Unit A:The Diversity Of Matter And Chemical Bonding:Bonding

Question 1

Bonding

What’s a chemical bond?

Answer 1

A force of attraction that holds atoms together in a crystal or molecule, leading to the sharing or transfer of electrons.

Question 2

Bonding

What’s the octet rule?

Answer 2

A rule that predicts if bonds will form between specific elements or atoms and the type of bonds that will form. This excludes hydrogen because it only has two electrons. When this occurs, a chemical bond is formed.

Question 3

Electron Dot(Lewis Dot) Diagrams
What is an electron dot diagram? Draw one.

Answer 3

Consists of the chemical symbol for the element with Dots representing the valence electrons. 
Ex:
    ¨
 · O : -Lone pair
    . -Bonding Electron

Question 4

Electron Dot(Lewis Dot) Diagrams
What are lone pairs?

Answer 4

Where two electrons are paired on an element.

Question 5

Electron Dot(Lewis Dot) Diagrams
What are bonding electrons?

Answer 5

When an electron is found all by itself(it is where an electron will be gained, shared or lost).

Question 6

Ionic Compounds

What are ionic bonds?

Answer 6

A force of attraction that holds ions together as a result of a transfer of electron(s), forming a structure called a crystal lattice.

Question 7

Properties of Ionic Commpounds

What are the properties of ionic compounds?

Answer 7

• Ionic compounds are solids at room temperature and have high melting points
• solutions(when mixed in water) of ionic compounds will conduct electricity
• All ionic compounds dissolve in water to some extent, because ions are attracted to water molecules
• Compounds retain crystal lattice shape even when broken into smaller parts.
• Strong attraction between ions holds the ions in a tight crystal lattice

Question 8

Use an electron dot diagram to show electron transfer for the formation of sodium chloride.

Answer 8

Electron Transfer
             ¨
=Na·»  ·Cl:  
             ¨
        ¨
=Na:Cl:
        ¨

Question 9

Covalent Bonding-Molecular Substances

What is a covalent bond?

Answer 9

A covalent bond is a force of attraction that holds non-metals together as a result of a simultaneous attraction of two nuclei for a shared pair of electrons forming a structure called a molecule.

Question 10

Covalent Bonding-Molecular Substances

What are the properties of molecular compounds?

Answer 10

• can be solid liquid or gas at room temperature
• doesn’t form irons in a solution
• doesn’t conduct electricity in solution

Question 11

Covalent Bonding-Molecular Substances

What are single bonds?

Answer 11

When one pair of electrons is shared between two atoms so that each atom fills its valence shell.

Question 12

Covalent Bonding-Molecular Substances

What are double bonds?

Answer 12

When two pairs of electrons are shared between two atoms so that each atom fills its valence shell.

Question 13

Covalent Bonding-Molecular Substances

What are triple bonds?

Answer 13

When three pairs of electrons are shared between two atoms so that each atom fills its valence shell.

Question 14

Covalent Bonding-Molecular Substances

What are structural diagrams?

Answer 14

Use a line to represent where a pair of electrons are being shared between two atoms. Electron(lone) pairs are not represented in structural diagrams.

Question 15

Covalent Bonding-Molecular Substances

What are the steps for drawing Lewis Structures and Structural Diagrams of Molecular compounds?

Answer 15

1. Draw a lewis structures diagram of the atom that has the highest bonding capacity.
2. Form shared pairs of bonding electrons with the remaining atoms.
3. If any bonding electrons remain on adjacent atoms, form a double or triple bond.
4. In the finished electron dot diagram, all atoms(except hydrogen) should contain a stable octet, counting lone pairs plus shared electrons.
5. Draw the structural diagrams for the molecule(just show the bonds, no lone pairs).

Question 16

Metallic Bonding

What is metallic bonding?

Answer 16

Metals are held together within their structure with metallic bonding which is caused by the simultaneous attraction of two or more nuclei for the same electrons.
In metallic bonding the valence electrons are shared b all atoms, the electrons almost form a sea or cloud around the nuclei or are said to be delocalized.

Question 17

Metallic Bonding

Why is a Metallic Bonding Model good?

