Periodic Trends HW 8-10 and 8-11

Which atom is biggest? Which is smallest? Compare: Li, #3, Ne, #10, Na, #11 What particles make up atoms? How many does each element have? Predict which element you think would be biggest and which would be smallest. Video link atomic radius

3 10 11 4 10 12 3 10 11 7 Li 3 20 Ne 10 23 Na 11 p: n: e-: p: n: e-:

Size of an atom is determined by size of electron cloud

Li Ne Na 71 pm 152 pm 186 pm

Why is Ne smaller than Li? +3 Li +++

Why is Ne smaller than Li? +3 +10 Li +++ Ne ++++++++++

Why is Ne smaller than Li? +3 +10 Li +++ Ne ++++++++++ INCREASING THE NUMBER OF PROTONS INCREASES THE ATTRACTION FOR THE VALENCE ELECTRONS OF THE SAME ENERGY LEVEL

Atomic Radius

Why is Na bigger than Ne? Na: 1s22s22p6 3s1 Ne: 1s22s22p6

Why is Na bigger than Ne? SODIUM HAS AN EXTRA ENERGY LEVEL Na: 1s22s22p6 3s1 Ne: 1s22s22p6 SODIUM’S VALENCE ELECTRON IS IN LEVEL 3; Ne’s VALENCE ELECTRONS ARE IN LEVEL 2 SODIUM HAS AN EXTRA ENERGY LEVEL

K Na Li Li Ar Ne

In the periodic table, vertical columns are called groups or families…

… while the horizontal rows are called periods.

HW 8-11 Li: [He]2s1 Na: [Ne]3s1 K: [Ar]4s1 As we move down a family, an extra energy level is added. The higher the energy level of the valence electrons, the farther the average distance from the nucleus and the larger the atom.

Atomic Radius (AR) Make a QUICK sketch of this picture in the box. Atomic Radius Animation

Atomic Radius Across a period, atomic radius decreases. Reason: More protons pull on electrons which are in orbitals with similar energies.

Atomic Radius Down a group, atomic radius increases. Reason: Elements have electrons in higher energy orbitals, which are farther from the nucleus.

Rank the following from largest AR to smallest. 1) Na, K, Rb Answer: Rb > K > Na Reason: Down a family, radius ↑ 2) Na, Si, S Answer: Na > Si > S Reason: Across a period radius ↓

Rank the following from largest AR to smallest. 3) N, P, As Answer: As > P > N Reason: Down a family, radius ↑ 4) N, O, F Answer: N > O > F Reason: Across a period radius ↓