Unit 2: Covalent bonds & Lewis Dot Structure

Question 1

Resonance Structure

Answer 1

two different valid Lewis dot structures with slightly different electron distribution

Question 2

Ionic Compounds are nearly always composed of

Answer 2

metals bound to nonmetals.

Question 3

Lewis dot structure shows

Answer 3

a simple representation of the valence electrons which surround an element

Question 4

When elements come together to form bonds they share

Answer 4

as many electrons as needed for each side to have a full electronic shell

Question 5

Some compounds share more than just two pairs of electrons, but the maximum that can be shared is

Answer 5

6 electrons (or 3 pairs)

Question 6

Steps for writing simple and complex covalent molecules

Answer 6

1 - Count the total number of valence electrons available. This is the sum of the valence electrons in each of the atoms bonding. If the structure is that of an ion, then remove or add a number of electrons equal to the ion charge.
2 - Arrange the atoms in order of connectivity (unless otherwise noted or if it is hydrogen, the FIRST atom listed is the central atom).
3 - Connect the central atom with a single bond to each exterior atom (two shared electrons).
4 - Distribute the remaining electrons like so: A - Add electrons to each exterior atom so they each have a total of 8 (2 if hydrogen).B - Add any remaining electrons to the interior atom.
5 - Evaluate your structure to ensure that all atoms have a full shell. If they do not, share moreelectrons by forming double and/or triple bonds by bringing in electrons from exterior atoms.(Repeat this step until all atoms have a full shell)

Question 7

VSEPR

Answer 7

is the model we use to predict molecular shape

Question 8

The basis of Valence Shell Electron Pair Repulsion theory is the understanding that

Answer 8

like charges repel one another.

Question 9

Because like charges repel one another, multiple electron sets in a covalent molecule will arrange themselves in

Answer 9

a 3-dimensional space to be as far apart from one another as possible while still connected to the central atom.

Question 10

the shape of simple covalent compounds is determined by

Answer 10

electron sets around a central atom

Question 11

What qualifies as one electron set?

Answer 11

a lone pair, a single bond, a double bond, or a triple bond (3)

Question 12

Why do we consider a double bond to be only one electron set even though there are 4 electrons in it?

Answer 12

a double bond, of necessity, must occupy the same (or similar) space as the single bond

Question 13

electronic geometry of a molecule

Answer 13

the geometric arrangement in space of the electrons surrounding the central atom

Question 14

geometric shape of two electron sets

Answer 14

Linear; 180º angle

Question 15

geometric shape of three electron sets

Answer 15

trigonal planar; “a triangle in the same plane”; 120 º angle.

Question 16

geometric shape of four electron sets

Answer 16

tetrahedral, or four sided structure, 109.5º angle

Question 17

What is used to demonstrate a 3D structure?

Answer 17

standard wedge-and-dash notation to solve this problem. The wedge is a bond coming out of the screen towards you and a dash is a bond going into the screen away from you

Question 18

molecular geometry tells us

Answer 18

the geometric arrangement of the atoms connected with the central atom.

Question 19

any structure with no lone pairs of electrons has the same

Answer 19

molecular and electronic geometry

Question 20

A molecule with two electron sets is always

Answer 20

linear.

Question 21

Depending on the number of atoms attached to it, a molecule with three electron sets is either

Answer 21

trigonal planar or bent

Question 22

four electron set determining factors

Answer 22

the central atom can be attached to four atoms, to three atoms and one lone pair, or to two atoms and two lone pairs

Question 23

three electron set determining factors

Answer 23

either the central atom can be attached to three atoms, or to one lone pair and two atoms.

Question 24

Depending on the number of atoms attached to it, a molecules shape with four electron sets is

Answer 24

tetrahedral, trigonal pyramidal, or bent.

Question 25

Properties of molecular compounds

Answer 25

Covalent, smallest components are always neutral, usually composed of nonmetal-nonmetal, low melting and boiling point (which means a gas at room temperature) **do not usually conduct electricity if it is not a metal.

Question 26

The smallest possible unit of a covalent compound is a(an)

Answer 26

molecule

Question 27

Properties of an ionic compound

Answer 27

conducts electricity when dissolved in water or is melted, composed of a metal-nonmetal