Theory - Unit 3 Bonding

Question 1

Bond Pairs

Answer 1

Pairs of electrons which form a bond.

Question 2

Lone Pairs

Answer 2

Electron pairs which are not involved in bonding. They do however, affect the shape because electron pairs repel other electron pairs.

Question 3

Rules for Writing Lewis Dot Structures

Answer 3

1. Total the Valence Electrons and Update during each step.
2. Form a single bond between the central atom and each surrounding atom (each bond uses two electrons).
3. Place electrons around the outer atoms until you run out or they each have eight electrons around them. (Hydrogen and Helium can only have two electrons around them).
4. Place any remaining electrons around the central atom.
5. Does each atom other than hydrogen have eight electrons around it?
6. Rearrange (share) electrons so that all atoms other than hydrogen have eight electrons around them.

Question 4

Octet Rule

Answer 4

All atoms other than hydrogen and helium bond to fill their valence shell with eight electrons.

Question 5

Duet Rule

Answer 5

Hydrogen bonds to fill it’s valence shell with two electrons. Helium already has two electrons and thus does not need to form bonds to increase stability.

Question 6

Violations of the Octet Rule

Answer 6

Be - 4

B - 6

P - 8 or 10

S - 8, 10, or 12

Xe - 8, 10, or 12

Question 7

VSPER

Answer 7

Valence Shell Electron Pair Repulsion

Most important aspect of determining the shape or geometry of a molecule. The molecule will adopt the shape which minimizes te electron pair repulsion.

Question 8

What is the Lewis dot structure of Br₂?

Question 9

What is the Lewis dot structure of XeF₄?

Question 10

What would the Lewis dot structure of OC be?

Question 11

Hydrogen

Answer 11

Group 1 Nonmetal

Question 12

Ionic Bond

Answer 12

Metals GIVE electrons, Nonmetals TAKE electrons

Question 13

Naming Ionic Bonds

Answer 13

State the name of the metal followed by the nonmetal with the ending changed to “ide”. If the metal is a transition metal, add a (Roman numeral). AlCl₃ = Aluminum Chloride CuCl₃ = Copper (III) Chloride

Question 14

Writing Formulas for Ionic Bonds

Answer 14

Absolute Value Criss Cross Oxidation #’s

Question 15

Polyatomic Ion

Answer 15

A group of atoms that acts like an ion (has a charge)

Question 16

Properties of Ionic Compounds

Answer 16

Crystalline Structure High Melting Point Rigid Strong Bond Conduct Electricity (when dissolved or melted) Good Insulators

Question 17

Covalent/Molecular Bonding

Answer 17

Nonmetals SHARE electrons

Question 18

Intermolecular Forces

Answer 18

Attractive forces BETWEEN molecules.

Van Der Waals or London Dispersion Forces are the weakest type of intermolecular force and hydrogen bonds are the strongest.

Question 19

Intramolecular Forces

Answer 19

Attractive forces WITHIN a molecule (Ionic & Covalent Bonds)

These bonds are stronger than intermolecular forces.

Question 20

Polar Covalent

Answer 20

A type of covalent bond between two atoms in which electrons are shared unequally. Because of this, one end of the molecule has a slightly negative charge and the other a slightly positive charge.

Question 21

Non Polar Covalent

Answer 21

A type of covalent bond between two atoms in which electrons are shared equally.

Question 22

Naming Covalent Compunds

Answer 22

You DO NOT use the “criss-cross” method. Use prefixes. The only time you do not use a prefix is when there is only one of the first nonmetal. Remember : 1-Mono 2-Di etc…

Question 23

Write the formula for Mg²⁺ and PO₄³⁻

Answer 23

Using the criss-cross method and subscripts to insure sum of charges is zero: Mg₃(PO₄)₂

Question 24

Polyatomic Ionic Formulas

Answer 24

1. Metal written first, Polyatomic Ion is written second 2. Use criss-cross method and subscripts to insure sum of charges = 0 3. When using a subscript for polyatomic ions: place a parentheses around the polyatomic formula, put the subscript outside of the parentheses

Question 25

Polyatomic Ion

Answer 25

Polyatomic Ions ions made up of more than one atom; acts as an individual ion in a compound; charge applies to entire group of atoms.

Question 26

Ionic Compounds

Answer 26

two words, first names cation second names anion. Indicate charge of transition metal cation by Roman Numeral. MgCl₂ = Magnesium Chloride Cr(NO₃)₃ = Chromium(III) Nitrate SnCl₂ = Tin(II) Chloride

Question 27

Anions

Answer 27

Anions are named by adding the suffix -ide to the stem of the name of the nonmetal from which they are derived. N³⁻ = Nitride O²⁻ = Oxide F⁻ = Flouride

Question 28

Ionic Compound Formulas

Answer 28

1. Metal written first Nonmetal written second 2. Use criss-cross method and subscripts to insure sum of charges = 0

Question 29

Oxidation Number

Answer 29

Ion Charge - number of electrons transferred to or away from an atom when it becomes an ion.

Question 30

Greek Prefixes used in nomenclature 1= 2 = 3 = 4= 5 = 6= 7= 8= 9= 10=

Answer 30

1= mono 2 =di 3 =tri 4=tetra 5 = penta 6=hexa 7=hepta 8=octa 9=nona 10=deca

Question 31

Covalent or Molecular Compounds (Molecules)

Answer 31

The first word gives name of the element that appears first preceded by a prefix that shows number of atoms in that element. Do NOT use the prefix mono before the name of the first element. The second word consists of a prefix designating the number of atoms of that element, the stem name of the second element, and the suffix -ide.

Question 32

(Oxidation #) Charge of Group17 or 7A (F, Cl, Br, I)

Answer 32

Charge: 1-

Question 33

(Oxidation #) Charge of Group 16 or 6A (O,S, Se, Te):

Answer 33

Charge: 2-

Question 34

Charge of Group15 or 5A (N, P, As):

Answer 34

Charge = 3-

Question 35

(Oxidation #) Charge of Group 2 or 2A (Be, Mg, Ca, Sr, Ba):

Answer 35

Charge = 2+

Question 36

(Oxidation #) Charge of Group 1 or 1A (H, Li, Na, K, Rb, Cs):

Answer 36

Charge = 1+

Question 37

Ionic Compounds

Answer 37

Conduct Electricity when melted or dissolved in water because....

Question 38

Compound Formation

Answer 38

Compounds are the result of the formation of chemical bonds between two or more different elements, whose atoms lose, gain or share valence electrons to complete their outer shell and attain a noble gas configuration. This tendency of atoms to have eight electrons in their outer shell is known as the octet rule.

Question 39

Summarize the rules for naming ionic and covalent compounds.

Answer 39

Question 40

Summarize how to write formulas for ionics and covalents.

Answer 40