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Lesson: Lewis Structures

In this lesson, we will learn how to draw Lewis structures of compounds from their names or formulas and how to count the numbers of lone and valence electrons.

Worksheet • 18 Questions

Q1:

Which one of the following is the correct Lewis structure of O H – ?

  • A
    O – H
  • B
    O H
  • C
    O H
  • D
    O H
  • E
    O H

Q2:

Which of the following is the correct Lewis structure for G a ?

  • A G a
  • B G a
  • C G a
  • D G a
  • E G a

Q3:

In the Lewis structure shown, X and Y represent different elements and all valence electrons of the atoms are shown. The molecule is stable and neutral, and Y is an element in the second period of the periodic table.

X X Y X

What is the chemical symbol of element X ?

  • A H
  • B F
  • C H e
  • D B e
  • E L i

What is the chemical symbol of element Y ?

  • A N
  • B F
  • C B
  • D O
  • E C

Q4:

Which of the following is not a step taken when drawing out a Lewis structure?

  • ALine the atoms up according to their atomic masses.
  • BCount the valence electrons.
  • CProduce octets of electrons by rearranging the electrons to form multiple bonds.
  • DAdd electrons to the outside atoms.
  • EPlace the leftover electrons on the central atom.

Q5:

In the reaction equation, what does the dot next to the sodium indicate?

+ sodium atom sodium cation Na Na + e –
  • AIt has a lone electron: it is a free radical.
  • BIt is bonded to another, small atom.
  • CIt is unstable.
  • DIt is negatively charged.
  • EIt is positively charged.

Q6:

Which one of the following is the correct Lewis structure of P H 3 ?

  • A
    P H H H
  • B
    P – H H H
  • C
    P + H H H
  • D
    P H H H
  • E
    P H H H

Q7:

Which of the following is the correct Lewis structure for A s 3 – ?

  • A
    As 3 –
  • B
    As
  • C
    As
  • D
    As 3 –
  • E
    As 3 –

Q8:

In Lewis diagrams, what does each dot represent?

  • AA single outer-shell electron
  • BA single inner-shell electron
  • CA single positive charge
  • DA pair of electrons

Q9:

Which of the following is the correct Lewis structure for C l B B C l 2 2 ?

  • A
    B Cl B Cl Cl Cl
  • B
    B Cl Cl B Cl Cl
  • C
    B Cl Cl B Cl Cl
  • D
    B Cl B Cl Cl Cl
  • E
    B B Cl Cl Cl Cl

Q10:

Which one of the following is the correct Lewis structure of H C l ?

  • A
    H Cl
  • B
    H Cl
  • C
    H Cl
  • D
    H Cl
  • E
    H Cl

Q11:

In the reaction equation, what do the two dots on the calcium atom indicate?

+ calcium atom calcium cation Ca Ca 2 + 2 e –
  • AIt has two lone electrons, in separate orbitals: it is a diradical.
  • BIt has a lone pair of electrons.
  • CIt is unstable.
  • DIt is negatively charged.
  • EIt is positively charged.

Q12:

Which one of the following is the correct Lewis structure of S O 3 ?

  • A
    S O O O
  • B
    S O O O
  • C
    S O O O
  • D
    S O O O
  • E
    S O O O

Q13:

Which one of the following is the correct Lewis structure of I 3 – ?

  • A
    I – I I
  • B
    I I I
  • C
    I I I
  • D
    I – I I
  • E
    I I – I

Q14:

Nitrous oxide ( N O ) 2 , commonly known as laughing gas, is used as an anesthetic in minor surgeries, such as the routine extraction of wisdom teeth. Including lone pairs, give the structural formula of nitrous oxide.

  • A
    O N N
  • B
    N N O

Q15:

The Lewis dot structure for a sulfate ion gives sulfur a formal charge of zero with six bonds. Based on the structure and the Lewis dot theory, which of the following statements about the sulfur atom is false?

O S 2 – O O O
  • ASulfur has more valence electrons than oxygen.
  • BThe sulfur disobeys the octet rule.
  • CSulfur is less electronegative than oxygen.
  • DSulfur has a greater number of electron shells than oxygen.

Q16:

Which of the following is the correct Lewis structure for a monomer of G a C l 3 ?

  • A
    Ga Cl Cl Cl
  • B
    Ga Cl Cl Cl
  • C
    Ga Cl Cl Cl
  • D
    Ga Cl Cl Cl
  • E
    Ga Cl Cl Cl

Q17:

Which one of the following is the correct Lewis structure of B ( O H ) 3 ?

  • A
    B O O O H H H
  • B
    B O O O H H H
  • C
    B O O O H H H
  • D
    B O O H H H O
  • E
    B H H H O O O

Q18:

Which one of the following is the correct Lewis structure of C O 2 ?

  • A
    C O O
  • B
    O C O
  • C
    C O O
  • D
    O O C
  • E
    C O O
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