Question

1. write the simple lewis - dot structure for each of the following atoms.

a. i (z = 53)
b. al (z = 13)
c. xe (z = 54)
d. sr (z = 38)

1. write the simple lewis - dot structure for each of the following atoms.

a. mg (z = 12)
b. br (z = 35)
c. s (z = 16)
d. si (z = 14)

1. write a lewis - dot structure for each of the following simple molecules. show all bonding valence electrons pairs as lines and all nonbonding valence electron pairs as dots.

a. h₂s
b. sif₄
c. c₂h₄
d. c₃h₈

1. write a lewis - dot structure for each of the following simple molecules. show all bonding valence electrons pairs as lines and all nonbonding valence electron pairs as dots.

a. c₂h₆
b. nf₃
c. c₄h₁₀
d. sicl₄

1. using the vsepr theory, predict the molecular structure of each of the following molecules.

a. cbr₄
b. ph₃
c. ocl₂
d. sicl₄

1. using the vsepr theory, predict the molecular structure of each of the following polyatomic molecules.

a. dihydrogen phosphate, h₂po₄⁻
b. perchlorate ion, clo₄⁻
c. sulfite ion, so₃²⁻

Explanation:

Step1: Determine valence electrons for atoms

For atoms, the number of valence electrons is determined by their group - number in the periodic table.
For Iodine (I, Z = 53), it is in Group 17, so it has 7 valence electrons. The Lewis - dot structure is I with 7 dots around it.
For Aluminum (Al, Z = 13), it is in Group 13, so it has 3 valence electrons. The Lewis - dot structure is Al with 3 dots around it.
For Xenon (Xe, Z = 54), it is in Group 18, so it has 8 valence electrons. The Lewis - dot structure is Xe with 8 dots around it.
For Strontium (Sr, Z = 38), it is in Group 2, so it has 2 valence electrons. The Lewis - dot structure is Sr with 2 dots around it.
For Magnesium (Mg, Z = 12), it is in Group 2, so it has 2 valence electrons. The Lewis - dot structure is Mg with 2 dots around it.
For Bromine (Br, Z = 35), it is in Group 17, so it has 7 valence electrons. The Lewis - dot structure is Br with 7 dots around it.
For Sulfur (S, Z = 16), it is in Group 16, so it has 6 valence electrons. The Lewis - dot structure is S with 6 dots around it.
For Silicon (Si, Z = 14), it is in Group 14, so it has 4 valence electrons. The Lewis - dot structure is Si with 4 dots around it.

Step2: Draw Lewis - dot structures for molecules

For \(H_2S\):

Sulfur is the central atom. Sulfur has 6 valence electrons and each hydrogen has 1 valence electron. The total number of valence electrons is \(6 + 2\times1=8\). Sulfur forms 2 single bonds with hydrogen atoms and has 2 non - bonding electron pairs. The Lewis - dot structure is \(H - S - H\) with 2 dots on the sulfur atom above and below it.

For \(SiF_4\):

Silicon is the central atom. Silicon has 4 valence electrons and each fluorine has 7 valence electrons. The total number of valence electrons is \(4+4\times7 = 32\). Silicon forms 4 single bonds with fluorine atoms and has no non - bonding electron pairs. The Lewis - dot structure is \(F - Si - F\) with \(F\) atoms above and below the \(Si\) atom, and no non - bonding electrons on \(Si\).

For \(C_2H_4\):

Each carbon has 4 valence electrons and each hydrogen has 1 valence electron. The total number of valence electrons is \(2\times4 + 4\times1=12\). There is a double bond between the two carbon atoms (\(C = C\)) and each carbon forms 2 single bonds with hydrogen atoms. The Lewis - dot structure is \(H_2C=CH_2\).

For \(C_3H_8\):

Each carbon has 4 valence electrons and each hydrogen has 1 valence electron. The total number of valence electrons is \(3\times4+8\times1 = 20\). The carbon atoms are in a chain (\(C - C - C\)) with each carbon forming the appropriate number of single bonds with hydrogen atoms to satisfy the octet rule.

For \(C_2H_6\):

Each carbon has 4 valence electrons and each hydrogen has 1 valence electron. The total number of valence electrons is \(2\times4+6\times1 = 14\). The two carbon atoms are bonded by a single bond (\(C - C\)) and each carbon forms 3 single bonds with hydrogen atoms. The Lewis - dot structure is \(H_3C - CH_3\).