Answer 17

1. The presence of free mobile electrons in the metallic structure is consistent with the electrical conductivity of most metals.
2. The relatively strong electrostatic attraction between stationary positive ions and valence electrons explains why all metals except mercury are solids under ordinary conditions, and most have relatively high melting points.
3. The valence electrons in the metallic structure are not localized and thus the metallic bounding is not directional. This non-directional nature of metallic bonds permits the kind of slippage effect between positive ions thereby accounting for the malleability and ductility of metals.

Question 18

What is an Element?

Answer 18

Pure substances, the same type of atom.

Question 19

What are the properties of metals?

Answer 19

• Has lustre
• Are good conductors of electricity and heat.
• Malleable
• Ductile
• Solid at room temperature.

Question 20

What are the properties of non-metals?

Answer 20

• No lustre
• Bad conductors
• Brittle
• Solid, liquid and gas at room temperature.

Question 21

What are the properties of metalloids?

Answer 21

-Can conduct when heated.

Question 22

How do you prove that something is an element?

Answer 22

• Heat it to find out if it will separate.

- Electrify it.

Question 23

How do you prove a compound?

Answer 23

Heat it, if it separates it’s a compound.

Question 24

Properties that create an element.

Answer 24

The number of protons.
The number of electrons.
Geometry or spacing.

Question 25

What evidence is there that the electron structure of noble gases is stable?

Answer 25

Noble gases are stable because they are formed with eight electrons in their valence shell and rarely react.

Question 26

Define and give an example of bonding electrons.

Answer 26

Bonding electrons are the electrons that are not paired in a single atom.

Question 27

Define and give an example of bonding electrons.

Answer 27

Bonding electrons are the electrons that are not paired in a single atom.

Question 28

Define and give an example of a lone pair.

Answer 28

Lone pair is a pair of electrons that exist in a single atom.

Question 29

Give a definition of an ionic bond. Then, state a generalization of which groups of elements in the periodic table form ionic bonds.

Answer 29

Ionic bonds are a compound where electrons are transferred between atoms to form stable octets. Ionic bonds are formed by a metal and a non-metal.

Question 30

i) State the group number of each atom.
ii) State whether it must gain or lose electrons to achieve the electron structure of the nearest noble gas and how many electrons are involved.
iii) Name and write the formula of the resulting ion after the electron(s) loss or gain.
a) Na
b) Mg
c) S
d) Cl

Answer 30

Na-1, Loss, sodium ion, [Na]+1
Mg-2,Loss, magnesium ion, [Mg]+2
S-16,Gain, sulfur ion, [S]-2
Cl-17, Gain, chloride ion, [Cl]-1

Question 31

For the element carbon:

a) State is group number.
b) State whether it must gain or lose electrons to achieve the nearest noble gas and how many electrons are involved.
c) Considering your answer in part be, is there an alternative way for carbon atoms to gain a noble gas-like structure or configuration? Explain.

Answer 31

14, Carbon needs to gain 4 electrons, It could form a molecular compound and share its electrons.

Question 32

Give a definition of a covalent bond. State a generalization of which group of elements in the periodic table will likely form a covalent bond.

Answer 32

A covalent bond is where electrons are shared between atoms to form stable octets. It occurs when a non-metal reacts with a non-metal.

Question 33

Give a definition of a metallic bond. State a generalization of which groups of elements in the periodic table will likely form metallic bonds.

Answer 33

Metallic bonds are a collection of atoms that delocalized their electrons to form a conductive, malleable and ductile solid. Only metals form metallic bonds.

Question 34

Based on the positions of the elements in the periodic table, predict whether the bonding between atoms in the following substances would be ionic, covalent or metallic.

• KCl(s)
• Mg(s)
• CaO(s)
• O2(g)
• NO2(g)
• Ag(s)
• BaCl2(s)
• S8(S)
• SO2(g)
• CsF(s)

Answer 34

• KCl(s)Ionic
• Mg(s)Metallic
• CaO(s)Ionic
• O2(g)Covalent
• NO2(g)Covalent
• Ag(s)Metallic
• BaCl2(s)Ionic
• S8(S)Covalent
• SO2(g)Covalent
• CsF(s)Ionic