomic Radius Across a Period Atomic radius generally decreases in size as you move left to right across the period Increasing positive charge in the nucleus pulls the electrons of the same energy level in.

Atomic Radius Down a Group Atomic radius increases as you move down a group Orbital size increases as you move down a group with increasing energy level Larger orbitals means that outer electrons are farther from the nucleus. This increased distance offsets the greater pull of the increased nuclear charge. As additional orbitals between the nucleus and the outer electrons are occupied, the inner electrons shield the outer electrons from the pull of the nucleus this is called shielding.

Shielding The inner electrons shield the outer electrons from feeling the pull of the nucleus

Ionic Radius Compare ions to their neutral counterparts Ion: charged atom that results from the gaining or losing of electrons Cation: loses electrons and produces a positive charge Anion: gains electrons and produces a negative charge

Octet Rule Atoms gain, lose, or share electrons to acquire a full set of eight valence electrons (to be like a noble gas) Eight is great!!!

Cations and Anions Of Representative Elements +1 +2 +3 -3 -2 -1

Cation vs Atom

Cation Atom 12 electrons 10 electrons Mg2+ Mg Magnesium Cation 12 protons 12 electrons 12 protons 10 electrons Mg2+ Magnesium Cation Mg Magnesium Atom

Anion vs Atom

Anion Atom 18 electrons 16 electrons S Sulfur Atom S2- Sulfer Anion 16 protons 18 electrons 16 protons 16 electrons S Sulfur Atom S2- Sulfer Anion

Cation is always smaller than atom from which it is formed. Anion is always larger than atom from which it is formed.

Isoelectronic have the same number of electrons, and hence the same ground-state electron configuration N3-: 1s22s22p6 or [Ne] O2-: 1s22s22p6 or [Ne] F-: 1s22s22p6 or [Ne] Na+: 1s22s22p6 or [Ne] Al3+: 1s22s22p6 or [Ne] Na+, Al3+, F-, O2-, and N3- are all isoelectronic with Ne

Periodic Table video

WUP#14 For the element Br find the following: Electron configuration Excited state Noble gas configuration Orbital diagram

Periodic Trends day 2

Ionization Energy Minimum energy required to remove an electron from a gaseous atom in its ground state Indication of how strongly an atom’s nucleus holds onto its valence electron

What do you notice between successive ionization energies What do you notice between successive ionization energies? What is the trend across and down?

General Trends in First Ionization Energies Increasing First Ionization Energy Increasing First Ionization Energy

Ionization Energy Trends – Across a Period Ionization energy generally increases as you move left to right, including noble gases Across a period electrons are added to the same energy level (same distance away from the nucleus), yet the nuclear charge is increasing across a period increasing the attraction to the electrons.

Ionization Energy Trends – Down a Group Ionization energy decreases as you move down a group Down a group electrons are added to a higher energy level (farther distance away from the nucleus), making it easier to remove an electron

Electronegativity Indicates an element’s ability to attract electrons in a shared chemical bond fluorine (F) is the most electronegative element cesium (Cs) and francium (Fr)are the least electronegative Noble gases do not tend to have an electronegativity number since they tend not to form compounds

F > O > Cl, N > Br > C, S > I > H , P Electronegativity Memorize! F > O > Cl, N > Br > C, S > I > H , P Frank Owes Claire Nine Brownies Cause She Isa Hungry Person *elements w commas between are = E.N.

Trends with Electronegativity Electronegativity increases as you move left-to-right across a period Electronegativity decreases as you move down a group