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1. Kr
Draw the Lewis dot structure for Kr. To change the symbol of an atom, dou- ble-click on the atom and enter the letter of the new atom.: 8 E Kr Correct In the Lewis model, the valence electrons of main-group elements are represented as dots surrounding the symbol of the element. Each dot represents a valence electron. You place the dots around an element's symbol with a maximum of two dots per side. Kr has the electron configuration n [Ar]4s2 4p6. Therefore, Kr has eight valence electrons.
2. P
Draw the Lewis dot structure for P.: 5 E FOR P Spread them around the atom and then double up. Correct P has the electron configuration [Ne] 3s2 3p3. Therefore, P has five valence electrons.
3. B
Draw the Lewis dot structure for B. To change the symbol of an atom, dou- ble-click on the atom and enter the letter of the new atom.: Correct B has the electron configuration [He] 2s2 2p1. Therefore, B has three valence electrons.
4. Na
Draw the Lewis dot structure for Na. To change the symbol of an atom, double-click on the atom and enter the letter of the new atom.: 1 e for na Correct NaNa has the electron configuration [Ne]3s1[Ne]3ý1. Therefore, NaNa has one valence electron.
5. For each of the following ions, indicate the noble gas that has the same Lewis structure as the ion.
Se Express your answer as a chemical symbol.: Kr
6. For each of the following ions, indicate the noble gas that has the same Lewis structure as the ion.
I: Xe
7. For each of the following ions, indicate the noble gas that has the same Lewis structure as the ion.
Sr2+: Kr because Sr2+ indicates an Sr ion that has lost 2 E making it have the same # of Es as Kr
8. For each of the following ions, indicate the noble gas that has the same Lewis structure as the ion.
F: Ne
9. The sharing of electrons occurs when two nonmetals form a compound with a covalent bond. When a metal and a nonmetal
combine to create a compound, the transfer of electrons generates an ionic bond.:
10. Draw a Lewis structure for each of the following molecules.
CH
Draw the molecule by placing atoms on the grid and connecting them with bonds. Include all lone pairs of electrons.: The sharing of electrons between ele- ments generates the compound CH4, thus forming covalent bonds. Four hydrogen atoms each share one electron with carbon to create stable outer shells for all atoms.
11. Draw a Lewis structure for each of the following molecules.
NF3: The sharing of electrons between elements generates the compound NF3NF3, thus forming covalent bonds. One nitrogen atom shares one electron with each of the three fluorine atoms to form stable outer shells for all atoms.
12. Draw a Lewis structure for each of the following molecules.
OF3: Correct The sharing of electrons between elements generates the compound OF2OF2, thus forming covalent bonds. One oxygen atom shares one electron with each of the two fluorine atoms to form stable outer shells for all atoms.
13. Draw a Lewis structure for each of the following molecules.
H2O
Draw the molecule by placing atoms on the grid and connecting them with bonds. Include all lone pairs of electrons.: The sharing of electrons between elements generates the compound H2OH2O, thus forming covalent bonds. One
= 16 tot Distribute electrons among the atoms, giving octets to as many atoms as possible. If any atoms lack an octet, as they do in this case, form double bonds as necessary to give them octets. Recall that electron groups are lone pairs, single bonds, or multiple bonds. SiO2 has the following structure: The central atom has two bonding groups and no lone pairs. Therefore, the molecular geometry is linear.:
21. Determine the molecular geometry of each of the following molecules. BF3: trigonal planar
22. Correct
BF3 contains 24 electrons: total number of electrons for Lewis structure = (#valenceeforB) + (#valencee - forF) = 3 + 3(7) = 24 Distribute electrons among the atoms, giving octets to as many atoms as possible. A significant exception to the octet rule is boron, which tends to form compounds with only six electrons around the central BB atom. Recall that electron groups are lone pairs, single bonds, or multiple bonds. BF3 has the following structure: The central atom has three bonding groups and no lone pairs. Therefore, the molecular geometry is trigonal planar.:
23. Determine the molecular geometry of each of the following molecules. CFCl3 (Note that carbon is the central
atom.): tetrahedral
24. Correct
CFCl3 contains 24 electrons: totalnumberofelectronsforLewisstructure = (#valenceeforC)+(#valencee - forF)+(#valenceeforCl) = 4+7+3(7) = 32 Distribute electrons among the atoms, giving octets to as many atoms as possible. Recall that electron groups are lone pairs, single bonds, or multiple bonds. CFCl3 has the following structure:
The central atom has four bonding groups and no lone pairs. Therefore, the molecular geometry is tetrahedral.:
25. Determine the molecular geometry of each of the following molecules. H2CSH2CS (Note that carbon is the
central atom): trigonal planar
26. Correct
H2CS contains 12 electrons: totalnumberofelectronsforLewisstructure = (#valenceeforH)+(#valencee - forC)+(#valenceeforS) = 2(1) + 4 + 6 = 12 Distribute electrons among the atoms, giving octets (or duets for hydrogen) to as many atoms as possible. If any atoms lack an octet, as in this case, form double or triple bonds as necessary to give them octets. Recall that electron groups are lone pairs, single bonds, or multiple bonds. H2CSH2CS has the following structure: The central atom has three bonding groups and no lone pairs. Therefore, the molecular geometry is trigonal planar.:
