JeopardyLabs

electron/molecular geometry

100

Number of electron domains in ethanol (C₂H₅OH) on the a carbon atom

4

Ethanol consists of a chain of 2 carbon atoms bonded by single bonds (sharing of 2 electrons) and one of the carbon atoms has single bonds with 3 hydrogens and the other carbon atom has 2 single bonds with hydrogen and a single bond with oxygen (that has a final hydrogen bonded to the O). There is a total sharing of 20 electrons (2(4)+6(1)+6=20e^-) and the 8 single bonds along with the 2 lone pairs on oxygen obeys that number of electrons (2(8)+2(2)=20) and minimizes all formal charges to 0.

200

# of lone pairs are on N in NH3

1 lone pair 

3xH + N = 3(1) + 5 = 8 valence electrons

One single bond on each H and to balance formal charge of N, add a lone pair:

formal charge:

       H   H  H  N

ve    1  1   1   5

ae    1  1   1   5

fc  = 0  0  0   0  

300

Electron and Molecular Geometry for CH4

Both electron geometry and molecular geometry is tetrahedral because there are 4 electron domains around the Carbon atom with no lone pairs.

valence electrons = 4H + C = 4(1) + 4 = 8ve

4 single bonds from C to H balances all formal charges:

formal charge:

      H  H  C  H  H

ve   1  1   4  1  1

ae   1  1   4   1  1

fc  = 0 0  0   0  0

400

Molecular Geometry for Water

Bent because there are 2 lone pairs and 2 bonding pairs (total electron domain of 4)

valence electrons: 2H + O = 2(1) + 6 = 8ve

formal charge:

       H  H  O

ve    1  1   6

ae    1  1   6

fc  = 0  0   0 

500

Is SO2 polar or nonpolar?

SO2 is polar 

Oxygen is more electronegative than Sulfur, so Sulfur is the central atom. Sulfur has 6 valence electrons in the 3rd shell (1s²2s²2p⁶3s²3p⁴), so it shares 2 electrons with both Oxygens in each bond. BUT in order to reduce formal charges on the oxygens, S will have double bonds with both oxygens (so the central atom S will have 4 electrons). S needs to have 6 valence electrons for the correct lewis structure so it will have one lone pair and both oxygens will have two lone pairs. This bent molecular geometry resulting from a lone pair being one of the electron domains results in dipole movement (an uneven distribution/sharing of electrons--> SO2 is a polar

Electron configuration

100

Electron configuration for K

1s²2s²2p⁶3s²3p⁶4s

Potassium is the first element in the 4th row of the periodic table of elements. It also has 18 protons, and since an element yields no charge (is neutral), then there are also 18 electrons, so the total number of electrons represented in the e config. is consistent with the number of electrons K has. The s orbital can only have 2 electrons max. and the p subshell can only have 6 electrons max. and the e config. is consistent with that as well because the electrons written for each orbital never exceeds its maximum capacity.

200

Electron configuration for P

1s²2s²2p⁶3s²3p³

Potassium is the 5th element in the 3rd row, so there are 2 valence electrons in the s orbital (as written 3s²) and 3 valence electrons in the p orbital (as written 3p³). The # of electrons is also consistent with the number of electrons P has (15 protons --> 15 electrons & 2+2+6+2+3=15e^- from the e config.)

300

Electron configuration for Al

1s²2s²2p⁶3s²3p

Aluminium has 3 valence electrons in its 3rd shell as shown on the periodic table. But since only 2 electrons can go into the s orbital (3s²), the final valence electron is in the p orbital (3p). The e config. is also consistent with the # of electrons Al has (atomic # is 13 --> 13 protons --> 13 electrons b/c Al element is neutral)

400

Electron configuration for iodide ion

1s²2s²2p⁶3s²3p⁶4s²4p⁵

Iodide is the anion for iodine. Iodine is in the 5th row of the periodic table of elements and has 53 protons, so also 53 electrons. However, the ion of iodine is formed by the element gaining 1 electron --> 53e^- + 1e^- = 54e^-. The e config. is consistent with this # of electrons and to write it, you would write the normal configuration for the element iodine but change 4p⁴ --> 4p⁵ because there is 1 more electron in that p orbital and the p orbital hasn´t reached its max capacity of 6 electrons.

500

Electron configuration for Mg cation

1s²2s²2p⁶

Mg is the second element in the 3rd row; it has 12 protons-->12 electrons which is consistent with the e config. of Mg (1s²2s²2p⁶3s²). However, the ion of Mg is formed by losing 2 electrons, so 3s^2-2=0, so Mg²⁺ no longer has valence electrons its 3rd shell, so the new e config. is just 1s²2s²2p⁶ with its 2 shell completely filled with electrons (both s and p orbital).

hybridization

100

Hybridization of CF⁴

sp³

There are 4 electron domains (4 single bonds b/w C and F), so there are 4 "levels" (s + 3 p's = 4)

200

Hybridization of CH₄

sp³

There are 4 electron domains (4 single bonds b/w C and H), so when the orbitals are put together to form a hybrid orbital, it would be sp³ because there are 4 ¨levels¨ of bonding and sp³ is consistent with that because 1_s + 3_p = 4 domains of bonding.

300

Hybridization of CO₂

sp

CO₂ has 2 electron domains. There are 2 double bonds b/w C and O --> 2 levels of hybridization --> sp

400

Hybridization of H₂O

sp³

H₂O has 4 electron domains (2 single bonds b/w O and H and 2 lone pairs on the central atom O) --> 3 "levels" of hybridization --> sp³

500

Hybridization of NO₃^-

sp²

NO₃^- has 3 electron domains (1 double bond(sigma and pi) & 2 single/sigma bonds) --> 3 levels of hybridization --> sp²

Find the element

100

The element with an electron configuration of 1s²2s²2p⁴

Oxygen

200

The element with an electron configuration of 1s²2s²2p6

Neon

300

The element with an electron configuration of 1s²2s²2p⁶3s²3p²

Silicon (it has 14 protons so it also has 14 electrons; the configuration also shows 2 electrons in the s orbital and 2 in the p orbital of the 3rd shell, meaning it has 4 total valence electrons, so the configuration is of the element on the 3rd row and 4 elements to the right of the periodic table)

400

The element with an electron configuration of 1s²2s

Lithium (it has 3 protons so it also has 3 electrons to make the element neutral, so it has 2 in the first shell, and 1 valence electron in its outermost shell (the 2nd shell))

500

The element, anion, and cation with an electron configuration of 1s²2s²2p⁶

Element: Neon (because it has 8 valence electrons in its 2nd shell; 2nd row, last column)

Cation: Mg (because Mg's ion has a 2+ charge, it loses 2 electrons; 12e^--2e^-=10e^-, and therefore has 8 valence electrons in it outermost shell when originally it had 2 valence electrons in its 3rd shell)

Anion: Oxygen (because its charge is 2-, it will gain 2 electrons, so its original electron configuration is 1s²2s²2p⁴ because it has electrons filling its first shell and 6 valence electrons in its second shell; once it gains 2 electrons, it will have 8 valence electrons (2 in the s orbital and 6 in the p orbital))