For \(NF_3\):

Nitrogen has 5 valence electrons and each fluorine has 7 valence electrons. The total number of valence electrons is \(5 + 3\times7=26\). Nitrogen is the central atom, forms 3 single bonds with fluorine atoms and has 1 non - bonding electron pair. The Lewis - dot structure is \(F - N - F\) with \(F\) above the \(N\) and 2 dots on the \(N\) atom.

For \(C_4H_{10}\):

Each carbon has 4 valence electrons and each hydrogen has 1 valence electron. The total number of valence electrons is \(4\times4 + 10\times1=26\). The carbon atoms are in a chain (\(C - C - C - C\)) with each carbon forming the appropriate number of single bonds with hydrogen atoms to satisfy the octet rule.

For \(SiCl_4\):

Silicon has 4 valence electrons and each chlorine has 7 valence electrons. The total number of valence electrons is \(4+4\times7 = 32\). Silicon is the central atom, forms 4 single bonds with chlorine atoms and has no non - bonding electron pairs. The Lewis - dot structure is \(Cl - Si - Cl\) with \(Cl\) atoms above and below the \(Si\) atom, and no non - bonding electrons on \(Si\).

Step3: Predict molecular structures using VSEPR theory

For \(CBr_4\):

The central carbon atom has 4 bonding pairs and 0 non - bonding pairs. According to VSEPR theory, the molecular geometry is tetrahedral.

For \(PH_3\):

The central phosphorus atom has 3 bonding pairs and 1 non - bonding pair. According to VSEPR theory, the molecular geometry is trigonal pyramidal.

For \(OCl_2\):

The central oxygen atom has 2 bonding pairs and 2 non - bonding pairs. According to VSEPR theory, the molecular geometry is bent.

For \(SiCl_4\):

The central silicon atom has 4 bonding pairs and 0 non - bonding pairs. According to VSEPR theory, the molecular geometry is tetrahedral.

For \(H_2PO_4^-\):

The central phosphorus atom has 4 bonding pairs and 0 non - bonding pairs (after considering the charge). According to VSEPR theory, the molecular geometry is tetrahedral.

For \(ClO_4^-\):

The central chlorine atom has 4 bonding pairs and 0 non - bonding pairs (after considering the charge). According to VSEPR theory, the molecular geometry is tetrahedral.

For \(SO_3^{2 -}\):

The central sulfur atom has 3 bonding pairs and 1 non - bonding pair. According to VSEPR theory, the molecular geometry is trigonal pyramidal.

Answer:

a. I: Lewis - dot structure with 7 dots around I; \(H_2S\): \(H - S - H\) with 2 non - bonding pairs on S, tetrahedral electron - pair geometry and bent molecular geometry; \(CBr_4\): Tetrahedral molecular geometry
b. Al: Lewis - dot structure with 3 dots around Al; \(SiF_4\): \(F - Si - F\) with no non - bonding electrons on Si, tetrahedral molecular geometry; \(PH_3\): Trigonal pyramidal molecular geometry
c. Xe: Lewis - dot structure with 8 dots around Xe; \(C_2H_4\): \(H_2C=CH_2\), trigonal planar around each carbon; \(OCl_2\): Bent molecular geometry
d. Sr: Lewis - dot structure with 2 dots around Sr; \(C_3H_8\): Carbon - chain structure with appropriate single bonds to hydrogen; \(SiCl_4\): Tetrahedral molecular geometry
e. Mg: Lewis - dot structure with 2 dots around Mg; \(C_2H_6\): \(H_3C - CH_3\), tetrahedral around each carbon
f. Br: Lewis - dot structure with 7 dots around Br; \(NF_3\): \(F - N - F\) with 1 non - bonding pair on N, trigonal pyramidal molecular geometry
g. S: Lewis - dot structure with 6 dots around S; \(C_4H_{10}\): Carbon - chain structure with appropriate single bonds to hydrogen
h. Si: Lewis - dot structure with 4 dots around Si; \(SiCl_4\): Tetrahedral molecular geometry; \(H_2PO_4^-\): Tetrahedral molecular geometry
i. \(ClO_4^-\): Tetrahedral molecular geometry
j. \(SO_3^{2 -}\): Trigonal pyramidal molecular geometry