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

Transcription

1 Periodic Trends

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

3 Increases Atomic Radius Trend Increases

4 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.

5 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.

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

7 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

8 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!!!

9 +1 +2 Cations and Anions Of Representative Elements

10 Cation vs Atom

11 Atom 12 electrons 12 protons Cation 10 electrons 12 protons Mg Magnesium Atom Mg 2+ Magnesium Cation

12 Anion vs Atom

13 Atom 16 electrons 16 protons Anion 18 electrons 16 protons S Sulfur Atom S 2- Sulfer Anion

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

15 Isoelectronic have the same number of electrons, and hence the same ground-state electron configuration N 3- : 1s 2 2s 2 2p 6 or [Ne] F - : 1s 2 2s 2 2p 6 or [Ne] O 2- : 1s 2 2s 2 2p 6 or [Ne] Na + : 1s 2 2s 2 2p 6 or [Ne] Al 3+ : 1s 2 2s 2 2p 6 or [Ne] Na +, Al 3+, F -, O 2-, and N 3- are all isoelectronic with Ne 15

16 Periodic Table video

17 WUP#14 For the element Br find the following: 1. Electron configuration 2. Excited state 3. Noble gas configuration 4. Orbital diagram

18 Periodic Trends day 2

19 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

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21 Increasing First Ionization Energy General Trends in First Ionization Energies Increasing First Ionization Energy 21

22 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.

23 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

24 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

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26 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.

27 Trends with Electronegativity Electronegativity increases as you move leftto-right across a period Electronegativity decreases as you move down a group